Traditionally, with evaporators we have used three different types of ‘pressure’ performance tests, at Dana-Thermal Products. A proof test (2.35 MPa / 340 PSI) and low & high pressure sinusoidal cycle tests, where none of the test specimens are run to failure. Unfortunately, little evidence is available to indicate the suitability of a sinusoidal cycle to simulate hot soak conditions. These tests, not having been run to failure, provide little information in analyzing potential field failure modes.
A new, trapezoidal shaped, run to failure pressure cycle test has been developed (TPC), to better represent conditions seen in the field. This profile more closely resembles the hot soak phenomena where the pressure rises, with under-hood temperature, holds for a length of time and then drops off as the system cools. Testing, to date, has linked the new test failure modes to those seen in field failures. It has been used to aide in the development of a new proof test specification, since it is now possible to determine what, if any, ‘damage’ higher pressure / longer proof tests have inflicted on the component.
The development of this test / specification along with its use and future applications will be presented.
