Our priming valves were designed specifically to be used in NASH vacuum pump priming systems. They are extremely simple but dependable and durable and have proven to be in successful service for nearly fifty years.
A NASH vacuum system is often used to prime one or more centrifugal pumps located above the free liquid levels of their suction sources. Vacuum draws liquid up until it fills each pump's suction line and floods its volute. This condition can be established before the pump is started up so that it is always primed and ready to begin pumping.
The priming valve is a float valve. It has an open passage from all inlet connections through to the vacuum outlet connection as long as no liquid is present. When liquid enters the priming valve body, the buoyant float rises and closes the valve.
In a typical priming system, a mixture of air, gas, and vapor continues to bubble up through the liquid into the priming valve body. It may come from inward air leakage, may be released from entrainment in liquid, or may vaporize from a volatile liquid. It separates out and accumulates in the priming valve body. As it does, the liquid level in the body goes down. the float drops, and it opens the valve to release the accumulation. With the release of air, gas, and vapor to the vacuum system, liquid rises in the body again and the valve closes.
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