Dwyer MARKIII 475 series

The Series 475-FM Mark III is housed in a durable extruded aluminum case with its solid state circuitry mounted on a tough fiberglass epoxy circuit board. To meet the most demanding applications and to provide stability of instrument reading, the 1″ w.c. range is compensated for position sensitivity through use of a unique dual sensor system. A standard 9 volt battery provides up to 100 hours of operation. Dual push pads on the front panel control on-off, auto zero, and pressure unit selection. No setup or leveling. The large 0.42″ LCD display is easy to read, minimizing data collection errors. Units include a “low battery” indicator. The pressure sensor used is a highly stable silicon piezoresistive device. Standard connections are dual sized for 1/8″ or 3/16″ I.D. vinyl or rubber tubing. Complete instructions are conveniently printed on rear of housing.

Also available is the convenient all-in-one kit (475-AV) is small, light and easy to use. No set-up or leveling needed. Included is a Pitot tube, two static pressure tips with magnetic mounting measure pressure drop across filters, condenser coils, etc. Kit comes complete with rubber tubing, 9V battery, step drill, AV calculator slide rule, and custom fitted carrying case. An indispensable test kit for the plant engineer, industrial hygienist and HVAC technician.

• Field calibration.

• Monitoring or trouble shooting HVAC systems.

• Clean room checks.

• Air velocity monitoring with Dwyer Pitot tube.

• Natural gas appliance line pressure.



• New Low Range Option 0-1.000 in. w.c.

• Measures Positive, Negative and Differential Pressures

• Rugged, Extruded Aluminum Case

• Lightweight, Fast and Easy to Use

• Selectable English/Metric Units

• FM Approved



  •  Service: Air and compatible combustible gases.
  • Wetted Materials: Consult factory.
  • Accuracy: ±0.5% F.S., 60 to 78°F (15.6 to 25.6°C); ±1.5% F.S. from 32 to 60°F and 78 to 104°F (0 to 15.6°C and 25.6 to 40°C).
  • Pressure Hysteresis: ±0.1% of full scale.
  • Pressure Limits: See Ordering page.
  • Temperature Limits: 0 to 140°F (-17.8 to 60°C).
  • Compensated Temperature Limits: 32 to 104°F (0 to 40°C).
  • Storage Temperature Limits: -4 to 176°F (-20 to 80°C).
  • Display: 0.42″ (10.6 mm) 4-digit LCD.
  • Resolution: See Ordering page.
  • Power Requirements: 9 volt alkaline battery. Battery not connected.
  • Weight: 10.8 oz. (306 g).
  • Connections: Two barbed connections for use with 1/8″ (3.18 mm) or 3/16″ (4.76 mm) I.D. tubing. Two compression fittings for use with 1/8″ (3.18 mm) I.D. x 1/4″ (6.35 mm) O.D. tubing for 475-7-FM & 475-8-FM only.
  • Agency Approvals: FM, CE.