ASTM WK24716

    New Specification for Safe Design and Installation of Suction-Limiting Gravity Systems for Suction Entrapment Prevention in Swimming Pools, Spas, Hot Tubs, and Wading Pools

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    Developed by Subcommittee: F15.51 | Committee F15 | Contact Staff Manager


    1. Scope

    1.1 This performance specification provides requirements for safety in design and installation when using a suction-limiting gravity system for suction entrapment prevention in swimming pools, spas, hot tubs, or wading pools. Gravity collector tanks work on the physical principle of providing a vented reservoir in the piping between the suction outlet and the pump. During normal operation the water level in the vented reservoir is lower than the pool, so water flows from the pool to the reservoir, which is drawn by the pump. Since the physical pump suction piping elevation at the collector vessel controls the lowest possible level in the reservoir, the maximum differential pressure at a bather-blocked suction outlet is the difference in elevation between the pool and the reservoir. 1.2 The purpose of a collector vessel or safety gravity system is to relieve the vacuum at the suction outlet(s) caused by any blockage of the suction outlet(s). It is intended to prevent body entrapment at the suction outlet(s) and may also mitigate limb entrapment. It is not intended to prevent other injuries caused by the suction outlet(s) such as hair entrapment, mechanical entrapment, or evisceration. 1.3 The values given in inch-pound units are to be regarded as the standard. The values in parentheses are for information only. 1.4 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 to determine the applicability of regulatory limitations prior to use.


    entrapment; hot tub; safety gravity system; spa; swimming pool; collector vessel

    The title and scope are in draft form and are under development within this ASTM Committee.

    Citing ASTM Standards
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    Work Item Status

    Date Initiated:

    Technical Contact:
    David Stingl

    Draft Under Development