Thermal Pressure Relief Kit for Diaphragm PumpsLincoln Thermal Pressure Relief Kit for Diaphragm Pumps Managers of vehicle service centers can now turn to our new thermal pressure relief device to protect against possible damage to their closed pipe systems caused by thermal expansion. For example, as oil warms, it expands and causes pressure sometimes oil that was 300 psi becomes 2,000 to 3,000 psi. Such pressure spikes can cause costly damage if they exceed the design capacity of pipes and