Dresser Roots Gas Meter – Ultimate Guide
Everything You Need to Know About Dresser Utility Solutions Roots Gas Meters
This ultimate guide explains how Roots positive displacement rotary gas meters work, where they’re used, how to size and read them, and how to compare models, outputs, and accessories. You’ll also learn installation best practices, startup procedures, maintenance and light repair tips, what’s coming next in digital metering, and where to buy Roots Meters & Accessories.
Who This Guide Is For
This guide is written for professionals responsible for gas metering systems, including:
- Utility technicians and field crews
- Facility, mechanical, and process engineers
- Mechanical contractors and estimators
- Metering skid fabricators and system integrators
- OEM equipment builders
- Industrial buyers and procurement teams
- Wholesalers and distribution partners
Whether you’re quoting a project, replacing a legacy meter, integrating meters into packaged skids, or evaluating options for a new installation, this guide gives you the technical clarity needed to move forward with confidence.
Looking for Howden ROOTS blowers or compressors? This guide covers Dresser ROOTS rotary gas meters, not blower or compressor products. We also don’t sell couplings or fittings. See our clarification below.
Roots Meter IOM Manual PDF Download
SCAN QR CODE
Official Dresser Roots B3 Series Manuals & Guides
SHOP ONLINE NOW!
Table of Contents
- What Is a Gas Meter?
- How to Size a Roots Gas Meter
- Meter Size Comparison
- Model Breakdown
- Versions Explained
- Output Options
- High Pressure Gas Meters
- Resources
- FAQ
- How Do I Size a Gas Meter?
- What is the best flow meter for natural gas?
- What’s the Difference Between ACFH and SCFH?
- Can a Roots Meter Be Used for Propane?
- Can a Roots Meter Measure Liquid?
- How Often Should a Gas Meter Be Calibrated?
- What If a Roots Meter Is Installed for Reverse Flow?
- Do You Sell Howden ROOTS Blowers or Compressors?
- Who Manufactures Roots Gas Meters?
- New Product Highlight: MC3 Guardian (2026)
What Is a Roots Gas Meter?
A Roots gas meter measures how much gas moves through a pipeline or system over time. One of the most trusted types in commercial and industrial applications is the positive displacement rotary roots gas meter. In residential settings, gas meters track how much natural gas a home uses for billing. In commercial and industrial contexts, gas meters perform the critical role of measuring fuel gas (like natural gas, methane, propane, etc.) consumption or flow for larger facilities, utility custody transfer, and process control.
How Does a Roots Meter Work?
Understanding Rotary Gas Meters
Similar to a turnstile at a train station counting one person at a time as they walk through. A rotary gas meter works the same way. Inside the meter, two figure-eight-shaped impellers rotate in opposite directions, allowing 1 cubic foot of gas through. Because it tracks actual gas volume, it stays accurate even when flow rates change. This makes rotary meters made by Dresser Utility Solutions a top choice for gas utilities, contractors, and commercial buildings across the U.S.
Unlike other meter types—such as turbine, orifice, ultrasonic, or thermal mass meters—that estimate flow based on speed or pressure changes, a rotary gas meter measures real volume directly. An industry standard for over a century.
What Makes Them Unique?
Wide Rangeability (High Turndown Ratio)
A key advantage of Roots meters is their ability to accurately measure gas flow across a very wide operating range. They can perform reliably at both extremely low and very high flow rates without sacrificing accuracy.
97% Accuracy at only 3% of flow
Low Pressure Drop
Because of their rotary positive displacement design, Roots meters create very little resistance to flow. The low-friction internal mechanism results in minimal differential pressure across the meter, even at high flow rates.
Roughly 0.1 – 2.5 Inches W.C. ~ Based On Meter Size
Consequently, Dresser Roots meters perform exceptionally well in low-pressure systems, vapor recovery applications, and installations where maintaining line pressure is critical to downstream equipment.
No Straight Pipe Run Required
Rotary meters don’t rely on flow conditioning (unlike turbine or ultrasonic meters) to maintain accuracy. As a result, Dresser Roots meters don’t require long straight pipe runs upstream or downstream. This flexibility simplifies installation, especially where space is limited.
Field-Changeable Accessories
Dresser Roots meters use a magnetic drive between the measuring chamber and the external index or accessory. This sealed design reduces leak risk and allows technicians to change registers or “heads”, add pulse outputs, or upgrade to electronic volume correctors in the field.
Rugged, Long-Lasting Construction
Dresser Roots meters are engineered for long service life in demanding environments. Critical components—including the impellers, housing, bearings, and timing gears—are manufactured to tight tolerances using durable materials.
Because of this robust construction, many Roots meters remain in service for decades with minimal maintenance. In addition, they operate reliably across a wide temperature range (typically from -40°F to +140°F) and are well suited for outdoor installation.
Applications
Natural Gas Utilities (Distribution & Service)
Gas distribution companies widely use Dresser Roots meters at industrial, commercial, and large residential customer sites for billing and system monitoring. For example, utilities commonly install Roots meters at factories, apartment buildings, and institutional facilities to measure delivered gas volume accurately.
In addition, these meters are used throughout the distribution network—from city gate stations, where gas enters local systems, to district regulator stations and large end users. Because of their proven meter consistency under variable conditions, long-term stability, and reliability, Dresser Roots meters remain the preferred rotary positive displacement meter for utility distribution systems.
Industrial and Commercial Facilities
Industrial and commercial facilities such as factories, hospitals, universities, and large campuses often rely on Dresser Roots meters to measure incoming natural gas used for boilers, furnaces, ovens, or combined heat and power (CHP) systems. These applications demand meters capable of handling high and highly variable flow rates.
Furthermore, many industrial plants use Roots meters internally for sub-metering individual processes or departments. Their wide turndown ratio makes them especially useful in environments where gas demand fluctuates significantly between peak production and off-hours.
Upstream Oil & Gas (Production and Gathering)
In upstream production and gathering applications, high-pressure Dresser Roots meters (HPC models) measure gas directly at wellheads, gathering systems, and compressor stations.
For instance, a 1M1480 meter may be installed at a high-pressure well site with relatively modest flow rates. The rugged construction allows the meter to perform reliably in outdoor and remote environments, while its sensitivity to low flow helps detect leaks or declining production.
Agricultural and Specialty Applications
Dresser Roots meters are also used in agricultural and specialty applications, including grain dryers, irrigation pumps, and greenhouse heating systems that operate on natural gas or propane.
For example, models such as the 2M175 or 5M175 are commonly installed to monitor fuel usage during crop drying or greenhouse heating cycles.
Biogas and Wastewater Treatment Facilities
Biogas-producing facilities, including landfill gas systems and anaerobic digesters at wastewater treatment plants, frequently use Dresser Roots meters to measure biogas flow.
To support these harsh environments, Dresser offers Special Service Meter (SSM) variants designed for moist, corrosive gases such as digester gas. These meters help operators track gas production for cogeneration, energy recovery, or flaring, while maintaining low pressure drop—an important consideration in low-pressure biogas systems.
Custody Transfer and Billing Applications
Whenever natural gas is bought, sold, or transferred between parties, accurate custody transfer measurement is essential. Dresser Roots meters appear at custody transfer points throughout the gas value chain—from “the well to the burner.”[reference]
Their widespread use in billing applications stems from their long-term accuracy, mechanical stability, and ease of proving and calibration to meet regulatory and contractual requirements.
How to Read a Dresser Roots Gas Meter
Standard B3 Series meters (such as the CTR or TC) use a black mechanical odometer-style register index to show the total volume of gas that has passed through in cubic feet.
What You’re Looking At
Dresser Roots gas meters (8C through 11M) show five digits on the display. Larger meters (16M through 56M) show six digits. These digits represent the total volume of gas the meter has measured—just like the mileage counter on a car. This is not to be confused with a speedometer, which would be tied to a real-time flow rate.
- Left-most digit: Often hidden behind a black mask (an industry standard).
- Center-most digits: These are the white numbers you care about, between the arrows.
- Right-most digits: Covered by a translucent blue mask window. These are less than 100 feet used for precision measurement testing, not for normal reading. These are the “tens” and “ones” digits.
Understanding the Multiplier
Standard Mechanical Odometers include a multiplier on the aluminum faceplate, such as “Reading ×100 = Cubic Feet”. That means if the display reads 02576, you multiply that by 100 to get 257,600 actual cubic feet (ACF).
Temperature-Compensated Meters (TC Models)
If you’re reading a temperature-compensated (TC) meter, you’ll typically see two odometers:
- The top display shows the corrected volume (adjusted to 60°F standard conditions or “SCF”).
- The bottom display shows the uncorrected volume (actual volume at line conditions or “ACF”).
This feature is useful for outdoor installations where temperature affects gas density. The corrected reading gives a more accurate measurement of energy usage over time.
Digital Indexes and Correctors
More advanced meters may include a Micro Corrector. This battery powered LCD display will show corrected volume by default, with other parameters to scroll through. Additionally, 3rd Party Correctors are also offered. Those units are often mounted to CD (Counter/Drive) or TD (Temperature/Drive) versions.
SUMMARY
Always read the digits between the arrows —ignore masked areas.
Use the multiplier indicated on the meter faceplate to get the total volume. Typically x100.
How to Size a Roots Gas Meter
Some people assume a gas meter should match the pipe size—but that’s not the case. The meter size should match the flow, not the pipe. Once you’ve selected the correct meter based on flow rate and pressure, you can always adapt the piping to fit the meter connections.
What You Need:
- Flow Rate – Usually measured in Maximum Cubic Feet or alternatively Maximum BTU
- Line Pressure – PSIG or inches of water column
- Line Size – This is used for sizing the installation mating flanges, not the gas meter
- Outputs – Do you need to read your meter remotely from a different location?
- Totalization – totalized volume measurement for billing and accounting.
Rate – for real-time flow rate measurement and process monitoring.
These can then be tied into your PLC or Management System. Roots does not currently offer 4-20mA or Digital Communication such as Ethernet or Wireless.
- Totalization – totalized volume measurement for billing and accounting.
If your line pressure is less than 1 PSI (27.7 inch w.c.), pressure correction is not critical
Aim for a meter that operates in the middle of its rated range for best results. You wouldn’t drive your car 100 MPH everywhere you go, and your gas meter shouldn’t either. With that said, do people use a 3M175 for 3,000 CF Max? Yes, they do.
Tip: You can size up to the next larger meter for future expansion or additional gas loads.
Sizing for BTU
1 CF ≈ 1,000 BTU/hr
1 MBH ≈ 1,000 BTU/hr
EXAMPLE: 800,000 BTU/hr of natural gas. Natural gas contains about 1,000 BTU per cubic foot, that equals 800 ACFH. You could use an 8C175 Roots meter, which is rated for 800 ACFH at standard conditions. This works well for low-pressure systems (under 2 PSI or Inches W.C.).
| CFH (Natural Gas) | BTU/hr Equivalent |
| 62.5 CFH | 62,500 BTU/hr |
| 125 CFH | 125,000 BTU/hr |
| 250 CFH | 250,000 BTU/hr |
| 500 CFH | 500,000 BTU/hr (½ MBTU) |
| 1,000 CFH | 1,000,000 BTU/hr (1 MBTU) |
| 5,000 CFH | 5 Million BTU/hr |
| 10,000 CFH | 10 Million BTU/hr |
| 20,000 CFH | 20 Million BTU/hr |
Sizing for Propane
1 CFH ≈ 2.5 MBH Propane
Propane has a higher energy content than natural gas—about 2,517 BTU per cubic foot. To size your meter correctly for propane:
Multiply your propane BTU/hr by 2.5 to find the equivalent ACFH load needed.
Example Conversions:
- 15C175 (1,500 ACFH × 2.5) = 3,750 CFH = 3.75 MBTU/hr propane
- 5M175 (5,000 ACFH × 2.5) = 12,500 CFH = 12.5 MBTU/hr propane
- 7M175 (7,000 ACFH × 2.5) = 17,500 CFH = 17.5 MBTU/hr propane
- 11M175 (11,000 ACFH × 2.5) = 27,500 CFH = 27.5 MBTU/hr propane
Pressure Correction (Why It Matters)
Gas expands and contracts based on pressure and temperature. At higher pressures, gas takes up less space by compression. If your gas meter doesn’t correct for that, your readings may be very misleading.
If your gas line runs at 5 PSIG, your gas is about 1/3 more dense than it would be at atmospheric pressure. That means your gas meter will see more actual gas passing through (unknown by the meter), even though the volume looks the same. Without correcting for this, your readings would be off by a third. At 30 PSI, your readings would be off by 3x.
To account for this, industrial gas flow measurement with volume correction (like the IMCW2 Micro Corrector) is crucial for maintaining accuracy.
This allows the system to convert readings Actual Cubic Feet (ACF) into Standard Cubic Feet (SCF)—a universal standard used for billing and comparisons.
Internal vs. External Volume Correction
You have two main options:
- Internal Correction – Some meters come with built-in mechanical temperature correction (TC models), or with electronic units like the IMC/W2 that automatically adjust for pressure and temperature internally in the meter body.
- External Correction – You can also tap the gas line with a pressure sensor and thermocouple, then use either use a Micro Corrector (IMCW2) or a 3rd party volume corrector to adjust the readings.
GAS PRESSURE & TEMPERATURE CORRECTION FACTORS PDF
(See Page 5)
Why A Strainer Is Important
Dresser Roots rotary gas meters are built for exceptional meter consistency under variable conditions — but like any precision instrument, they require protection from contamination in the gas line, even brand-new pipes. The internal figure-eight impellers inside every meter are precisely machined and perfectly timed, with clearances as tight as a human hair. This ultra-fine tolerance ensures accurate measurement of every cubic foot of gas—but it also makes the meter vulnerable to damage from particles.
In real-world installations, gas piping often contains pipe scale, rust flakes, dirt, weld slag, or other debris like PTFE Tape strings or Pipe dope. These can come from new construction, aging pipes, or routine line work. If this material enters the meter:
What Can Go Wrong?
- It can scratch or jam the impellers
- Disrupt the meter’s timing gears and jam or lock-up
- Cause long-term wear or immediate failure
- Require expensive repairs or replacement ( 2/3 the price of a new meter)
Dresser’s Recommendation
To protect your investment and ensure long-term meter performance, Dresser Utility Solutions strongly recommends installing a strainer upstream of every Roots gas meter.
“Y” Strainer:
- Installed in-line with the piping
- A removable blow off plug cap for easy cleaning (outdoor applications)
- Easier to service and ideal for systems where maintenance access is available with bypass
Gasket Strainer:
- Inexpensive
- Sits directly between the meter flange and companion flange (inlet side)
- Very compact and easy to install during meter assembly
- Less serviceable than a “Y” strainer, but a great choice for tight spaces or short-term setups
Whether you’re installing a new meter or replacing an old one, including a strainer gasket is one of the simplest and most effective ways to extend the life of your gas metering system
SUMMARY
Yes, installing a strainer (or filter) on the inlet side of a gas meter is highly recommended, and in many cases necessary, to protect it from damage caused by debris, pipe scale, welding slag, and foreign material
Size Comparison
Choosing the right Roots meter model depends on the flow rate and pressure of your application. Below is a comparison of Dresser Roots gas meter models by their size (capacity), pressure rating, and connection. This guide can help you identify which model might fit your needs. (All flows are given at Actual Cubic Feet per Hour (ACFH), and pressure ratings are the standard MAOP for that model.)
| Model | Flow Capacity (Max ACF) | Max Pressure (PSIG) | Typical Connection |
| 8C175 | 800 ACF | 175 psi | 2″ ANSI 125/150 FF flange |
| 11C175 | 1,100 ACF | 175 psi | 2″ ANSI 125/150 FF flange |
| 15C175 | 1,500 ACF | 175 psi | 2″ ANSI 125/150 FF flange |
| 2M175 | 2,000 ACF | 175 psi | 2″ ANSI 125/150 FF flange |
| 3M175 | 3,000 ACF | 175 psi | 2″ ANSI 125/150 FF flange |
| 5M175 | 5,000 ACF | 175 psi | 3″ ANSI 125/150 FF flange |
| 7M175 | 7,000 ACF | 175 psi | 3″ ANSI 125/150 FF flange |
| 11M175 | 11,000 ACF | 175 psi | 3″ ANSI 125/150 FF flange |
| 16M175 | 16,000 ACF | 175 psi | 4″ ANSI 125/150 FF flange |
| 23M232 | 23,000 ACF | 232 psi | 4″ ANSI 125/150 FF flange |
| 23M175 | 23,000 ACF | 175 psi | 6″ ANSI 125/150 FF flange |
| 38M175 | 38,000 ACF | 175 psi | 6″ ANSI 125/150 FF flange |
| 56M175 | 56,000 ACF | 175 psi | 8″ ANSI 125/150 FF flange |
| 102M125 | 102,000 ACF | 125 psi | 10″ ANSI 125/150 flange |
Model Numbers (How They Work)
- C Models “C” is Roman numeral for 100. (8C175, 11C175, 15C175) are smaller capacity meters (800, 1100, 1500 ACFH Max Base Rating).
- M Models “M” is Roman numeral for 1000. 2M175 – 102M indicate thousands of cubic feet per hour (example: 5M = 5,000 ACFH Base Rating).
- 175 = 175 MAX PSIG rating
Model Breakdown
Beyond the standard lineup, Dresser offers a wide range of specialty gas meter configurations to support advanced measurement, automation, communication, and challenging environments. These options are tailored for everything from basic pulse output to full digital diagnostics and remote monitoring.
📄B3 SERIES METER BROCHURE
📄DRESSER METER FACT SHEET
Here’s a breakdown of the most common Dresser variants, organized for clarity:
Mechanical & Utility-Focused
| MODEL | MEANING | DESCRIPTION |
|---|---|---|
| CTR | Counter (Standard Mechanical) | Standard base model with mechanical index, no compensation or outputs. Requires no power. |
| TC | Temperature Compensated | Temperature Corrected Volume Mechanical Index, with Non-Compensated Volume index as well. Requires no power. No Outputs. |
| CD | Counter Drive | Mechanical Counter with Universal Mounting Plate & Drive Dog Output for external recording or mechanical remote reading. Digital Communication Capabilities via 3rd Party Units. |
| TD | Temperature Drive | Same as above. Add temperature correction. |
| SSM | Special Service Meter | Built for sour gas, biogas, and corrosive gas environments. Enhanced materials. Requires no power. Available as an adder on common meters, standard on high pressure. |
| VRM | Vapor Recovery Meter | Used in vapor recovery systems with minimal backpressure. Extremely low pressure drop. Requires no power. |
| LMMA | Line Mount Meter (A Series) | OBSOLETE. It was a small lightweight & versatile meter with no outputs. Replaced by Standard B3 Series CTR Model with 1/2″ Pipe Nipple Connections. |
| HPC | High Pressure Cartridge | Ideal for High Pressure application 300/740/1480 PSI. For ANSI 300/600. Restricting orifice plate included. |
| HPC-BPV | High Pressure Cartridge Bypass Valve | Same as above, includes Bypass Valve to protect overspinning impellers and maintenance without downtime. |
Mechanical Accessories
| MODEL | MEANING | DESCRIPTION |
|---|---|---|
| ICPWS/ICPWD | Integral Counter Pulser Wiegand Single / Double | Mechanical Counter with Solid State Pulse Output (1 per 10CF – 8C-11M, 1 Pulse per 100CF – 16M+) Form C (3-30 VDC Required). “D” version includes two outputs. |
| ITPWS/ITPWD | Integral Temperature Pulser Wiegand Single / Double | Mechanical Counter with One Temperature Compensated Pulse Output (1 per 10CF – 8C-11M, 1 Pulse per 100CF – 16M+) Form C (3-30 VDC Required). “D” version includes two outputs. |
| ICEX | Integral Counter Electronic Transmitter | Mechanical Counter with High Speed Electronic Pulse Output. Used for Remote Reading of Flow Rate. (3-30 VDC Required). |
Volume Correctors
| MODEL | MEANING | DESCRIPTION |
| IMC-T | Integral Micro Corrector (Temperature Correction only) | Corrects for temperature. Basic volume correction for outdoor or unregulated installs. |
| IMC-P | Integral Micro Corrector (Pressure Correction only) | Corrects for pressure. Used in pressurized systems where pressure variation affects volume. |
| IMCW2-PTZ | Integral Micro Corrector + Wiegand v2, Pressure, Temperature, Datalogging | Pressure & Temperature Volume Correction w/ Datalogging |
| IMC-PTZ-DP | Same as above + Differential Pressure Monitoring | Same as above + Differential Pressure Monitoring for meter health (not accuracy) |
| MC3 Guardian | Micro Corrector v3 | Volume correction + real-time monitoring, alerts, remote diagnostics, digital communication |
Electronic Accessories
| MODEL | MEANING | DESCRIPTION |
|---|---|---|
| ETC | Electronic Temperature Compensator | Digital replacement for mechanical TC—used where an electronic display is preferred. AMR Compatible. Datalogging (150 Days). 2-min prover testing. Fixed Factory Pressure Compensation |
| ES3 | Electronic Security | Electronic compensation with the security of a proven mechanical index. AMR Compatible. Fixed Factor Pressure Compensation. |
| AMR | Automated Meter Reading | AMR-compatible output for remote gas meter reading via radio or digital signal (e.g.: ITRON, Sensus etc). Require the adaptation of a Residential ERT or Cellnet AMR. |
Residential Low Flow
| MODEL | MEANING | DESCRIPTION |
|---|---|---|
| D600/D800/D1000 | Diaphragm | Residential Diaphragm Meters for Commercial Use |
| 10C25-DI (Series K) | 1000 ACFH / 25 PSI Rated Digital Instrument Index | Converts mechanical data to electronic format—AMR Capable. Small size, ideal for meter banks. Fast Testing via SNAP Prover. Fixed Factor Pressure Compensation |
| 10C25-T / V | 1000 ACFH / 25 PSI Rated Digital Instrument Index | Same as above, “T” temperature compensated version, “V” Vault version for IP68 submersion. |
Versions Explained
CTR (Counter)
5-Digit Non-Compensated Mechanical Odometer that reads in Actual Cubic Feet (ACF) or in Actual Cubic Meters (m3) outside of the USA. No Outputs. Requires no power. Used in Monthly Total applications.
SSM (Special Service Meter)
Same as above. All carbon steel parts have been eliminated from the gas stream. The bearings, timing gears, spring clips, and internal cap screws are made of stainless steel. The bearing retainers and timing gear clamps are made of anodized aluminum. All aluminum parts of the measurement chamber are hard coat anodized for added corrosion and abrasion resistance. Used in Monthly Total applications with Wet/Corrisive gases (such as production pipeline or sludge digester).
TC (Temperature Counter)
Includes TWO 5-Digit Mechanical Odometers for Temperature Corrected Volume (Base temperature of 60°F/15°C) & Non-Compensated Volume (Uncorrected). No Outputs. Requires no power. Used in Monthly Total Billing applications with Temperature Correction.
Solid State Pulsers
ICPWS/ICPWD (Integral Counter Pulse Wiegand Single / Double) – 5-Digit Non-Compensated Mechanical Odometer with a Solid State Pulser. Generates low frequency pulses (Form C, Form A acceptable). 3-30 VDC Loop Voltage required across Brown (+) and Green (-) wires. “D” version includes two outputs. Used in Monthly Total Billing applications with Remote Reading capability.
ITPWS/ICPWD – (Integral Temperature Pulser Wiegand Single / Double) – Same as above, but Temperature Compensated. “D” version includes two outputs. Used in Monthly Total Billing applications with Remote Reading capability with Temperature Correction.
NOTE: These versions cannot be converted into 4-20mA analog signal. They are for TOTAL, not flow RATE.
High-Speed Electronic Transmitter
ICEX (Integral Counter Electronic Transmitter) – 5 Digit Non-Compensated Mechanical Odometer with High-Speed Frequency Electronic Pulse Output (Form C, Form A acceptable). 3-30 VDC Loop Voltage required across White (+) and Black (-) wires. Used in FLOW RATE & Total applications (like the speedometer in your car) with Remote Reading capability. Can be converted into 4-20mA analog signal.
Instrument Drive
CD (Counter Drive)– 5 Digit Non-Compensated Mechanical Odometer with Instrument Drive. Includes a Universal Mounting Plate for installations of 3rd Party locally mounted and mechanically driven devices (Volume Correctors like the Honeywell EC350) via a plastic “drive dog” pin. Requires no power at the meter itself. Used in Monthly Total Billing Applications with Added Features like Volume Correction & Digital Communication (Modbus, Ethernet etc.)
TD (Temperature Drive) – Same as above with Internal Temperature Compensation. Includes TWO 5-Digit Mechanical Odometers for viewing Temperature Corrected Volume & Non-Compensated Volume (Uncorrected). No Outputs. Requires no power. Used in Monthly Total applications with Temperature Correction with Added Features like Volume Correction & Digital Communication
Volume Corrector
The Flagship Model
IMCW2-PTZ (Integral Micro Corrector Wiegand v2, Pressure, Temperature, Datalogging)
The flagship model of Dresser Roots Gas meters. Offers internal (typically 8C-16M) or external pressure & temperature volume correction. Features a rotatable Lithium Battery Powered LCD display for viewing corrected or uncorrected flow, plus additional parameters.
IMCW2-DP (Integral Micro Corrector Wiegand v2, Pressure, Temperature, Datalogging, + DP Measurement)
Same as above, includes Differential Pressure measurement snapshots in 30 second intervals to monitor and log the health of the meter (not accuracy).
Optional MCUT User Terminal Software allows connection to a Windows PC to change settings, view alarms/faults, and datalogging with excel. The optional Solid State Pulse Output generates low frequency pulses (Form C, Form A acceptable). 5-15 VDC Loop Voltage required across White (+) and Black (-) wires. Used in Monthly Total Billing Applications with Pressure & Temperature Volume Correction, Datalogging Features, and optional Remote Pulse Output capability.
HPC (High Pressure Cartridge)
Offers a wide range of flow and pressure. Ranges include 232, 300, 740, and 1480 PSIG Max. Applications include production wellhead, gathering applications, gas transmission, farm taps, grain dryers, irrigation and compressed fuel taps. Requires no power. Used in Monthly Total applications with High Pressure.
BPV (Bypass Valve) – Same as above. The optional BPV (Bypass Valve) is a robust design with self-resealing edges. It is always closed unless the differential pressure exceeds the spring rate and lets the gas flow through the bypass, whether in a short burst or full flow – if the meter locks up. The valve opens due to high differential and allows gas to flow around the measuring chamber to keep the customer on line with gas supply.
VRM (Vapor Recovery Meter) – 5 Digit Non-Compensated Mechanical Odometer Rated for 800 ACFH or 3000 ACFH. This meter is designed and tested for vapor recovery applications. Odometers are marked at 0.2 CF increments, which allows accurately estimated readings in increments of 0.1 cubic feet (± 2 percent). The extremely low pressure drop of PD rotary meters (0.64 Inches W.C.) make this meter ideal for accurate measurement of low pressure recovery systems. Ships with a 7-point certified accuracy test curve. Requires no power. Used in Volumetric Flow Rate applications.
ETC (Electronic Temperature Compensator) – Tamper-resistant (magnetic scrolling) 5-Digit LCD Display. Easily connects via a single cable for 2 Minute proving time with the Model 5 and Model 6 Provers. Compatible with Dresser MeterWare. Features Temperature Correction and Fixed-Factor Pressure Correction. Includes available adapters for retrofitting to LMMA A-Series meters, or AMR devices / Remote ERT (like Itron). Circular Pulse Output with Form A & Form B (AMR version only). Used in Custody Transfer applications.
ES3 – Electronic compensation with the security of a proven mechanical index. AMR Compatible. Fixed Factor Pressure Compensation. Used in Custody Transfer applications.
AMR (Automatic Meter Reading) – Dresser Utility Solution’s residential AMR Adapter for the Series 3 CTR/TC index units allows you to mount an Itron® Residential ERT® 40G for Invensys or American Meters directly onto a Dresser Series B3 Rotary Meter. Additionally, the Adapter facilitates the mounting of a Cellnet Module directly to the end of a Dresser Rotary Meter.
RA100 XMTR –An Instrument Drive mountable High Frequency Pulse Output Transmitter. 10-15 VDC Power Required. Works with meters sizes 1.5M up to 102M.
S3A (Series 3 Accessory) – With the S3A, a retrofit for older style LMMA meters with modern accessories like B3 Series CTR, TC, TD, ICEX, ICPW/ITPW, CTR/AMR Adapter available for Itron & Sensus
LMMA (Line Mounted Meter A Series) – OBSOLETED (1998) – The 8C175LMMA was a compact meter, like the Series Z, was designed for small commercial applications, but with a higher pressure rating. Built with 1-1/2” Pipe Nipple Connections. It was also available as a vapor recovery meter.
Residential Meters
D630 – Residential Diaphragm Meter (630 ACFH) – Designed for long-term accuracy and low-pressure natural gas and LPG service. Compact residential meter designed for light-to-medium gas loads. Offers reliable measurement for homes and small commercial spaces. Available in standard non-compensated or temperature-compensated (TC) versions.
D800 – Residential/Light Commercial Diaphragm Meter – Slightly larger-capacity residential meter for higher appliances or small businesses. Provides stable accuracy, with TC options for improved billing precision in changing temperatures.
D1000 – High-Capacity Residential/Commercial Diaphragm Meter – Higher-flow diaphragm meter suited for large homes, mixed-use buildings, and small commercial loads. Available in standard or TC versions, with durable long-life components and easy installation.
10C25 – Similar to the D1000 and rated for 1000 ACFH, it holds advanced features in a small package. Sized for applications typically reserved for large diaphragm meters, the 10C25 DI (Digital Instrument) allows for ease of installation and aesthetics while also providing measurement capabilities typically reserved for larger sized rotary meters. Versions include non-compensated (DC) or Temperature Compensated (DI-T). Used in tight-space meter banks commonly used in multi-tenant buildings like apartment complexes, condominiums, and office buildings. Also available for Curb/Vault (IP68).
Output Options
Connections Types
Available Electrical Connection Styles
Dresser Roots accessories and pulse-output devices are available with several electrical connection options to match different installation environments and wiring preferences. Because the right connection style protects signal wiring, simplifies installation, and improves long-term reliability, it plays a critical role in outdoor and industrial applications.
MS-Style Circular Connector “CIR” (shown left)
This rugged, multi-pin circular connector allows quick connection and disconnection of field cables. As a result, technicians can service or replace accessories without re-pulling conduit. The mating cable is sold separately and is available in multiple lengths.
Cable Gland with 4-Foot Pigtail “CBG” (shown middle)
This configuration includes a sealed 3/8″ cable gland and a factory-installed 4-foot lead wire. Therefore, it is commonly selected for fast field termination into junction boxes, control panels, PLC inputs, or remote totalizers while maintaining strain relief and moisture protection. Additionally, ideal for modular installs and quick disconnect setups.
1/2-Inch Liquid-Tight Conduit Connector “CND” (shown right)
Designed for permanent conduit installations, this option lets electricians run rigid or flexible conduit directly into the accessory housing. Consequently, it delivers excellent mechanical protection and environmental sealing in harsh industrial or outdoor locations.
All three connection styles are commonly offered with cable lengths of 4 feet, but also available in 10 feet, or 25 feet to match site requirements.
Outputs
Dresser Roots gas meters can be equipped with two pulse output options, allowing them to interface with remote displays, PLCs, SCADA systems, flow computers, and building automation controls like EMS. There are two main types of pulse outputs commonly used, each with distinct functions:
1. SOLID-STATE PULSE OUTPUT (ICPWS)
This is the most widely used output for totalization and remote reading. It provides an analog solid state dry-contact, Form C (Form A Acceptable), DC square-wave signal, typically used for utility billing, monthly volume tracking, or remote monitoring applications. 3-30 VDC Required (5-15 VDC for IMCW2 Models)
- Wiring: 2-wire, 24 AWG
- Brown + (N/O)
- Green – (Common)
- Red = Fault (N/C)
- (For IMCW2 Model: White +, Black -)
- 3-30 VDC Required
- 10 mA MAX Supply Current
- (5-15 VDC on IMCW2 Model)
- Typical Output Rate:
- 1 pulse per 10 cubic feet for 8C through 11M
- 1 pulse per 100 cubic feet for 16M and larger
- Common Uses:
- Remote digital displays
- Utility monitoring systems
- Building management systems (BMS)
- SCADA inputs for cumulative gas usage
2. HIGH-SPEED ELECTRONIC PULSE OUTPUT (ICEX)
This output generates high-frequency electronic pulses tied directly to impeller rotation, allowing precise real-time flow rate measurement. Similar to a water meter outputting GPM or your car’s speedometer (not the odometer), it shows how fast gas is moving at that moment. However, you can still totalize those pulses for monthly billing or reporting.
- Wiring: 2-wire, 24 AWG
- White + (N/O)
- Black – (Common)
- Red = Fault (N/C)
- 3-30 VDC Required
- 10 mA MAX Supply Current
Use Case: Real-time flow measurement, batching, control room monitoring
Output Type: High Frequency Electronic Pulse (3-30 VDC), often converted to 4–20 mA analog output using external converters
📄 View ICEX Datasheet
📄 View ICEX Install Manual
ICEX Pulse Output by Meter Size
| Meter Model | Pulse Volume (CF) | Pulses per 1 CF |
| 8C175 | 0.00185 CF | 540 |
| 11C175 | 0.00208 CF | 480 |
| 15C175 | 0.00250 CF | 400 |
| 2M175 | 0.00500 CF | 200 |
| 3M175 | 0.00625 CF | 160 |
| 5M175 | 0.00926 CF | 108 |
| 7M175 | 0.01563 CF | 64 |
| 11M175 | 0.02500 CF | 40 |
| 16M175 | 0.03704 CF | 27 |
| 23M232 | 0.05000 CF | 20 |
| 38M175 | 0.13889 CF | 7 |
| 56M175 | 0.17361 CF | 6 |
High-Pressure Roots Gas Meter
HP / HPC – High Pressure Cartridge
These models use heavy-duty housings and pressure-rated internals to handle gas systems operating at 300 PSIG, 740 PSIG, or even up to 1480 PSIG. In other words, they maintain the same positive displacement measurement principle but are engineered for higher stress environments.
| Model | Based Rating (ACFH) | Pressure Rating (PSIG) | Connection Size |
|---|---|---|---|
| 1M300 | 1,000 | 300 | 1-1/2″ FF FLG ANSI 300 |
| 3M300 | 3,000 | 300 | 2″ FF FLG ANSI 300 |
| 1M740 | 1,000 | 740 | 2″ RF FLG ANSI 300 |
| 3M740 | 3,000 | 740 | 2″ RF FLG ANSI 300 |
| 1M1480 | 1,000 | 1,480 | 2″ RF FLG ANSI 600 |
| 3M1480 | 3,000 | 1,480 | 2″ RF FLG ANSI 600 |
| 5M1480 | 5,000 | 1,480 | 3″ RF FLG ANSI 600 |
| 7M1480 | 7,000 | 1,480 | 3″ RF FLG ANSI 600 |
| 11M1480 | 11,000 | 1,480 | 4″ RF FLG ANSI 600 |
What to Know About High-Pressure Models
These meters are typically used with remote volume correctors or advanced units like the IMC/W2, especially when used in custody transfer applications.
Exact flow ratings vary slightly based on gas pressure and specific installation, but the naming still gives a general indication (1M = 1,000 ACFH, 3M = 3,000 ACFH, etc.).
These models often use a cartridge-style internal unit housed in a pressure-rated body.
ANSI flange ratings determine what pressure class the meter can handle safely. Always match to your system’s max operating pressure and local code requirements.
HPC Internal Bypass Valve: Function and Importance
HPC meters are equipped with an internal bypass valve, a crucial component that facilitates safe and efficient meter operation during maintenance and system checks.
Function of the Internal Bypass Valve:
- Meter Pressurization: During startup, the internal bypass valve allows for gradual pressurization of the meter. By partially opening this valve, gas can flow into the meter slowly, preventing sudden pressure surges that could damage internal components.
- Flow Initiation: Throttling the bypass valve might be necessary to initiate gas flow through the meter, ensuring that the impellers begin rotating smoothly.
Importance of the Internal Bypass Valve:
- Prevents Over-Speed Conditions: Rapid pressurization can cause the meter’s impellers to over-speed, potentially leading to mechanical damage. The bypass valve helps control the rate of pressurization, mitigating this risk.
- Facilitates Maintenance: During maintenance or calibration, the bypass valve allows gas to flow around the meter, enabling work to be performed without interrupting the overall gas supply.
Incorporating an internal bypass valve enhances the meter’s operational safety and longevity, ensuring accurate measurements and reliable performance in gas distribution systems.
HPC Cartridge Design: Easy Maintenance & Replacement
HPC meters feature a removable cartridge design. This modular approach offers major advantages for serviceability and long-term maintenance.
What Is the Cartridge?
The cartridge is the heart of the HPC gas meter—it houses the precision-machined impellers, timing gears, bearings, and seals. Furthermore, instead of building these components directly into the meter body, Dresser assembles them as a single, self-contained unit.
Why It Matters:
Field-Proven Durability: Cartridges are designed with tight tolerances and long-life bearings, but like any mechanical component, they do wear over time—especially in high-flow or dirty gas environments. Having a replaceable core allows for straightforward lifecycle maintenance.
Simplified Repairs: If the meter needs to be serviced, technicians can remove the entire internal measuring unit (the cartridge) without unbolting the meter from the pipeline. This drastically reduces downtime and eliminates the need for hot work or full line depressurization.
Interchangeability: For many models, a worn or damaged cartridge can be replaced with a factory-calibrated replacement. This means the meter body can stay in place while the internal measuring components are swapped out—minimizing disruption and cost.
Calibrated Accuracy: Replacement cartridges are manufactured and tested at the factory to meet original specifications. This ensures continued measurement accuracy without the need for field calibration or adjustments.
Where It’s Used:
You’ll find cartridge-style construction in many HPC (High Pressure Cartridge) models, as well as in some standard line sizes. These include models like 1M300, 3M740, 5M1480, and others, which operate under high stress or in critical service locations.
📄DOWNLOAD HPC METER MANUAL
1M/3M HPC Meter Cartridge Changeout
RESOURCES
How to Install a Dresser Roots Gas Meter
📄Download B3 Series IOM Complete Instructions
Installing a Dresser Roots rotary gas meter requires proper orientation, leveling, debris protection, and slow pressurization. Following these steps ensures accurate measurement and protects the meter from overspeed or damage.
1. Choose the Correct Piping Orientation
Top Inlet (Preferred)
- Gas flows top-to-bottom in a vertical run.
- Best for passing pipe scale and debris through the meter.
- Reduces the chance of foreign material collecting in the measuring chamber.
Side Inlet (Horizontal)
- Acceptable alternative when vertical piping is not available.
- Must still be installed level and free of piping strain.
Do not install the meter lower than the outlet piping, or condensate and contaminants may pool inside the meter body.
2. Use a Strainer Upstream (Required by Dresser)
A 100-mesh stainless steel screen is strongly recommended.
- Y-strainer (easiest to clean, durable/rugged)
- Gasket strainer (space-saving option, inexpensive)
Do not place a lubricated plug valve directly upstream — grease can migrate into the meter and stop impeller rotation.
3. Add a Bypass Line (Recommended)
Dresser recommends installing a bypass loop and tees on both sides of the meter when possible.
This allows:
- Field proving
- Maintenance
- Oil changes
- Testing
- Meter replacement
— without shutting down the entire gas supply.
5. Position and Level the Meter Correctly
During installation:
- Ensure the upstream piping is clean
- Remove yellow inlet & outlet protective caps
- Make sure the oil sight glasses are horizontal. This ensures proper lubrication.
- Level the meter within 1/16 inch per foot (5 mm/m) side-to-side and front-to-back.
Never install a gas meter with the “head” lifted up towards the sky. It should always remain level (parallel) with the ground. If you are next to a wall or have space limitations, consider a reverse flow application if required. Dresser has ways to have the odometer count up when flow remains against the arrow.
6. Bolt the Meter Without Piping Strain
- Use proper pipe supports — do not allow the meter body to carry load.
- Bolt flanges evenly in a cross-pattern.
- Use correct torque values:
Torque Values (Lubricated Bolts):
- 8C–16M: 55 ft-lbs (5/8″ Bolt Diameter)
- 23M232: 55 ft-lbs (5/8″ Bolt Diameter)
- 23M175–56M: 104 ft-lbs (3/4″ Bolt Diameter)
- 1M300: 104 ft-lbs (3/4″ Bolt Diameter)
- 3M300: 55 ft-lbs (5/8″ Bolt Diameter)
- The maximum recommended torques 80 foot pounds (108 Newton-Meters) for all HPC Meters.
8. Do Not Add Oil Until After Full Installation
Per Dresser:
“Do not fill the oil reservoirs until the meter has been permanently installed and is ready for service.”
Add oil only after:
- The meter is permanently installed
- All connections are tightened
- The system is ready for commissioning
Fill each reservoir mid-way in the sight glass. Use only approved ROOTS™ meter oil. Do not add oil to the impellers, gears, or head.
9. Install a Restricting Orifice Plate (If Needed)
If there is a possibility of overspeed conditions:
- Install a restricting orifice plate 2–4 pipe diameters downstream of the meter.
This protects the impellers from exceeding rated RPMs.
📄 ROOTS Orifice Plate Datasheet
Summary
To install a Dresser Roots gas meter correctly:
- Use top-inlet vertical flow when possible. Horizon
- Install a 100-mesh strainer upstream.
- Add a bypass loop and test tees when possible.
- Level the meter within 1/16” per foot.
- Bolt flanges evenly and avoid pipe strain.
- Verify free impeller rotation before pressurizing.
- Add meter oil only after installation half-way to each sightglass.
- Pressurize slowly (max 5 psig/second).
This ensures accuracy, prevents overspeed damage, and keeps your installation within Dresser’s (1 year) warranty requirements.
Roots Gas Meter Start-Up Process
Starting up a Dresser Roots rotary gas meter must be done slowly to avoid overspeeding the impellers. Follow these manufacturer-recommended steps:
📄Download Start-up Guide PDF
1. Fill Oil Reservoirs
After the meter is installed:
- Fill both reservoirs to the mid-point of the sight glass
- Use approved Dresser ROOTS™ meter oil
- Do not add oil to the impeller cavity or drive mechanism
2. Verify System Safety and Configuration
- Confirm MAOP (Maximum Allowable Operating Pressure)
- Confirm a strainer is installed upstream
- Ensure valves downstream are open to allow controlled pressurization
3. Pressurize Slowly
To protect the meter’s internal components:
- Pressurize at a rate of no more than 5 PSIG per second
- Open bypass and downstream valves
- Crack the inlet valve slightly to allow gradual fill
This prevents sudden surges that could overspeed the meter.
4. Check for Proper Meter Rotation
- On mechanical models: confirm the black-and-white RPM wheel is turning smoothly
- On IMCW2/MC3 units: confirm a blinking black indicator dot
- Listen for rubbing, scraping, or unusual noises
If anything sounds abnormal:
- Close inlet
- Place system back on bypass
- Depressurize and inspect the piping and strainer
5. Fully Open the Inlet Valve
Once the meter is stable and rotating correctly:
- Open the inlet valve fully
- Slowly close the bypass valve
- Confirm steady rotation and correct differential pressure
6. Leak Test the Installation
Use an approved leak detection method (soap solution or electronic detector) and check:
Accessory ports, All flanges, Index connections, Bypass and inlet valves
How to Add Meter Oil to Roots Gas Meter
CAUTION: Bleed off the line pressure before removing the oil fill or drain plugs from the meter.
Dresser Roots gas meters use oil to lubricate the bearing reservoirs. Oil should not be added until after the meter has been permanently installed and ready for service. Moreover, ROOTS meters are shipped with enough oil for initial fill, typically the maximum required for a top-inlet configuration plus a small margin.
ROOTS™ Meter Oil is a non-hazardous, environmentally friendly lubricant:
- Not rated hazardous by OSHA or the EPA.
- Contains no SARA Title III–reportable chemicals.
- Red-dyed for visibility but does not contain toxic Ethyl Benzene.
- Compatible with prior approved Dresser oils
(Versi-Temp 2, Shell Tellus T15, and Grade 50/Shell Diala AX).
TOP INLET
8C-16M
SIDE INLET
8C-16M
23M-56M
Oil Sight Gauges will be parallel and on
the bottom for top inlet and side inlet
HIGH-PRESSURE MODELS NOTE: The meter oil fill plug is located on the gear end side. This meter has oil reservoirs in both ends connected by an oil path tube. Please allow time for the oil to traverse the oil path tube and fill the counter end reservoir before assuming the meter is full of oil.
| Model | Side Inlet | Top Inlet |
|---|---|---|
| 8/11/15C | 0.8 oz (23.7 ml) | 3.0 oz (88.7 ml) |
| 2/3/5M | 1.25 oz (37 ml) | 7.6 oz (224.8 ml) |
| 7/11/16M | 3.0 oz (88.7 ml) | 21.85 oz (646.2 ml) |
| 23175/38/56M | 40.2 oz (1.2 L) | 154 oz (4.55 L) |
| 23M232 | 3.4 oz (100.6 ml) | 21.8 oz (644.7 ml) |
| 1M740/1480 | 4.2 oz (124 ml) | 11 oz (325 ml) |
| 3M740/3M1480 | 2.8 oz (83 ml) | 7.2 oz (213 ml) |
| 5M1480 | 18 oz (532 ml) | 37 oz (1094 ml) |
| 7M1480 | 14 oz (414 ml) | 29 oz (858 ml) |
| 11M1480 | 14 oz (414 ml) | 34 oz (1006 ml) |
Basic Oil Service Rules
- Use approved Dresser ROOTS™ Meter Oil only (MADE IN THE USA!)
- Depressurize or bypass the meter.
- Remove the oil fill plugs and empty the reservoirs.
- Refill each reservoir to the mid-sight-glass level, then reinstall plugs securely. DO NOT OVERFILL
- Finally, slowly restore flow (5 PSI per second); the oil slingers will lubricate the bearings automatically.
- Check oil monthly.
- Change oil every 3–5 years, or sooner if dark or contaminated.
VIDEO TUTORIAL:
Replacing Meter Oil
CAUTION: Bleed off the line pressure before removing the oil fill or drain plugs from the meter.
Make sure the meter is bypassed and depressurized. Remove the fill plugs and fill each reservoir to the middle of the sight glass. Replace fill plugs securely before pressurizing the meter. Once gas flow resumes, the impellers will rotate and the internal oil slingers will distribute lubricant to the bearings. Draining the old oil is optional—Dresser ROOTS oils are fully compatible and can be blended. However, draining is recommended if oil clarity is important.
To Replace Oil:
- Depressurize or bypass the meter.
- Remove the oil fill plugs and empty the reservoirs.
- Refill each reservoir to the mid-sight-glass level, then reinstall plugs securely. DO NOT OVERFILL
- Finally, slowly restore flow (5 PSI per second); the oil slingers will lubricate the bearings automatically.
HIGH-PRESSURE MODELS NOTE: The meter oil fill plug is located on the gear end side. This meter has oil reservoirs in both ends connected by an oil path tube. Please allow time for the oil to traverse the oil path tube and fill the counter end reservoir before assuming the meter is full of oil.
| Model | Side Inlet | Top Inlet |
|---|---|---|
| 8/11/15C | 0.8 oz (23.7 ml) | 3.0 oz (88.7 ml) |
| 2/3/5M | 1.25 oz (37 ml) | 7.6 oz (224.8 ml) |
| 7/11/16M | 3.0 oz (88.7 ml) | 21.85 oz (646.2 ml) |
| 23175/38/56M | 40.2 oz (1.2 L) | 154 oz (4.55 L) |
| 23M232 | 3.4 oz (100.6 ml) | 21.8 oz (644.7 ml) |
| 1M740/1480 | 4.2 oz (124 ml) | 11 oz (325 ml) |
| 3M740/3M1480 | 2.8 oz (83 ml) | 7.2 oz (213 ml) |
| 5M1480 | 18 oz (532 ml) | 37 oz (1094 ml) |
| 7M1480 | 14 oz (414 ml) | 29 oz (858 ml) |
| 11M1480 | 14 oz (414 ml) | 34 oz (1006 ml) |
List of Acceptable Gases for ROOTS meters:
Dresser meters are suitable for handling most types of clean, dry, common gases at either constant or varying flow rates. The meter is not suitable for handling liquids. Measurement accuracy
and life expectancy may be affected by dirt or other types of foreign material in the gas stream. For a list of acceptable dry gases, consult factory.
- Air
- Argon
- Butane
- Carbon Dioxide (dry)
- Carbon Monoxide (dry)
- Ethane
- Ethylene (C2H4)
- Helium
- Methane (Natural Gas)
- Neon
- Nitrogen
- Propane
Special Service Meters
- Methane
NON-APPROVED DRY GASES
- Hydrogen
- Oxygen
Restricting Orifice Plate
While Dresser Roots gas meters are built for long-term precision, they still need protection from pressure surges and sudden flow spikes that can cause internal damage. That’s where a restricting orifice plate comes in.
What Does It Do?
A restricting orifice plate is a thin, machined metal disk with a small hole “bored” in the center. It is installed downstream of the gas meter (2 – 4 pipe diameters – roughly 1 foot) and works by limiting the amount of gas that can pass through the system during peak conditions.
If too much gas tries to rush through the meter all at once, the orifice plate creates a controlled restriction that prevents the meter from exceeding its rated speed, also known as “over-speeding.” If gas flows through the meter too quickly, the timing gears can overspin and jam up.
What it does not do:
- It does not measure flow.
- It does not calculate differential pressure for billing.
Key Guidelines from Dresser Utility Solutions
- Install the orifice plate 2 to 4 pipe diameters downstream (roughly 1 foot) from the meter outlet.
- For meters rated at 175 PSIG or less, plates are sized to trigger critical flow at approximately 120% of the meter’s rated capacity.
- For high-pressure meters (MAOP above 200 PSIG), the orifice plate is sized at 100% of the meter’s capacity.
- Caution: These orifice sizes are recommended as safety devices only to protect the meter from over-ranging.
- Equally important, if critical flow is reached often or for extended periods of time, the next larger size meter should be installed.
ROOTS Restricting Flow Orifice Plates
Dresser offers pre-sized orifice plates matched to every meter model. These plates are available in various thicknesses and orifice diameters depending on meter size and pressure class.
| Model | Pipe Size (in.) | Plate O.D. (in.) | Orifice Size (in.) | Plate Thickness (in.) | Part Number |
|---|---|---|---|---|---|
| 8C175-LMMA | 1½ | 3-9/32 | 17/64 | 1/8 | 010847-024 |
| 8C175 | 2 | 4-1/32 | 9/32 | 1/8 | 010847-032 |
| 11C175 | 2 | 4-1/32 | 21/64 | 1/8 | 010847-033 |
| 15C175 | 2 | 4-1/32 | 3/8 | 1/8 | 010847-034 |
| 2M175 | 2 | 4-1/32 | 7/16 | 1/8 | 010847-035 |
| 3M175 | 2 | 4-1/32 | 17/32 | 1/8 | 010847-001 |
| 5M175 | 3 | 5-9/32 | 11/16 | 1/8 | 010847-065 |
| 7M175 | 3 | 5-9/32 | 13/16 | 1/8 | 010847-002 |
| 11M175 | 4 | 6-25/32 | 1 | 1/8 | 010847-012 |
| 16M175 | 4 | 6-25/32 | 1-7/32 | 1/8 | 010847-003 |
| 23M232 | 4 | 6-25/32 | 1-11/32 | 1/8 | 010847-060 |
| 23M175 | 6 | 8-21/32 | 1-15/32 | 1/4 | 010847-004 |
| 38M175 | 6 | 8-21/32 | 1-29/32 | 1/4 | 010847-005 |
| 56M175 | 8 | 10-29/32 | 2-1/4 | 5/16 | 010847-006 |
| 102M125 | 10 | 13-9/32 | 3-1/8 | 3/8 | 010847-007 |
| 1M300 | 1½ | 3-9/32 | 9/32 | 1/8 | 010847-030 |
| 3M300 | 2 | 4-1/32 | 17/32 | 1/8 | 010847-031 |
| 1M740 | 2 | 4-9/32 | 0.277 | 1/4 | 010847-040 |
| 1M1480 | 2 | 4-9/32 | 17/64 | 1/4 | 010847-041 |
| 3M740 | 2 | 4-9/32 | 31/64 | 1/4 | 010847-042 |
| 3M1480 | 2 | 4-9/32 | 7/16 | 1/4 | 010847-043 |
| 5M1480 | 3 | 5-13/16 | 19/32 | 1/4 | 010847-053 |
| 7M1440 | 3 | 5-13/16 | 23/32 | 1/4 | 010847-016 |
| 7M1480 | 3 | 5-13/16 | 45/64 | 1/4 | 010847-052 |
| 11M1480 | 4 | 7-5/8 | 57/64 | 1/4 | 010847-076 |
Note: Custom orifice plates can be ordered for exact conditions.
📄 ROOTS Orifice Plate Datasheet
Why Your Dresser Roots Gas Meter Stopped Counting (and How to Fix It)
If your Dresser Roots gas meter has stopped turning, isn’t registering usage, or won’t start during commissioning, debris in the measuring chamber is often the cause—especially when an upstream strainer is missing or improperly installed. In some cases, excessive flow or rapid pressurization can overspeed the meter, causing the precision-timed impellers to bind or lose proper timing.
There are two accepted methods for clearing debris or freeing the figure-eight impeller gears, depending on severity.
Method 1: Clearing Debris with the Meter Installed in the Pipe
For start-up issues or light binding, debris can sometimes be cleared without removing the meter from the pipeline.
First, shut off the gas supply or place the meter in bypass and fully depressurize the meter set. Never attempt this procedure while the meter is under pressure.
On the timing-gear end of the meter (opposite the register index or “head”), remove the access plug located on the end of the meter (commonly a 5/16″ hex). Using the appropriate hex wrench, carefully engage the gear clamp and slowly rotate the impellers clockwise only, or gently back and forth, checking for free movement.
Manufacturer guidance:
- If binding is felt, stop immediately
- Do not force the impellers
- Do not rotate counter-clockwise
If the impellers begin to move freely, reinstall the access plug (torqued to approximately 6–7 ft-lbs), restore oil if required, and proceed with the normal meter start-up procedure.
Lastly, if binding remains, the meter must be removed for bench inspection (Method 2).
Method 2: Bench Cleaning (Severe or Persistent Debris)
If debris cannot be cleared while the meter remains in the pipeline, the meter must be removed and cleaned on a workbench.
Next, drain all meter oil while the meter is still installed. The oil reservoirs are not isolated from the measuring chamber, and rotating or handling the meter with oil present can result in oil contamination or spillage.
Once removed, gently check impeller movement by hand. On clean or lightly contaminated meters, the impellers may rotate freely with minimal force—even light airflow. If resistance is present, debris is likely lodged in the measuring chamber.
Approved cleaning methods include:
- Low-pressure compressed air
- Small amounts of 91% isopropyl alcohol applied with a spray bottle
- Cotton swabs (Q-tips) for carefully removing fine debris or metal shavings
Use minimal liquid and allow the meter to fully dry. Never use metal tools such as screwdrivers, picks, or scrapers, as these can damage the precision-timed impellers and internal surfaces.
After cleaning, reinstall the meter, refill with approved meter oil, and return the unit to service using the standard start-up procedure.
If binding remains after cleaning, contact your local distributor for RMA or factory repair. Rotary meter repairs are typically performed at the Dresser facility in Houston, TX and can cost up to two-thirds the price of a new meter.
Important Notes
- Never clean or flush a Roots gas meter while pressurized
- Never rotate impeller timing components counter-clockwise via the access plug
- Forcing rotation or reversing impellers can cause internal damage and void warranty
- If debris issues recur, install or inspect an upstream 100-mesh strainer
VIDEO TUTORIAL:
FAQ
Common Questions About Dresser Roots Gas Meters
What is the best flow meter for natural gas?
The best flow meter for natural gas depends on the application. For many commercial and industrial gas systems, a Roots rotary positive displacement meter is a top choice because it measures actual gas volume directly, handles wide flow ranges well, and does not require long straight pipe runs. Larger transmission or specialty applications may call for ultrasonic, turbine, Coriolis, or differential-pressure meters instead.
How do I size a gas meter?
Gas meters are sized based on flow rate, not pipe size. You’ll need to know your maximum gas flow in CFH or BTU/hr, along with the available line pressure, which is critical for proper sizing. Pipe size is only relevant for installation and flange connections, not for selecting meter capacity. Once the maximum flow and pressure are known, the meter is selected so it operates within its rated range and maintains accuracy across the expected flow conditions.
What’s the Difference Between ACFH and SCFH?
ACFH (Actual Cubic Feet per Hour) measures the gas volume flowing through the meter at current line pressure and temperature. In other words, it shows what physically passes through the pipe at that “actual” moment.
SCFH (Standard Cubic Feet per Hour), however, corrects that volume to a fixed “standard” temperature (60 Deg.) and pressure (14.73 PSIA). Because utilities bill on energy content, they typically rely on SCFH instead of ACFH.
Therefore, the meter itself measures actual volume, while a temperature or pressure corrector converts that reading into standard volume for billing and reporting.
Can a Roots Meter Be Used for Propane?
Yes — Dresser Roots rotary meters can measure propane when properly specified for LP service.
However, you must size the meter differently. Because propane contains about 2.5 times more BTUs per cubic foot than natural gas, the required flow rate changes significantly. As a result, engineers often apply a 2.5× correction factor when converting natural-gas loads to propane service.
Can a Roots Meter Measure Liquid?
No — Dresser Roots rotary meters are designed for clean, dry gas service only and cannot measure liquids.
For contaminated or corrosive gas streams—such as landfill gas, digester gas at wastewater treatment plants, or sewage gas—specify Special Service Meter (SSM) constructions built for those conditions.
How Often Should a Gas Meter Be Calibrated?
Roots meters hold accuracy extremely well, so most installations run for years without recalibration.
That said, utilities and industrial users typically follow local regulations or internal measurement standards, which often call for periodic proving or verification every few years. In custody-transfer service, operators usually test meters more frequently.
Moreover, operators can perform in-place differential-pressure checks to confirm meter health without removing the unit. If readings drift outside expected limits, then the meter should go in for service or factory recalibration.
What If a Roots Meter Is Installed for Reverse Flow?
In some installations, space limitations force gas to flow opposite the arrow cast into the meter body—such as when a meter sits close to a wall or piping must enter from the outlet. In those cases, the arrow located on the blue tag (meter body) will point opposite the actual gas direction .
When this happens, a standard mechanical register will count backwards, which creates billing and reporting problems.
Fortunately, Dresser offers two solutions:
Electronic Correctors (IMC/W2)
By default, the IMC/W2 Micro Corrector totals volume in both directions (“Forward + Reverse” in MCUT software). As a result, it will continue counting upward even when gas flows opposite the body arrow.
Mechanical Indexes (CTR, Standard Registers)
If the meter uses a mechanical index, you can replace the odometer with a Reverse-Flow Counter (P/N: 059195-000). This special register allows the display to count up while gas travels in the reverse direction, eliminating the need to re-pipe the installation.
Do You Sell Howden ROOTS Blowers or Compressors?
No. Process Valve & Equipment supplies Dresser ROOTS rotary gas meters, gas meter accessories, and gas measurement products. We do not sell, quote, repair, or support Howden ROOTS blowers, ROOTS vacuum pumps, rotary lobe blowers, or compressors.
Although the ROOTS name has been used in both gas measurement and blower/compressor markets, these are separate product categories today. Howden ROOTS is separate from Dresser ROOTS gas meters.
If you need Dresser ROOTS gas meters, meter oil, pulsers, micro corrector accessories, flange kits, strainers, or related gas measurement products, we can help.
Who Manufactures Roots Gas Meters?
Dresser ROOTS gas meters are made by Dresser Utility Solutions, a U.S.-based company with roots dating back to 1880. Dresser began in Bradford, Pennsylvania, where it still maintains a major presence in gas and industrial products.
Today, Dresser Utility Solutions manufactures ROOTS positive displacement rotary gas meters, ROOTS and Actaris gas regulators, Flow Safe pressure relief valves, RCS and ANDCO actuators, pipeline and coupling products, and other equipment for utility and industrial applications. Headquartered in Houston, Texas, the company serves customers worldwide.
Originally known as Dresser NGS (Natural Gas Solutions), previously owned by Baker Hughes, and GE, the company rebranded to Dresser Utility Solutions in 2021 but continues its century-plus tradition of manufacturing highly engineered metering products.
Because Dresser’s meters meet stringent international measurement and safety standards, utilities and industrial users rely on them for accurate flow measurement from city gates and plant boundaries to custody transfer points.
New Product Highlight
Coming Soon: MC3 Guardian & MC3 Nexus Smart Correctors
Launching later this year, the MC3 Guardian and MC3 Nexus are Dresser Utility Solutions’ next-generation electronic volume correctors designed to modernize Roots gas meter installations.
These upcoming devices focus on what utilities and industrial operators want most: digital connectivity, remote visibility, rapid proving, and smarter diagnostics — all packaged in a rugged, field-ready platform.
Digital Communication
When released, the MC3 platform will support an extensive list of communications options, including:
• Cellular modem compatibility
• Internal modem options
• IrDA and Bluetooth
• IPv4 Ethernet ready
• CoAP (IoT web protocol) ready
• Interfaces for Itron MV-90 xi and Autosol ACM 8.0
In addition, the MC3 family will integrate with leading AMI/AMR systems from Itron, Landis+Gyr, Sensus, Aclara, and others.
Operator-Focused Design
Dresser built the MC3 series specifically for field technicians and utility crews:
• Metal enclosure for enhanced service life
• Touchscreen parameter changes for fast configuration updates
• Straightforward meter installation process
• Plug-and-play pressure transducers and temperature probes
• Time-saving proving of integral correctors
• Dedicated communications battery to protect metrology data
• Simplified battery exchange in the field
• Convenient access through tablet, smartphone, or computer
In addition, technicians benefit from:
• Multi-line programmable displays for improved readability
• Clear, descriptive alarm messages for rapid response
• Mobile tools for iOS, Android, and Windows
• Field-friendly service access
• Secure non-volatile memory with audit trails
Pulse and I/O capability will include:
• Up to 6 Form A and 2 Form B outputs (supports Form C)
• Serial, Bluetooth, and IrDA interfaces
Rugged for Utility Service
The MC3 platform will also carry approvals designed for harsh field environments:
• CSA C/US Class I, Division 2, Group D
• IP66 and NEMA 4X enclosure ratings
📄View Datasheet
Where to Buy Dresser Roots Gas Meters
Largest Dresser Roots Stocking Distributor
ESTABLISHED IN 1951– Celebrating 75 Years!
Lifetime Service & Support
- Application-first approach – correct meter sizing for your application, right from the start
- Deep technical expertise – gas metering is what we do, not a side offering
- Complete Dresser Roots product line – meters, accessories, parts, and new releases
- In-stock inventory with same-day shipping on many common meter models
- One-stop shop – regulators, pressure & temperature sensors, gas detectors, pipe insulation, and much more
When you buy a Dresser Roots gas meter from Process Valve, you’re not just purchasing equipment — you’re gaining a long-term technical partner who helps you get it right before, during, and after installation.