ASTM C828 1

[jpo360]

Air testing of a sanitary sewer installation under ASTM C828 calls for pressure to remain above 2.5 psig for a duration that is proportional to the length of line being tested. This seems counter-intuitive to me. If only a few pipe joints are subject to pressure in testing a shorter sewer line, why is an allowable pressure loss per joint reduced when testing a longer sewer line?

 

[SlideRuleEra]

I don't have a copy of ASTM C828, but do have a summary of it's test procedure. The test is about the volume of air lost, not the pressure. For a given diameter, say that the length of the line doubles. Both the number of joints and the volume of air in the pipe double. The test time doubles, also. Therefore, the average leakage per joint remains unchanged. For the low pressure used for the test, pressure is inversely related to volume. Pressure is measured for convenience - pressure measurement is easy, volume measurement is not.

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