When replacing a gauge on the high side, the pressure graduation should be at least how many times the design pressure?

• A. 0.8 times the design pressure
• B. 1.2 times the design pressure
• C. 1.0 times the design pressure
• D. 2.0 times the design pressure

Answer: (B)

On the high-pressure side, you want a gauge that offers enough headroom above the system’s design pressure so readings stay readable and the instrument isn’t pushed to its limit by pressure spikes. The standard practice is to use a gauge with a scale at least 1.2 times the design pressure. This 20% margin lets you see pressures that may transiently exceed design and keeps the needle from pegging at the top, which helps avoid misreads and potential damage.

For example, if the design pressure is 300 psi, you’d select a gauge with a scale that goes to at least 360 psi. The other options don’t provide adequate headroom (0.8 times or 1.0 times) or go well beyond what’s needed (2.0 times), which isn’t standard practice for this requirement.