The Dwyer RMA-21-SSV-BSPT is a Rate-Master Series RM polycarbonate variable area flowmeter that reads 1 to 10 LPM air on a 2 in. (51 mm) direct-reading scale. It is fitted with a stainless steel metering valve and has BSPT process connections.
Specifications verified October 12, 2026 against Dwyer DS-RM Rev. 3 (2/21), Bulletin F-43 (FR# 440197-00 Rev. 26, 8/23) and the Dwyer Series RM product page.
Best For
- Direct reading of 1 to 10 LPM air with no conversion charts
- Air samplers and gas analyzers
- Pollution monitors
- Cabinet purging
- Medical equipment
- Panel mounted, surface mounted or piping-supported installations
Warranty
DwyerOmega limited warranty: free from defects in material and workmanship under normal use for one year from delivery, or such other period as specified in a product-specific warranty supplied with the product. Team Zot supports warranty claims at 855-825-2811 or sales@zotsupply.com.
Key Features
Direct-Reading LPM Scale
The 2 in. (51 mm) scale reads 1 to 10 LPM air directly, eliminating troublesome conversions.
Stainless Steel Metering Valve
Turn clockwise to reduce flow and counter-clockwise to increase it. A nylon insert in the stem threads gives a firm touch and holds the setting against vibration. Designed for flow adjustment, not shut-off.
Stainless Steel Backbone
Absorbs piping torque to reduce installation damage and cost.
Shatter-Proof Polycarbonate Body
Durable body built for long operating life.
High Repeatability
Precision injection molding around a precision tapered pin, with integral flow guides that stabilize float movement.
Graduations on Both Sides
Scale graduations on both sides of the indicating tube give an instant flow reading.
ZOT Supply is an authorized distributor of Dwyer products.
Technical Specifications
| Series | Rate-Master Series RM, Model RMA |
| Flow Range | 1 to 10 LPM |
| Calibrated Media | Air |
| Scale Length | 2 in. (51 mm) |
| Accuracy | 4% FS |
| Valve | Stainless steel valve (SSV) |
| Process Connection | BSPT |
| Pressure Limit | 100 psi (6.9 bar) |
| Temperature Limit | 130°F (54°C) |
| Service | Compatible gases and liquids |
| Wetted Materials | Body: polycarbonate; O-rings: neoprene and Buna-N; metal parts: stainless steel; float: stainless steel, black glass, aluminum, K monel or tungsten carbide depending on range |
| Calibration | Factory calibrated |
| Mounting Position | Vertical, inlet at bottom rear, outlet at top rear |
| Mounting Options | Through-panel (flush), surface mounted, or supported on piping |
| Panel Cutout (Flush Mounting) | 4-5/8 in. high x 7/8 in. wide (11.75 x 2.22 cm) |
| Mounting Holes | 10-32 thread |
| Clamp Bolt Torque | 5 in-lb maximum |
| Dimensions (see drawing) | A 4-9/16 in. [115.90 mm]; F 1-3/16 in. [30.16 mm]; J (back width) 3/4 in. [19.05 mm]; K 4-13/16 in. [122.20 mm]; L 1 in. [25.40 mm] |
| Weight | 4 oz (113.4 g) |
| Compliance | Meets the technical requirements of EU Directive 2011/65/EU (RoHS II) |
Documentation
Frequently Asked Questions
What flow range does the Dwyer RMA-21-SSV-BSPT measure?
The Dwyer RMA-21-SSV-BSPT reads 1 to 10 LPM air on a 2 in. (51 mm) direct-reading scale.
How accurate is the Dwyer RMA-21-SSV-BSPT?
Accuracy is 4% of full scale (4% FS).
What are the pressure and temperature limits of the RMA-21-SSV-BSPT?
The RMA-21-SSV-BSPT is rated to 100 psi (6.9 bar) and 130°F (54°C). Do not exceed these limits.
How is the Dwyer RMA-21-SSV-BSPT mounted?
Mount it vertically with the inlet at the bottom rear and the outlet at the top rear. It can be mounted through the panel using a 4-5/8 in. high x 7/8 in. wide (11.75 x 2.22 cm) cutout, surface mounted, or supported on rigid piping. Do not exceed 5 in-lb on the clamp bolts.
Can the valve on the RMA-21-SSV-BSPT be used to shut off flow?
No. The stainless steel valve is designed for flow adjustment only and is not intended as an open/shut-off valve. Turn it clockwise to reduce flow and counter-clockwise to increase flow.
What thread are the process connections on the RMA-21-SSV-BSPT?
The RMA-21-SSV-BSPT has BSPT (British Standard Pipe Taper) process connections.
What fluids should not be used with the RMA-21-SSV-BSPT?
Caustic solutions, antifreeze (ethylene glycol) and aromatic solvents should not be used, and solutions of acids, bases or salts with a pH below 5.0 or above 8.5 should be avoided. Keep the installation away from strong chlorine atmospheres and solvents such as benzene, acetone and carbon tetrachloride.
Can the RMA-21-SSV-BSPT be cleaned without removing the piping?
Yes. First make sure the flowmeter is unpressurized and drained of any liquid. Turn the valve knob counter-clockwise until the threads disengage and withdraw the stem, then remove the four mounting bracket screws and pull the body forward; the piping connections stay intact. Clean the flow tube and body with pure soap and water and a soft brush.
