31 Pressure Release Test31.1 The purpose of this test is to ensure that the resettable pressure relief valve operates to prevent damage to the electric energy storage system and its electrolyte containment. This test is applicable to valve regulated technologies such as valve regulated lead acid batteries and for nickel systems with resettable relief valves.31.2 A sample of the battery/cell is to be submerged in a container of mineral oil. For large batteries only the pressure relief valve needs to be submerged.31.3 A charging current shall be caused to flow at an increased rate (to be specified by the manufacturer) until bubbles are observed to rise from the pressure relief valve.31.4 Results are acceptable if gas is released normally and the electrolyte containment system does not rupture or leak and the DUT’s casing is not ruptured