Excess Flow Valves

Excess flow valves are valves that automatically close due to a high fluid flow condition.  They are sometimes referred to or branded as a flow fuse, due the analogy with an electrical fuse stopping the flow of electricity due to a high current condition. Once the valve is “tripped” the flow is blocked completely and the valve is held in the closed position by the upstream pressure until it is equalised or nearly equalised with the downstream pressure.

Some of our larger excess flow valves are equipped with manual bypass valves which allow pressure equalisation without depressurising the upstream system. Providing instant shut off in the event of a hose break or line failure, our excess flow valves can be disassembled for repair or inspection without removal from pipeline. They are field adjustable with a broad adjustable range, meet OH&S requirements for safety shutoff valves and operate effectively with liquids or gases and are suitable for in-line flow.

PAC have a longstanding productive relationship with GVS / Malema. Malema are a trusted and known brand worldwide for their high quality flow switches. The excess flow valve is a larger version of the instrumentation flow switch. These valves provide a high quality reliable fail safe on hazardous systems in the event of system failure. The GVS / Malema product offers a high level of accuracy (+/-10% maximum) and a high level of repeatability (+/- 2%).

These valves also offer a reset mechanism which eliminates the need for additional piping and hardware upstream along with reducing the overall cost of installation. This manual reset mechanism utilizes a built-in reset valve on a bypass line which allows the user to equalize the pressure on each side of the valve which allows the excess flow valve to reset.

In critical safety environments quality, reliability and accuracy are vital to ensure that in the event of failure the surrounding environment and pipework is kept safe. PAC are able to offer solutions of the highest quality to suit your critical applications.

Excess flow valve suppliers


Carbon steel, stainless steel, exotic alloys


ANSI 150 to 2500

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