The Dwyer VFB-55D-SS is a Visi-Float Series VF acrylic variable area flowmeter (Model VFB) with a 4 in. dual-unit direct-reading scale for 40 to 200 SCFH and 20 to 95 LPM air. It is a standard model without a valve and has 1/8 in. female NPT back connections and stainless steel wetted metal parts.
Specifications per Dwyer DS-VF Rev. 1 (8/20) and Dwyer Bulletin F-33 Rev. 8 (7/20); dual-scale range per the DwyerOmega Series VF model chart (Oct 2026).
Best For
- Direct reading of 40 to 200 SCFH and 20 to 95 LPM 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
Dual-Unit Direct-Reading Scale
The 4 in. scale reads 40 to 200 SCFH and 20 to 95 LPM air directly in both units. Scales are hot stamped into the plastic, eliminating troublesome conversions.
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.
Stainless Steel Wetted Parts
Wetted metal parts are stainless steel in place of the standard brass.
ZOT Supply is an authorized distributor of Dwyer products.
Technical Specifications
| Series | Visi-Float Series VF, Model VFB |
| Model Code | VFB-55D-SS |
| Flow Range | 40 to 200 SCFH and 20 to 95 LPM |
| Scale Media | Air |
| Scale Type | Dual unit (SCFH and LPM) |
| Scale Length | 4 in. (101.6 mm) |
| Accuracy | 3% 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: stainless steel (-SS); 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 | 7.2 to 8.8 oz (0.20 to 0.25 kg) |
Documentation
Frequently Asked Questions
What flow range does the Dwyer VFB-55D-SS measure?
The VFB-55D-SS reads 40 to 200 SCFH and 20 to 95 LPM of air directly on a 4 in. (101.6 mm) dual-unit scale, with 3% FS accuracy.
What process connections does the VFB-55D-SS have?
The VFB-55D-SS has 1/8 in. female NPT back connections.
What are the pressure and temperature limits of the VFB-55D-SS?
The VFB-55D-SS is rated 100 psig (6.9 bar) @ 150°F (65°C); 150 psig (10 bar) @ 100°F (38°C).
Does the VFB-55D-SS include a flow control valve?
No. The VFB-55D-SS is the standard model without a valve.
How do I mount the VFB-55D-SS?
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 VFB-55D-SS 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.
- Series:
- VF
- Product Type:
- Variable Area Flowmeter
- Media:
- Air
- Flow Range:
- 40-200 SCFH & 20-95 LPM
- Connection Type:
- Female NPT
- Connection Size:
- 1/8 in.
- Body Material:
- Acrylic
- Max Pressure:
- 150 psi
- Accuracy:
- 3% FS
- Mounting:
- Vertical
- NIST Calibration:
- Available
