旁通孔用于在各种情况下降低流体流动中的压力，特别是在无法获得可变流量的情况下。与文丘里管、方边孔板和类似装置的研究相比，对于类似于管嘴或管嘴孔板的孔板的性能知之甚少。因此，在大多数情况下，系统设计师根据假设的损失选择乳头孔，其流量系数约为0.6。然而，在这种情况下，重要的是要有额外的信息，以优化设计这些系统的最低能耗。在此，给出了压力降作为1/8至7/8英寸范围内螺纹接头孔的流量函数的数据和设计信息。 （3.2至22.2 mm）的管道直径，范围为标称1/2至1 1/2英寸。（12.7至38.1毫米）直径。对于大于20 gpm（4.54 m3/h）的流量，给定数据的曲线拟合精度在正负25%范围内，对于较低的流量，曲线拟合精度高达正负40%。流量系数也是雷诺数的函数。结果表明，作为雷诺数的函数，数据中似乎没有明显的趋势。然而，将雷诺数乘以直径比和孔口直径的系数，会产生一种趋势，可用于乳头-孔口系统的设计。流量系数可以很好地预测，本文研究的所有孔板线尺寸的一般误差为正负5%（置信度为77%）。 本文给出的结果可用于开发具有其他误差和置信水平的流量系数预测。对于未来的工作，需要更多关于大孔口组合的数据。然后需要进行理论研究，以了解通过直径比和/或孔口和管线直径的函数修改压降和/或雷诺数的基础。这项工作和未来的工作将能够提供基本数据，以开发建模和软件工具，从而选择最佳孔口，以最大限度地减少能源浪费。此外，未来的工作重点应放在变速泵系统设计（不需要螺纹接头孔等限流器）与恒速泵系统设计（带有某种类型的限流器）的比较上。 引用:德克萨斯州达拉斯ASHRAE Transactions第119卷第1部分。

Bypass orifices are used to reduce pressure in fluid flow for a variety of situations, specifically wherein variable flow rates are not available. As compared to studies regarding venturis, square-edged orifices, and similar devices, much less is known about performance of orifices configured similar to pipe nipples or nipple orifices. Thus, in most cases, the system designer chooses a nipple orifice based on assumed losses, which has a discharge coefficient of about 0.6. However, it is important in such situations to have additional information in order to optimally design these systems for minimum energy consumption.Herein, data and design information are presented for pressure drop as a function of flow rate for nipple orifices ranging from 1/8 to 7/8 in. (3.2 to 22.2 mm) diameter in pipes ranging from nominal 1/2 to 1 1/2 in. (12.7 to 38.1 mm) diameter. Curve fits accuracies for the data given are within plus or minus25% for flow rates above 20 gpm (4.54 m3/h), and range as high as plus or minus 40% for lower flow rates.Discharge coefficients are also presented as a function of Reynolds Number. It is shown that there appears to be no clear trend in the data as a function of Reynolds Number. However, multiplying Reynolds Number by factors of diameter ratio and orifice diameter yields a trend that could be used in nipple orifice system design. Discharge coefficients can be predicted reasonably well, with the general error for all orifice-line sizes studied herein being plus or minus 5% (with 77% confidence). The results presented herein can be used to develop discharge coefficient predictions with other errors and confidence levels. For future work, more data are needed on large orificeline combinations. Needed then are theoretical studies to understand the basis for modifying pressure drop and/or Reynolds Number by functions of diameter ratio and/or orifice and line diameters. This and future work will then be able to provide basic data to develop modeling and software tools to allow the optimum orifice to be selected to minimize energy waste. In addition, future effort should be focused on the comparison of variable speed pump system design, that does not need flow restrictors like nipple orifices, with constant speed pump system design with some type of flow restrictor.