当他们从配水干管安装支管时，水务公司的管理人员经常争论使用水龙头的好处，而不是关闭管线安装T形管件。部分讨论围绕着一个事实展开，即一个丝锥，尤其是一个尺寸对尺寸的丝锥，其孔口尺寸将小于T形管件。令人担忧的是，这将导致额外的水头损失和容量降低。在低流量条件下，这种容量损失可以忽略不计，但在火灾流量期间，这种损失可能会变得显著。 本文报告的实验结果表明，只要孔口（分接头）大于管道尺寸的90%，分配系统中的承载能力损失并不显著。

When they install a branch from a water distribution main, water utility managers often debate the benefits of using a tap as opposed to shutting down the line to install a T-fitting. Part of the discussion centers around the fact that a tap, especially a size-on-size tap, will have a smaller orifice size than will a T-fitting. The concern is that this will lead to additional head loss and decreased capacity. For low-flow conditions, this loss in capacity is negligible, but during fire flows, this loss can become significant. This article reports the results of experiments that indicate the loss of carrying capacity in distribution systems is not significant as long as the orifice (tap cutout) is greater than 90% of the pipe size.