Thermal Pressure Relief Device for Diaphragm PumpsLincoln Thermal Pressure Relief Device 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. Lincoln Thermal Pressure Relief Device 282876 Lincoln Thermal Pressure Relief Device 282876