Model 312.20 Test Gauge Bourdon Tube Pressure Gauge with ± 0.25% Accuracy

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Applications for test gauges

  • Calibration and testing laboratories
  • Suitable for gaseous or liquid media that will not obstruct the pressure system or corrode copper alloy wetted parts

Special features of test gauges

  • High accuracy (± 0.25% of span)
  • Mirror band dial
  • Knife edge adjustable pointer
  • Pressure ranges up to 10,000 psi (700 bar)

Specifications of test gauges

Reliable, high-accuracy test pressure gauges are vital when it comes to testing and calibrating pressure. With accuracies of ± 0.25% of the span for pressures up to 10,000 psi (700 bar), the Model 312.20 Bourdon tube pressure gauge is the test gauge of choice for laboratory pressure calibration and pressure testing. It is suitable for gaseous and liquid media that do not block the pressure system or attack the copper alloy of the wetted parts.

To facilitate clear readings, it comes with a black aluminum adjustable pointer with a knife edge on a white aluminum mirrored band dial with black lettering. The Bourdon tube is either a C-shape tube made of a copper alloy or a helical 316L stainless steel tube, depending on the pressure to be measured. The 312.20 test gauge works in ambient temperatures from –40°F to +140°F (–40°C to +60°C), and media temperatures up to +180°F (+80°C). It can be lower mounted or lower-back mounted, and is protected by a 304 stainless steel case with a Buna-N vent plug and polished stainless steel bayonet ring. 

ASME B40.100 & EN 837-1

6” (160 mm)

Accuracy class
± 0.25% of span (ASME B40.100 Grade 3A)

Ranges (all ranges not stocked)
Vacuum / Compound to 200 psi (16 bar)
Pressure from 10 psi (0.6 bar) to 10,000 psi (700 bar)
or other equivalent units of pressure or vacuum

Calibration Medium
≤ 360 psi (25 bar): Gas
> 360 psi (25 bar): Liquid

Working pressure
Steady: full scale value
Fluctuating: 0.9 x full scale value
Short time: 1.3 x full scale value

Operating temperature
Ambient: -40°F to +140°F (-40°C to +60°C)

Medium: +180°F (+80°C) maximum

Temperature error
Additional error when temperature changes from reference temperature of 68°F (20°C) ±0.4% of span for every 18°F (10°K) rising or falling.

Weather protection
Weather resistant (NEMA 3 / IP 54)

Pressure connection
Material: copper alloy
Lower mount (LM) or lower back mount (LBM)
1/4” NPT or 1/2” NPT limited to wrench flat area

Bourdon tube
≤ 1,000 psi (70 bar): C-shape copper alloy
> 1,000 psi (70 bar): Helical 316L stainless steel

Copper alloy with nickel-alloy wearable parts

White aluminum with black lettering and mirrored band

Black aluminum with knife edge, adjustable

304 stainless steel with Buna-N vent plug and polished
stainless steel bayonet ring.

Laminated safety glass

Window gasket

Standard scale

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