Series 475 Mark III Handheld Digital Manometer

Ranges from 1" w.c. to 150 psid, ±0.5% Accuracy

THE DWYER® SERIES 475 MARK III HANDHELD DIGITAL MANOMETER is ideal for field calibration, monitoring or trouble shooting HVAC systems, clean rooms, or a wide range of other low pressure pneumatic systems. This handy instrument measures positive, negative or differential pressures of air and natural gases in ranges from 1 in w.c. (0.249 kPa) to 150 psid (10.34 bar). Its simple operation and easy to read digital display make it an indispensable test instrument for the plant engineer, industrial hygienist and HVAC technician. When used with a Dwyer® Pitot tube, the Series 475 Mark III can also be used as an air velocity gage. See the complete 475-1-AV kit.

The Series 475 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 in w.c. range is compensated for position sensitivity through the use of a unique patented dual sensor system. A standard 9 V 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 set-up 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" ID vinyl or rubber tubing. Complete instructions are conveniently printed on rear of housing.

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

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Model Number Description Usually Ships Price Order
475-0-FM Handheld digital manometer, range 0-10.00" w.c. (2.491 kPa), max. pressure 5 psig. Same Day $184.00 Order
475-00-FM Handheld digital manometer, range 0-4.000" w.c. (0.996 kPa), max. pressure 5 psig. Same Day $184.00 Order
475-000-FM Handheld digital manometer, range 0-1.000" w.c. (.2491 kPa), max. pressure 5 psig. Same Day $248.00 Order
475-1-FM Handheld digital manometer, range 0-20.00" w.c. (4.982 kPa), max. pressure 10 psig. Same Day $184.00 Order
475-2-FM Handheld digital manometer, range 0-40.00" w.c. (9.96 kPa), max. pressure 10 psig. Same Day $142.00 Order
475-3-FM Handheld digital manometer, range 0-200.0" w.c. (49.82 kPa), max. pressure 30 psig. Same Day $142.00 Order
475-4-FM Handheld digital manometer, range 0-10.00 psi (.6895 bar), max. pressure 30 psig. Same Day $142.00 Order
475-5-FM Handheld digital manometer, range 0-20.00 psi (1.379 bar), max. pressure 60 psig. Same Day $142.00 Order
475-6-FM Handheld digital manometer, range 0-30.00 psi (2.069 bar), max. pressure 60 psig. Same Day $142.00 Order
475-7-FM Handheld digital manometer, range 0-100.0 psi (6.895 bar), max. pressure 150 psig. Same Day $142.00 Order
475-8-FM Handheld digital manometer, range 0-150.0 psi (10.34 bar), max. pressure 200 psig. Same Day $142.00 Order

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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.
See Ordering page.
Power Requirements:
9 V alkaline battery, installed non-functional, user replaceable.
10.8 oz. (306 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 475-7 & 475-8 only.
Agency Approvals:


  • 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


  • -AV Kit includes Model 475 Digital Manometer, Pitot Tube, two No. A-303 static pressure tips with magnetic mounting, 3/16" I.D. rubber tubing, No. A-397 step drill for 3/16" - 1/2" holes in 1/16" increments, No. A-532 AV slide chart, 9 volt battery, and fitted polyethylene case.


Model Number Description Usually Ships Price Code Order
166-6-CF Pocket size Pitot tube, 1/8" dia., 6" insertion length, 3" tip, with 1/8" male NPT compression fitting. Same Day $81.00 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-472 Kit, less manometer Same Day $210.00 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 475 000 AV Series 475-000-AV Mark III Handheld Digital Manometer, range 0-1.000" w.c., with air velocity kit.
SERIES 475     Mark III 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
Air Velocity Kit
NIST Certificate of Calibration

Product Literature


Catalog Pages



What's the sample rate of the 475 digital manometer series? Is there an average function of the the past samples?
The sample rate is 1 reading per second. There is no average function of past samples.
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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