The Shunt Gapmeter Model SGUV Mark 1 is a direct reading flowmeter for use in automatic sprinkler installations, water spray or deluge systems. It is approved for regular monitoring and testing of such systems by the LPCB, Loss Prevention
Certification Board, under their “Rules for Automatic Sprinkler Installations”, in the UK and by many equivalent organisations in other countries.

The flowmeter is a combination of two simple measuring elements. In the main flow line an orifice plate is inserted between two pipe flanges, producing a pressure drop related to flow rate. Across the orifice plate, a shunt or bypass loop uses this pressure drop to create a small flow through a similar orifice restrictor and a Variable Area flowmeter. The flow in the bypass VA meter is proportional to the main line flow, and special scaling on the glass tube allows the main line flow to be measured directly.