The water pressure and flow test gauge assembly pictured above was a home-built unit from the early 1980s. Modern units are now readily available, inexpensive, and commonly used.
The flow-restrictor endcap pictured on the extreme left side of the unit was originally a simple flow regulator orifice plate placed into a drilled-out 3/4-in. endcap. The remaining components were stock items from a local hardware store.
The unit was originally designed and used to evaluate the adequacy of plumbing systems in correctional facilities prior to installing ware washers, washing machines, and wash-down stations. It has since become standard field equipment for the institutional sanitarian.
To use gauge assembly, the unit is attached to a standard 3/4-in. sill cock, the assembly is bled, and the assembly valve is closed to measure line pressure. After the pressure is recorded, the assembly valve is opened and flow can be measured.