The Dwyer VFA-5 is a Visi-Float Series VF acrylic variable area flowmeter (Model VFA) with a 2 in. direct-reading scale for 2 to 20 SCFH air. It is a standard model without a 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 2 to 20 SCFH air with no conversion charts
- Air samplers and gas analyzers
- Pollution monitors
- Cabinet purging
- Medical and laboratory equipment
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 2 to 20 SCFH air directly. Scales are hot stamped into the plastic, eliminating troublesome conversions and increasing operating life.
Solid Acrylic Body
Cut and precision machined from a solid, clear acrylic block, allowing complete visual inspection.
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.
Factory Calibrated
Each flowmeter is calibrated at the factory.
ZOT Supply is an authorized distributor of Dwyer products.
Technical Specifications
| Series | Visi-Float Series VF, Model VFA |
| Model Code | VFA-5 |
| Flow Range | 2 to 20 SCFH |
| Scale Media | Air |
| Scale Length | 2 in. (50.8 mm) |
| Accuracy | 5% FS |
| Valve | None (standard, no valve) |
| Process Connection | 1/8 in. female NPT back connections |
| Pressure and Temperature Limits | 100 psig (6.9 bar) @ 150°F (65°C); 150 psig (10 bar) @ 100°F (38°C) |
| Service | Compatible gases and liquids |
| Wetted Materials | Body: acrylic plastic; O-ring: Buna-N; Metal parts: brass; 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-5 measure?
The VFA-5 reads 2 to 20 SCFH of air directly on a 2 in. (50.8 mm) scale, with 5% FS accuracy.
What process connections does the VFA-5 have?
The VFA-5 has 1/8 in. female NPT back connections.
What are the pressure and temperature limits of the VFA-5?
The VFA-5 is rated 100 psig (6.9 bar) @ 150°F (65°C); 150 psig (10 bar) @ 100°F (38°C).
Does the VFA-5 include a flow control valve?
No. The VFA-5 is the standard model without a valve. Valved versions add -BV (brass valve) or -SSV (stainless steel valve) after the range code.
How do I mount the VFA-5?
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-5 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-5?
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:
- 2-20 SCFH
- Connection Type:
- Female NPT
- Connection Size:
- 1/8 in.
- Body Material:
- Acrylic
- Max Pressure:
- 150 psi
- Accuracy:
- 5% FS
- Mounting:
- Vertical
- NIST Calibration:
- Available
