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Choosing a Gauge: Temperature Effects

If you work outdoors, your readings may be less accurate than you think. Temperature should not affect your pressure gauge. Any specification that indicates a narrow operating temperature band, for example “from 18 to 28°C”, implies this gauge has inadequate temperature compensation. Some gauges may not even include a narrow temperature band at all. What looks like small accuracy adder for every increment of temperature rapidly overwhelms the basic specification of the gauge at the temperatures they work in every day.

For example: Let’s compare our 30 Series Calibrator with a real life “Brand A” gauge.

Accuracy Statement – with temperature compensation details:

30 Series: ± (0.05% of reading) + (0.005% FS) – Fully temperature compensated
Brand A: ± (0.025% FS) + (0.015% of reading) – No compensation. Temperature effects are ± 0.002% of reading per °F outside of 68°F.

Taking the temperature effect out, Brand A would appear to have a higher accuracy than the 30 Series. But, once the temperature effects are added in, they overwhelm Brand A’s basic accuracy.

 To calculate the temperature effect at 5000 psi and 100°F:

• Measurements occur 32° outside of Brand A’s 68°F point (100 – 68 = 32)
• Temperature Effect: 32 x ± (0.002% of 5000 psi) = 3.2 psi
Comparing two 5000.0 psi gauges at 100 degree Fahrenheit

For outdoor use, pressure gauges need active temperature compensation.