The Dwyer VFA-2-SSV is a Visi-Float Series VF acrylic variable area flowmeter (Model VFA) with a 2 in. direct-reading scale for 0.2 to 2 SCFH air. It is fitted with a stainless steel metering valve and has 1/8 in. female NPT back connections.
Specifications per Dwyer DS-VF Rev. 1 (8/20) and Dwyer Bulletin F-33 Rev. 8 (7/20).
Best For
- Direct reading of 0.2 to 2 SCFH air with no conversion charts
- Air samplers and gas analyzers
- Pollution monitors
- Cabinet purging
- Medical and laboratory equipment
- Setting and holding a flow rate with the integral metering valve
Warranty
DwyerOmega warrants products to be free from defects in material and workmanship under normal use for one year from delivery to the buyer, or such other period, if any, as specified in the product-specific warranty typically supplied with the product.
Key Features
Direct-Reading SCFH Scale
The 2 in. scale reads 0.2 to 2 SCFH air directly. Scales are hot stamped into the plastic, eliminating troublesome conversions and increasing operating life.
Stainless Steel Metering Valve
Integral stainless steel precision metering valve. A nylon insert in the stem threads gives a firm touch and prevents a change of setting due to vibration. Designed for flow adjustment, not shut-off.
Precision Tapered Bore
A precision machined tapered bore enables high repeatability.
White Background
A white background improves float visibility, increasing reading accuracy.
Back Connections
1/8 in. female NPT back connections. Metal mounting inserts allow the meter to be supported directly by system piping.
Solid Acrylic Body
Cut and precision machined from a solid, clear acrylic block, allowing complete visual inspection.
ZOT Supply is an authorized distributor of Dwyer products.
Technical Specifications
| Series | Visi-Float Series VF, Model VFA |
| Model Code | VFA-2-SSV |
| Flow Range | 0.2 to 2 SCFH |
| Scale Media | Air |
| Scale Length | 2 in. (50.8 mm) |
| Accuracy | 5% FS |
| Valve | Stainless steel metering valve (-SSV) |
| Process Connection | 1/8 in. female NPT back connections |
| Pressure and Temperature Limits | 100 psig (6.9 bar) @ 120°F (48°C) |
| Service | Compatible gases and liquids |
| Wetted Materials | Body: acrylic plastic; O-ring: Buna-N; Metal parts: brass; Valve: stainless steel; Float: SS, black glass, aluminum or K monel, depending on range |
| Mounting Position | Vertical, inlet connection at the bottom and outlet at the top |
| Mounting | Panel surface mount with 10-32 threaded inserts, or supported on the connecting piping |
| Calibration | Factory calibrated |
| Weight | 4.0 to 4.8 oz (0.11 to 0.14 kg) |
Documentation
Frequently Asked Questions
What flow range does the Dwyer VFA-2-SSV measure?
The VFA-2-SSV reads 0.2 to 2 SCFH of air directly on a 2 in. (50.8 mm) scale, with 5% FS accuracy.
What process connections does the VFA-2-SSV have?
The VFA-2-SSV has 1/8 in. female NPT back connections.
What are the pressure and temperature limits of the VFA-2-SSV?
With its integral valve, the VFA-2-SSV is rated 100 psig (6.9 bar) @ 120°F (48°C).
How is flow adjusted on the VFA-2-SSV?
Turn the valve clockwise to reduce flow and counter-clockwise to increase flow. Open the valve slowly when starting the system. The valve is designed for flow adjustment only and is not intended as an open/shut-off valve. Do not completely unscrew the valve stem unless the flowmeter is unpressurized and drained of any liquid.
How do I mount the VFA-2-SSV?
Mount it in a vertical position with the inlet connection at the bottom and the outlet at the top, free from vibration. For surface mounting, install the screws through the panel from the rear into the 10-32 threaded inserts; screws must not be longer than the panel thickness plus 1/4 in. The meter can also be supported on the connecting piping only.
How do I correct an SCFH reading for non-standard pressure or temperature?
The SCFH scale is calibrated at standard conditions of 14.7 psia and 70°F (530 R). Measure actual pressure and temperature at the flowmeter exit (at the inlet for vacuum service) and apply Q2 = Q1 x √((P1 x T2) / (P2 x T1)), where Q1 is the observed reading, P1 is 14.7 psia plus gauge pressure, and T1 is 460 R plus the temperature in °F.
How is the VFA-2-SSV cleaned?
Clean the flow tube and body with a little pure soap and water; a soft brush helps. Avoid benzene, acetone, carbon tetrachloride, alkaline detergents, caustic soda and liquid soaps, and avoid prolonged immersion. A little stop cock grease or petroleum jelly on the O-rings helps maintain a good seal.
Is a regulator kit available for the VFA-2-SSV?
Yes. The Dwyer RKA regulator kit fits Series VFA flowmeters and holds a constant pressure differential of approximately 3 ±0.15 psig across the meter, for use where inlet air pressure fluctuates widely and constant flow is required. Supply pressure must be at least 3 psig above the flowmeter discharge. The standard regulator has a brass body, aluminum bonnet and nylon reinforced Buna-N diaphragm.
- Series:
- VF
- Product Type:
- Variable Area Flowmeter
- Media:
- Air
- Flow Range:
- 0.2-2 SCFH
- Connection Type:
- Female NPT
- Connection Size:
- 1/8 in.
- Body Material:
- Acrylic
- Max Pressure:
- 100 psi
- Accuracy:
- 5% FS
- Mounting:
- Vertical
- NIST Calibration:
- Available
