• For use with air and compatible non-combustible gases
  • Accuracy: ±0.10% of full scale (60 to 78°F)
  • Pressure Hysteresis: ±0.1% of full scale
  • Temperature Limits: 32 to 104°F
  • 4 digit LCD display
  • Connections:
    • Two barbed connections for use with 1/8 or 3/16 inch I.D. tubing for (477A-1, 477A-2, 477A-3, 477A-4 and 477A-5)
    • Two compression fittings for use with 1/8" I.D. x 1/4" O.D. tubing (477A-6 and 477A-7)
  • Adjustable damping feature for averaging fluctuating readings
  • Measure positive, negative, or differential pressures
  • Instant selection from up to nine English/metric units
  • Stores 40 readings in memory for later reference
  • Both audible and visual overpressure alarms


The Dwyer 477A Handheld Digital Manometers is packed with features needed to make pressure measurement and recording faster, easier and more accurate than ever. Containing a highly accurate differential pressure sensor that offers a 0.1% full scale accuracy on air ranges from 20" w.c. to 100 psid, the 477A allows users to instantly select from up to nine of the most widely used pressure units without having to waste time and risk mistakes with tedious conversions. A non-volatile memory function enables storage of up to 40 readings - perfect for HVAC technicians making Pitot tube traverses of air flow readings across a duct. The 477A is also ideal for maintenance personnel or technicians that require a highly accurate standard to check their instrumentation or equipment to ensure proper performance.

When working in poorly lighted areas, just switch on the 477A's handy backlight feature. The manometer automatically shuts itself off after 20 minutes to minimize battery drain. Electronic zeroing means you simply touch a single key to perfectly null out any minor pressure differences. A display HOLD key freezes the current pressure for those all-too-common situations where readings fluctuate. Included is an audible alarm to warn of overpressure plus a visual alarm warning in case ambient noise levels are too high to hear the alarm. Audible alarm also confirms a value has been stored, eliminating the need to observe display during a duct traverse.

Clear, concise operating instructions for all functions are printed on the rear of the rugged extruded aluminum case for quick reference. One-piece front membrane fully protects all keys from dust and moisture; wipes clean in seconds. Detailed written instructions, a wrist strap and 9 volt alkaline battery are included.