The HBE Anti-Flash valve Model AFV is provided specifically to eliminate damage to the automatic recirculation valve and bypass piping from flashing and cavitation.

How it Works

The Anti-Flash valve functions as a variable orifice to assure the pressure of the downstream liquid does not fall below the vapor pressure after exiting the automatic recirculation valve.


Applications which require Anti-Flash valves include boiler feed, condensate, and certain process fluids which bypass back to a low or negative pressure vessel.  Another need for these valves occurs on boiler feed pumps returning to the deaerator in peaking units.  Automatic recirculation valves can run in a modulating state for extended periods of time with the bypass partially open.  During these periods of low bypass flow the amount of backpressure normally available from piping friction is decreased.  The temperature rise across the pump and valve can result in a flashing/cavitation condition.  The variable orifice in the valve adjusts to provide the needed back pressure during these lower flow conditions and assures a flashing/cavitation condition does not occur.


This valve is a wafer style design and is installed between flanges of the bypass piping with the same size and ASME pressure class rating.  Installation location of the valve can be close to the outlet of the automatic recirculation valve bypass but is not required.  When installed adjacent to the return vessel the  valve will assure protection of the entire bypass system.


No external power is used for operation of the Anti-Flash valve.  The wafer style body design makes installation simple.  Functioning as a variable orifice makes the valve very effective over a much wider flow range than an orifice plate.  Precision machined internals make operation of the valve smooth and reliable.

Anti-Flash Valve

Bypass line protection with HBE Engineering series AFV anti-flash valve.