At what minimum frequency should the master pressure gauges used for hydrostatic testing be calibrated?

The master pressure gauges used for hydrostatic testing should be calibrated semi-annually to ensure accurate measurements. This frequency is recommended because it helps maintain the reliability and precision of the gauges, which is critical in ensuring safety during the hydrostatic testing of fire extinguishers. Accurate pressure readings are essential for determining the integrity of the extinguishers, as inaccurate measurements could lead to either an unsafe condition or an unnecessary disposal of functional equipment.

The semi-annual calibration schedule strikes a balance between operational efficiency and safety, allowing for any potential drift in gauge accuracy to be corrected without placing the equipment or personnel at risk. Calibration more frequently than this, such as quarterly, might be excessive for most applications, while annual calibration could allow for unacceptable levels of inaccuracy to develop between calibrations.