What uses air pressure, or a gas such as nitrogen, as a power source traveling through copper or stainless tubes?
A) Analog signal
B) Digital signal
C) Hydraulic instruments
D) Pneumatic instruments

Question

Quizplus · Accepted Answer

A) Incorrect. The analog signal uses a continuously variable electrical current, which represents the change in variable and can be measured.
B) Incorrect. The digital signal is a series of binary numbers; it uses microprocessors (mini computers) to measure and generate an output signal.
C) Incorrect. Hydraulic instruments use pressurized liquid as the power source.
D) Correct. Pneumatic instruments are devices that use air pressure, or a gas such as nitrogen, traveling through copper or stainless tubes, as the power source for control loop instrumentation.

What Uses Air Pressure, or a Gas Such as Nitrogen