ASTM E479-91(2006)

For any product to be tested the geometrical complexity will vary widely. However, the basic concept of determining an operative leakage specification regardless of geometries is much the same for all, whether it be simple, ordinary, or complex.

The data required for writing the OS, which is total leakage (moles), time(s), and pressure difference across the leak, are either available or can be determined by tests or measurements.

A user who selects values to be used in a leakage specification as a result of someone else having used the value or simply because of prestige reasons, may find the value or values unsatisfactory for the product.

A specification that is too restrictive may result in excessive leak testing costs. A specification that is not restrictive enough may result in premature product failure, or increased warranty costs, or both.

A typical illustration for determining a leakage specification, using the complex geometry of a refrigerant system for an example, will be used throughout this recommended guide. It is well to point out that the user should realize that the values and test methods selected do not necessarily represent the best or typical ones for this application.

1.1 This standard is intended as a guide. It enumerates factors to be considered in preparing a definitive specification for maximum permissible gas leakage of a component, device, or system. The guide relates and provides examples of data for the preparation of leak testing specifications. It is primarily applicable for use in specifying halogen leak testing methods.

1.2 Two types of specifications are described:

1.2.1 Operational specifications (OS), and

1.2.2 Testing specifications (TS):

Total, and

Each leak.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.