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Some of the more frequently asked questions to our applications department revolve around air pressure regulator exhaust, bleed, leakage and air consumption. It is important to first consider the different paths that gas will take to escape from a regulator. Then we can understand the differences between regulator exhaust, designed-in bleed, simple leakage and total air consumption. There are typically three ways that air (or any media being regulated) will escape the closed regulator system; over-pressurization relief or exhaust, designed in bleed and unintended leakage.
Exhaust is the normal relief to atmosphere of downstream pressure when it increases above the set point of a regulator or a regulator is adjusted downward. There will be no exhaust if a “non-relieving” regulator is used. To prevent downstream pressure buildup when using a non-relieving regulator there should be constant flow downstream or some form of downstream relief should be utilized. If required, exhaust can be captured and vented to an appropriate location.
Bleed is a term that is used for intentional leakage generated by some precision regulators. Many precision regulators allow for a small amount of airflow to improve accuracy, sensitivity and repeatability. This air consumption usually makes it way to atmosphere via an orifice out the side of the regulator or sometimes through the exhaust port.
Leakage is a term that is used to describe air that may escape past relief seats and through external seals. Ideally, this would be zero, but manufacturing tolerances, imperfect seals, variability of elastomer compression and price point considerations require us to accept that sometimes there will be a minimal amount of leakage. There are few options that can help improve these concerns. Tapped exhaust ports can be used to capture any leakage by the relief seat. Special “soft” relief seats can be used to make a better seal. There is also the option to create a “bubble tight” regulator with special sealing materials and processes.
So what type of regulator is right for your application? See our other blog about application considerations. Just because precision regulators may consume a small amount of air in a steady-state condition, it may not disqualify it for use in an inert or other exotic gas application. Some precision regulators consume less gas than others and there are standard and custom options that can be used to decrease all forms of leakage and consumption. Please contact us for help with your next regulator application.