When selecting a pressure transducer, or a digital pressure gauge, it is important to understand pressure types, and how they perform under different circumstances.
We have already given an overview of each pressure type, and covered absolute and sealed pressure specifically.
Today we want to highlight Compound Pressure, how it works, when to use it, and the pros and cons associated with it.
HOW IT WORKS
A sensor capable of compound pressure measurement is one that can measure both positive and negative (vacuum) pressures. The zero reference of the sensor is set at ambient pressure. The sensor is not sealed but has a vent hole that allows inherent compensation for atmospheric pressure changes.
WHEN TO USE IT
Compound pressure is used to measure both positive and negative pressure. Some examples include leak testing of pressurized lines, test chambers in labs, and general purpose low pressure measurements.
The effectiveness to measure both vacuum and positive pressure is limited to lower pressure ranges. Typically they are used for pressure measurement of 200 psi or less. If a compound pressure transducer is used for higher pressure ranges, the error band of 0.25% of full scale can exceed the vacuum range of -14.7 psi.
PROS AND CONS
Pros
Not subject to atmospheric pressure variations
Versatile solution for low pressure measurement
Cons
Poor performance in higher pressure ranges
Needs protected from moisture and dust