Maximum difference between tested gauge and calibrated gauge?

• A. 1%
• B. 5%
• C. 10%
• D. 3%

Answer: (D)

The tested gauge must match the calibrated reference within a small tolerance to ensure readings are reliable for safety checks. The maximum allowable difference is three percent, meaning the tested gauge reading can differ from the calibrated reading by up to 3% and still be considered acceptable. This keeps pressure indications accurate enough to verify extinguisher readiness without over- or under-reading due to minor gauge variability. For example, if the calibrated gauge shows 200 psi, the tested gauge should read between 194 and 206 psi. A smaller difference, like one percent, would still be within the limit, while a larger difference, such as five or ten percent, would exceed the tolerance and indicate the gauge needs recalibration or replacement.