1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays.

1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported.

1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice.

1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls.

1.5 The categories of solar collector cover plate materials to which this practice may be applied cover the range of:

1.5.1 Brittle sheet, such as glass,

1.5.2 Semirigid sheet, such as plastic, and

1.5.3 Flexible membrane, such as plastic film.

1.6 Solar collector cover materials should be tested as:

1.6.1 Part of an assembled collector (Type 1 specimen), or

1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen).

1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.8 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.