Thermal flow meter VA 520

massvolumefor compressed air

Product information
The VA 520 is an inline thermal mass flow meter for compressed air and non-corrosive gases. Threaded variants allow installation and removal under pressure. The integrated measuring section can stay in the line for cleaning or recalibration and be sealed with a cap.

Available items (measuring section / Order No.)

• VA 520 flow meter, 1/2" measuring section — 0695 1521
• VA 520 flow meter, 3/4" measuring section — 0695 1522
• VA 520 flow meter, 1" measuring section — 0695 1523
• VA 520 flow meter, 1 1/2" measuring section — 0695 1524
• VA 520 flow meter, 2" measuring section — 0695 1525
• Flanged versions (examples): DN25 — 0695 2523; DN50 — 0695 2525; DN65 — 0695 2527; DN80 — 0695 2528

Flow measuring ranges (examples for compressed air, reference conditions DIN 1945 / ISO 1217: 20 °C, 1000 mbar)

• 1/2" (R 1/2"): Low-Speed (50 m/s): 20 l/min (14 cfm); Standard (92.7 m/s): 45 l/min (25 cfm); Max (185 m/s): 90 l/min (50 cfm); High-Speed (224 m/s): 110 l/min (60 cfm)
• 3/4" (R 3/4"): Low-Speed: 45 l/min (25 cfm); Standard: 85 l/min (50 cfm); Max: 175 l/min (100 cfm); High-Speed: 215 l/min (125 cfm)
• 1" (R 1"): Low-Speed: 75 l/min (45 cfm); Standard: 145 l/min (85 cfm); Max: 290 l/min (170 cfm); High-Speed: 355 l/min (210 cfm)
• 1 1/2": Standard examples: 195 l/min (115 cfm) — Max: 730 l/min (430 cfm) — High-Speed: 1450 l/min (850 cfm)
• 2": Standard examples: 320 l/min (190 cfm) — Max: 1195 l/min (700 cfm) — High-Speed: 1450 l/min (850 cfm)

Advantages of the VA 520

• Mass flow measurement with direct standard volume flow output
• High accuracy across small and large flows (suitable for leak detection)
• Pressure and temperature compensated by thermal mass flow principle
• Easy installation/removal under pressure; measuring section can remain in line and be sealed for cleaning or recalibration
• No moving parts → low maintenance
• Very low pressure loss due to minimal internal blockage
• Suitable for compressed air and non-corrosive gases (air, N2, O2, Ar, He, CO2); gas type selectable via service software or data logger

Notes on installation / mechanical data
For flange and integrated versions a shortened inlet section may apply. Observe recommended minimum inlet length on site where indicated (recommended length = 15 × inner diameter).

Interfaces and outputs

• Digital: RS-485 (Modbus-RTU); optional Ethernet (PoE), M‑Bus
• Analog: 4…20 mA for m3/h or l/min
• Pulse: 1 pulse per m3 or per litre, galvanically isolated; pulse weight adjustable; pulse output can be used as alarm relay

Technical specifications

• Model: VA 520 (inline, threaded)
• Sensor: Thermal mass flow sensor
• Measured media: Compressed air and non-corrosive gases
• Units (selectable): m3/h, m3/min, l/min, l/s, ft/min, cfm, m/s, kg/h, kg/min, g/s, lb/min, lb/h
• Measuring ranges: see section-specific tables (1/2" to 2" and flanged/DN versions). Max speed versions up to 185 m/s (High-Speed up to 224 m/s)
• Accuracy: ±1.5% of measured value ±0.3% of full scale (on request ±1% of m.v. ±0.3% f.s.)
• Operating temperature: -30 … 80 °C
• Operating pressure: -1 … 16 bar (optionally up to PN 40)
• Supply: 18…36 VDC, 5 W
• Analog load: < 500 Ω
• Housing: Polycarbonate, IP65
• Measuring section material: Stainless steel (1.4301 or 1.4571)
• Process connection (thread versions): R 1/4" to R 2" (BSP) or 1/2" to 2" NPT
• Mounting position: any
• Weight (indicative): approx. 3.5 kg
• Order reference example (threaded 1/2"): 0695 1521