Series-RM

Supported Applications

The Dwyer Series RM Rate-Master® Polycarbonate Flowmeters are direct reading precision flowmeters designed for general use with compatible gases and liquids. The series is specified for applications involving air, water, or other media that do not include caustic solutions, antifreeze (ethylene glycol), or aromatic solvents. These units provide a visual indication of flow rate using 2" (51 mm), 5" (127 mm), and 10" (254 mm) scales.

For systems with fluctuating inlet or discharge pressure, the series supports optional regulator kits to maintain a nearly constant differential pressure. The RKA kit is designed for use with Series VFA flowmeters up to 200 SCFH, while the RK-RMB and RK-VFB kits are available for other configurations.

Operating Conditions & Performance

The series operates within a process temperature limit of 130°F (54°C) and supports pressures up to 100 psi (6.9 bar). Accuracy varies by model size: Model RMA offers 4% FS, Model RMB provides 3% FS, and Model RMC delivers 2% FS.

Measurement ranges span multiple scales for air and water:

• Air (SCFH): From 0.05 to 1800 SCFH across various scale configurations.
• Air (CC/min, LPM, SCFM): Ranges include 5 to 10000 CC/min and up to 30 SCFM.
• Water: Scales cover ranges from 5 to 2500 CC/min, GPH (up to 1800), and GPM (up to 7).

The design ensures high repeatability through precision injection molding around a tapered pin. Installation requires mounting in a vertical position with the inlet connection at the bottom rear and outlet at the top rear, away from strong chlorine atmospheres or solvents such as benzene, acetone, and carbon tetrachloride.

Configuration Options

The Series RM is available in three primary models—RMA, RMB, and RMC—which differ by scale length, process connection size, and accuracy. The series supports a wide array of configuration options to meet specific installation needs:

• Process Connections: 1/8" female NPT (Model RMA), 1/4" female NPT (Model RMB), or 1/2" female NPT (Model RMC).
• Valve Options: Models can be ordered with optional precision metering valves, including SSV and TMV variants.
• Scales & Markings: Arbitrary scales (-ARB), aluminum tags (-AT), or without logo (-WL) are available. Adjustable pointer flags (APF for RMA, BPF for RMB, CPF for RMC) can be added to specific models.
• Materials & Seals: Wetted materials include a polycarbonate body with Neoprene and Buna-N O-rings. Metal parts are stainless steel; floats vary by range (SS, black glass, aluminum, K monel, tungsten carbide). PTFE valve seats (-PTFE) and fluoroelastomer O-rings (-VIT) are offered as options.
• Service Options: NIST traceable calibration certificates (-NIST), special cleaning (-SPCL), body-only units (-BO, -BOV).

The flowmeter bodies within a given series can be instantly interchanged without disturbing the piping, facilitating range changes and maintenance.

Key Product Differences

Differences between models are defined by physical dimensions and connection sizes. Model RMA is the smallest unit with an overall height (A) of 4-9/16" [115.90 mm] and a weight of 4 oz (113.4 g). Model RMB measures 8-1/2" [215.90 mm] in height and weighs 13 oz (368.5 g). The largest, Model RMC, has an overall height of 15-1/8" [384.20 mm] and a weight of 29 oz (1105.6 g).

Panel cutouts for flush mounting vary by model: RMA requires a high dimension of 4-5/8", while RMB and RMC require larger openings corresponding to their scale lengths. Surface mount configurations utilize specific pipe and bolt hole sizes detailed in the dimensional tables.