Series 477 Handheld Digital Manometer

Selectable Pressure Units, ±0.5% Accuracy, FM Approved Intrinsically Safe for Hazardous Locations, Class 1, Div. 1, Group A, B, C, D, T4

Series 477 Handheld Digital Manometers are packed with features you need to make low pressure measurement and recording faster, easier and more accurate than ever. First, you can instantly select from up to nine of the most widely used pressure units without having to waste time and risk mistakes with tedious conversions. Next, a non-volatile memory function enables storage of up to 40 readings - perfect for HVAC technicians making Pitot tube traverses of airflow readings across a duct. The Series 477 is FM approved intrinsically safe for hazardous locations, Class 1, Div. 1, Group A, B, C, D, T4.

When working in poorly lighted areas, just switch on the handy backlight feature. It 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. We even included an audible alarm to warn you of overpressure plus a visual alarm also confirms a value has been stored, eliminating the need to observe display during a duct traverse.

Product Applications

  • Field calibration.
  • Monitoring or trouble shooting HVAC systems.
  • Clean room checks.
  • Air velocity monitoring with Dwyer Pitot tube.
  • Natural gas appliance line pressure.

Models & Ordering

Build Your Custom Part. Use our Product Configurator

Model Number Description Usually Ships Price Order
477-0-FM Handheld digital manometer, range 0-10.00" w.c., max. pressure 5 psig. 1-2 Weeks $342.00 Order
477-00-FM Handheld digital manometer, range 0-4.000" w.c., max. pressure 5 psig. 1-2 Weeks $342.00 Order
477-000-FM Handheld digital manometer, range 0-1.000" w.c., max. pressure 5 psig. 1-2 Weeks $364.00 Order
477-1-FM Handheld digital manometer, range 0-20.00" w.c., max. pressure 10 psig. Same Day $342.00 Order
477-2-FM Handheld digital manometer, range 0-40.00" w.c., max. pressure 10 psig. Same Day $284.00 Order
477-3-FM Handheld digital manometer, range 0-200.0" w.c., max. pressure 30 psig. Same Day $284.00 Order
477-4-FM Handheld digital manometer, range 0-10.00 psi, max. pressure 30 psig. Same Day $284.00 Order
477-5-FM Handheld digital manometer, range 0-20.00 psi, max. pressure 60 psig. Same Day $284.00 Order
477-6-FM Handheld digital manometer, range 0-30.00 psi, max. pressure 60 psig. Same Day $284.00 Order
477-7-FM Handheld digital manometer, range 0-100.0 psi, max. pressure 150 psig. Same Day $284.00 Order
477-8-FM Handheld digital manometer, range 0-150.0 psi, max. pressure 200 psig. Same Day $284.00 Order

Can't find what you need? Try our Product Configurator


Air and compatible gases. FM models: air and compatible combustible gases.
Wetted Materials:
Consult Factory.
±0.5% Full Scale, 60 to 78°F (15.6 to 25.6°C); ±1.5% Full Scale 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 Catalog 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).
0.42" (10.6 mm) 4-digit LCD.
Response Time:
1 second.
See catalog page.
Power Requirements:
9 V alkaline battery, installed non-functional, user replaceable.
10.2 oz (289 g).
Process 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 477-7-FM & 477-8-FM only.
Agency Approvals:


  • New Low Pressure Ranges.
  • Instant Selection from up to Nine English/Metric Units.
  • Stores 40 Readings in Memory for Later Reference.
  • Measures Positive, Negative or Differential Pressures.
  • Large Easy-to-Read 0.4" LCD Display Includes Switchable Backlight for Great Visibility - Anywhere!
  • Both Audible and Visual Overpressure Alarms.
  • Includes + and - Indicators plus Low Battery Warning.
  • Operates up to 100 Hours on a Single 9 Volt Battery.


Model Number Description Usually Ships Price Code Order
166T Telescoping Pitot tube. Same Day $180.00 Order
A-201 Rubber latex tubing has less tendency to kink in storage and occupies less space, thus is best for portable work. 3/16" ID, 9' length. Same Day $7.50 N Order
A-303 Portable static pressure tip, for 3/16" ID rubber or plastic tubing with 4" insertion. Same Day $9.95 Order
A-375 Compression fitting connections, 1/8" tube to 1/8" NPT male. 1-2 Weeks $3.30 Order
A-397 Rugged step drill, quickly provides true round holes in thin materials, no center punch needed to start, automatically de-burrs drilled hole, high speed steel, drills 3/16" through 1/2" holes in 1/16" increments. Same Day $33.75 N Order
A-402A Nylon carrying pouch for various digital manometers - 7-1/2" x 3" x 2-1/4". Same Day $41.75 Order
A-463 Plastic carrying case with foam liner for 475-1-AV air velocity kit - 13-1/2" x 10" x 2-3/8". 1-2 Weeks $74.00 Order
A-472T Telescoping pitot tube air velocity kit less manometer. 1-2 Weeks $325.00 Order
A-532 Air velocity calculator slide chart. Same Day $10.00 Order
UHH-C1 Soft carrying case Same Day $39.00 Order

Model Chart

EXAMPLE 477 000 FM AV Series 477-000-FM-AV Handheld Digital Manometer, range 0-1.000" w.c., FM approved, with air velocity kit.
SERIES 477       Handheld Digital Manometer
(If ordering -AV
Option, these ranges
will include a Model
166-6-CF Pitot Tube
in the Air Velocity Kit.)
    1.000" w.c. / .2491 kPa
4.000" w.c. / 0.996 kPa
10.00" w.c. / 2.491 kPa
20.00" w.c. / 4.982 kPa
40.00" w.c. / 9.96 kPa
200.0" w.c. / 49.82 kPa
10.00 psi / .6895 bar
20.00 psi / 1.379 bar
30.00 psi / 2.069 bar
100.0 psi / 6.895 bar (range not available with -AV Option)
150.0 psi / 10.34 bar (range not available with -AV Option)
(You must order -AV
Option with these ranges
and will include a Model
166T Telescoping Pitot
Tube in the Air Velocity Kit.)
    1.000" w.c. / .2491 kPa with Telescoping Pitot Tube
4.000" w.c. / 0.996 kPa with Telescoping Pitot Tube
10.00" w.c. / 2.491 kPa with Telescoping Pitot Tube
20.00" w.c. / 4.982 kPa with Telescoping Pitot Tube
40.00" w.c. / 9.96 kPa with Telescoping Pitot Tube
200.0" w.c. / 49.82 kPa with Telescoping Pitot Tube
10.00 psi / .6895 bar with Telescoping Pitot Tube
20.00 psi / 1.379 bar with Telescoping Pitot Tube
30.00 psi / 2.069 bar with Telescoping Pitot Tube
TYPE     FM   FM Approved Unit
Air Velocity Kit
NIST Certificate of Calibration

Product Literature


Catalog Pages




We use series 475-6-FM Mk III digital manometer. What is the recommended calibration interval?
We do not have an official recommended calibration interval. However, we would suggest checking the calibration at least once or twice a year depending on the applciation and how often the unit is used.
Is there a manometer that is compatible with chlorine gas and sodium hydroxide (bleach)?
Unfortunately, we do not have any manometers available that can handle chlorine gas or sodium hydroxide (bleach).

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