VFA-9 – Complete Datasheet Extract
(Organized by topic, English only, title-cased headings)

1. Product Identity• Model ordered: VFA-9• Series: Dwyer Visi-Float® VF Acrylic Flowmeter• Construction: 2-inch (51 mm) direct-reading precision body• Factory scale range: 20 – 200 SCFH air (standard cubic feet per hour)• Accuracy class: ±5 % of full scale (VFA specification)
2. Mechanical Specifications• Body material: clear acrylic block, white back-plate for float contrast• Float: 316 stainless steel (standard for air ranges)• O-ring: Buna-N (fluoroelastomer optional, order suffix –VIT)• Metal parts: brass standard; stainless-steel optional (order suffix –SS)• Process connection: 1/8˝ female NPT, back or end mounting inserts provided• Mounting attitude: vertical only (up-flow)• Scale length: 2˝ (50.8 mm) hot-stamped graduations• Dimensions: 4.00˝ L × 1.63˝ W × 1.19˝ H (101.6 × 41.3 × 30.2 mm)• Weight: 4.0 – 4.8 oz (0.11 – 0.14 kg)
3. Operating Limits• Maximum pressure without valve: 100 psig (6.9 bar) @ 150 °F (65 °C); 150 psig (10 bar) @ 100 °F (38 °C)• Maximum pressure with optional valve: 100 psig @ 120 °F (48 °C)• Minimum differential required: 3 psig across meter for rated accuracy• Temperature limit: 150 °F (65 °C) max (lower when valve or PTFE seat fitted)
4. Performance Data (Air @ 70 °F, 14.7 psia)• Range: 20 – 200 SCFH• Full-scale pressure drop: ≈2.5 psig (0.17 bar)• Repeatability: ≤0.25 % FS• Resolution: 2 SCFH minor division• Calibration: direct-reading; NIST-traceable certificate available (order suffix –NIST)
5. Options & Accessories (Factory-installed or Kits)• –BV: brass needle valve (inlet or outlet)• –SSV: stainless-steel needle valve• –PTFE: PTFE valve seat for corrosive gases• –PF: adjustable red pointer flag on scale• –AT: aluminum tag engraved with tag / range• –WL: without Dwyer logo (OEM)• –SPCL: oxygen / high-purity cleaning & double-bag• RKA: panel-mount brass regulator kit (maintains 3 ±0.15 psig differential, required when inlet pressure varies)• –VIT: FKM O-rings (high temp / aggressive media)
6. Installation & Mounting• Back or end 10-32 threaded metal inserts allow direct pipe support—no additional bracket required.• Use thread sealant compatible with acrylic; torque ≤0.7 N·m on 1/8˝ NPT.• Ensure verticality within ±2°; tilt causes float friction and reading error.• Protect from impact, cleaning solvents, and UV if used outdoors.
7. Maintenance & Safety• Acrylic body: clean only with mild soap solution or isopropyl alcohol; avoid ketones, aromatics, chlorinated solvents.• Float inspection: remove from line, verify free movement; replace if scratched or corroded.• O-ring replacement kit: part RK-RMB (Buna) or RK-RMV (Viton).• Pressure shock: open valves slowly; transient >200 psig may fracture body.• Not suitable for oxygen >100 psig unless –SPCL cleaned version ordered.
8. Ordering Code Construction (example)VFA-9-SSV-NIST-PTFEReads: 2˝ Visi-Float, 20-200 SCFH air, stainless valve, NIST cert, PTFE seat.
9. Typical Applications• Medical ventilators & gas blenders• Laboratory air samplers, chromatography• Air logic circuits, pneumatic controls• Cabinet purge / instrument air monitoring• Chemical injectors using carrier air
10. Compliance & Shipping• RoHS compliant (brass, SS, acrylic, Buna-N)• MSL 1 (unlimited floor life)• Standard carton: 1 unit + instruction sheet; master carton 50 pcs• Weight for export: 0.18 kg incl. packaging
11. Related Documents• DS-VF Rev.1 (Aug 2020) – complete VF series catalog• CAD outline: VF-2IN-STEP (DXF & STEP on dwyer-inst.com)• Application note AN-VF-001 “Installing Visi-Float® Meters in Pulsating Lines”