Test pressure gauges must be capable of being read within what percentage of the test pressure?

Test pressure gauges used in conjunction with portable fire extinguishers must be able to accurately indicate the test pressure within a tolerance of 1%. This level of accuracy is critical to ensure that the gauge provides a reliable reading during testing, ensuring safety and compliance with the standards set out in NFPA 10. A tolerance of 1% means that if the test pressure is set at a specific value, the gauge should read within 1% of that value, affirming the integrity and effectiveness of the extinguisher under test conditions. This precision is essential to prevent underestimating or overestimating the pressure, which could lead to either an insufficient or excessive performance of the fire extinguisher, compromising safety standards.