According to IS 2190 guidelines (adopted under the Maharashtra Fire Prevention and Life Safety Measures Act), fire extinguishers must be serviced and inspected annually, and refilled immediately after any discharge, even if it was only partially used.
For dry powder (ABC/BC) and water-based cylinders, a complete refilling and interior cleaning is mandatory every 5 years, along with a hydrostatic pressure test (HRT) at 30-35 kg/cm². For CO2 and clean-agent extinguishers, the hydrostatic testing cycle is every 3 years. Keeping detailed logbooks with service tags attached to each cylinder is legally required during building inspections.
In our mall, the fire officer checks the pressure gauges every month. If the needle drops below the green zone, we get them refilled immediately. Don't wait for the annual check if pressure drops!