Overview
The Dwyer 475-000 Mark III digital manometer is a handheld instrument designed for field measurement of pressure in HVAC, pneumatics, and gas utility applications. This device measures positive, negative or differential pressures of air and natural gases in ranges from 0 to 1″ w.c. with a metric range of 0.249 kPa. The device is FM-approved intrinsically safe for Class 1, Div. 1, Group A, B, C, D, T4 hazardous locations. The unit features a four-digit liquid crystal display and simple dual-button operation for zero-setup field deployment.
Key Features
- Large, easy to read LCD display
- Rugged aluminum case protects instrument from damage during transport and use
- Selectable pressure units: inches of water column (WC), psi, kPa
- Dual push pads control on/off, auto zero, and pressure unit selection for simple operation with no setup needed
- When used with a Dwyer Pitot tube, can also be used as an air velocity gauge
- Maximum pressure: 5 psig
Technical Specifications
Pressure Range: 0–1.000″ w.c. (0.2491 kPa)
Maximum Pressure: 5 psig
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
Connections: Two barbed connections for 1/8″ (3.18 mm) or 3/16″ (4.76 mm) I.D. tubing, and two compression fittings for 1/8″ (3.18 mm) I.D. x 1/4″ (6.35 mm) O.D.
Display: Four-digit liquid crystal display
Hazardous Location Approval: FM approved for Class 1, Div 2, Groups A, B, C, D, T4 Ta = 70°C
Included Accessories: User manual, 9V battery, rugged aluminum carrying case
Typical Applications
- Monitoring natural gas pressures on boilers and other combustion equipment
- Monitoring or troubleshooting HVAC systems
- Air velocity monitoring when used with a Dwyer Pitot tube and AV calculator
- Field calibration of other instruments
- Clean room pressure differential inspection
Compatibility & Replacements
Compatible With
- Dwyer Pitot tube (for air velocity measurement)
- Standard 1/8″ and 3/16″ I.D. pneumatic tubing
- HVAC system test ports and pressure taps
- Natural gas appliance service connections
- 9V standard battery power
Replaces / Drop-In Replacement For
- Dwyer 475-000 (non-FM approved version, if applicable)
- Earlier Dwyer manometer models in low-pressure applications (0–1″ w.c. range)
Works With
- Dwyer Pitot tubes for air velocity calculations
- Dwyer AV calculator software (for velocity measurements)
- Industry-standard low-pressure gauges and pressure monitoring systems
- Pneumatic control systems and HVAC test equipment
