Vacuum breaker
A vacuum breaker opens an air-inlet path when internal pressure falls below the surrounding pressure, interrupting an unwanted vacuum and closing again as pressure recovers. Steam condensation after shutdown can create this condition, while liquid systems may need air admission during draining or negative-pressure events. This duty differs from pressure reduction, overpressure relief, and continuous air release under operating pressure. Selection should evaluate the vacuum scenario, required air-admission capacity, medium, installation point, condensate drainage, and spring-loaded or non-spring construction.
Application and duty
Controlled air admission to protect equipment or piping against vacuum caused by condensation, draining, or pressure loss; capacity and location must match the scenario.