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How does a steam system drain under vacuum? When steam pipes, containers, and heat exchangers are filled with steam, they must be able to withstand the outward pressure generated by the steam. Therefore, steam pipeline accessories need to meet the relevant requirements for pressure pipeline components or pressure vessels. However, after the machine is shut down, the steam remaining in the pipes and containers gradually condenses; the condensed steam turns into condensate water, creating a vacuum in the pipes and containers. Vacuum can prevent condensate from being completely drained, and it also causes the pipes to be subjected to pressure from the outside acting inward due to atmospheric pressure; in severe cases, this can lead to the collapse of the container. It is therefore necessary to break the vacuum that has formed as soon as possible. The valves that Watt used to break the vacuum environment are what we call vacuum-breaking valves. It can break the vacuum caused by condensation. Under normal operating conditions, the stainless steel ball of the vacuum breaker sits on the valve seat; once a vacuum is created, the small ball moves away from the valve seat, allowing external air to enter the system and disrupt the vacuum. Sometimes a load spring is added to the vacuum break valve, which means that the vacuum can only be broken down once the internal pressure drops to a certain level, ensuring a tight seal when near vacuum conditions. The most common application of vacuum break valves is in heating and process equipment such as jacketed kettles and heat exchangers. After these devices are shut down, they still contain a certain amount of steam; when this steam condenses, a vacuum is created. This vacuum can damage the equipment, which is why it is necessary to install vacuum break valves at the steam inlets of such devices. The same situation can also occur in the steam main and inside the boiler. Vacuum breakers are also widely used in heat exchangers with temperature control, to prevent the accumulation of condensate water caused by poor drainage from the heat exchanger. By installing a vacuum breaker at the steam inlet of smaller heat exchangers from which condensate water is discharged into the atmosphere, such accumulation can be avoided. When a vacuum forms in the steam space, the vacuum breaker opens, allowing the condensate water to be discharged through the drain valve. Engineers do not want air in the steam space, as air prevents heat transfer and reduces the efficiency of the heat exchanger; this can become a problem with large heat exchangers. We recommend avoiding the use of vacuum break valves to deal with trapped condensate, or employing thermodynamic exhaust valves to remove any air that enters. If the condensate is discharged through a steam trap and then raised to a higher condensate recovery pipe, the vacuum break valve can no longer assist with the drainage; in such cases, other effective methods must be employed to remove the condensate.