5.1 The types of rope rescue systems to which this test method apply use a tensioned mainline and untensioned belay line. If a fall occurs because of a mainline system failure or misuse, considerable energy must be absorbed by the belay for a successful arrest. This drop test method simulates a “worst case” condition when systems are operated as designed, and is designed to help evaluate and compare the performance of various rope rescue belay systems under such conditions. (See Note 1.) The successful catching of a load does not imply that the tested system is suitable for any and all belaying. See X1.2.

Note 1: Higher forces may be encountered under some circumstances, such as the belay being operated with excessive slack.

1.1 This test method covers drop test procedures to measure rope rescue belay system performance. It applies only to belay systems consisting of an untensioned rope connecting the load to an anchored belay device. This test method does not address other types of belays, such as self-belays or belays for lead climbing, nor does it test the rescuer's belaying ability.

1.2 This test method may be used to help measure a rescue belay system's performance under controlled drop test conditions, but it will not necessarily provide guidance as to which belay method is most suited to a particular application. Other considerations, such as ease of handling, performance on different types and diameters of rope, portability, versatility, system safety factor, cost, and automatic operation that do not require the positive action of the belayer may influence the selection of a belay system and are not dealt with in this test method. See X1.1.

1.3 The values stated in SI units are to be regarded as standard.

1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Additional precautions for this test method are given in 8.1 and 8.2.