This test is intended to assess the extent to which collectors are substantially resistant to rain penetration. The collectors must not normally permit the entry of either free-falling rain or driving rain, either through the glazing seals or from ventilation holes or drain holes. For this test, the inlet and outlet fluid pipes of the collector must be sealed, and they must be placed in a test rig at the shallowest angle to the horizontal recommended by the manufacturer. If this angle is not specified, then the collector can be placed at a tilt of 45° to the horizontal or less. Collectors designed to be integrated into a roof structure must be mounted on a simulated roof and have their underside protected. Other collectors must be mounted in a conventional manner on an open frame. The collector must be sprayed on all sides using spray nozzles or showers for a test period of 4 h.
For collectors that can be weighed, weighing must be done before and after the test. After the test, external surfaces of the collector must be wiped dry before the weighing. During the wiping, transport, and placement on the weighing machine, the angle of inclination of the collector must not be changed appreciably. For collectors that cannot be weighed, the penetration of water into the collector can be determined only by visual inspection.