The accumulation test has advantages in that it does not require expensive vacuum chambers or vacuum pumps. It also tests for overall part leakage, unlike the sniffing method. This test method can detect leaks as small as 1 x 10-5 atm- cc/sec, depending on the size of the part and requisite cycle time.
As with the hard-vacuum method, production rates vary with the accumulation method, from 25 seconds per part to 600 parts per seven-hour shift, depending on the configuration of the system (single chamber, dual chamber, etc.). And, as with the hard- vacuum method, parts can be loaded and unloaded manually or robotically, depending upon the size and weight of the test part. Automatic tooling features are also available to facilitate connection and sealing.
For testing automotive radiators, the chamber is typically box-shaped, with a pair of gear-driven, vertically mounted, double-tooled stainless steel doors. Torque converters require a bell-type, stainless steel upper chamber.