Torsion spring checks shall have reversible elastomer discs and in operation produce drip tight closure against reverse flow caused by backpressure or backsiphonage.

• 扭力弹簧止回阀应该配置双向合成橡胶阀瓣，并且在工作时对于反压力和反虹吸所产生的回流具有防滴漏关闭性能。