We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Relief Valve?

By Lori Kilchermann
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A relief valve is a device used to bleed off excess pressure in a pneumatic or steam line. Typically constructed with adjustable tension springs, the relief valve has a panel or valve that will open as the pressure reaches a predetermined point. It is often referred to as a blow-off or pop-off valve due to the sound the escaping pressure makes as the relief valve is pushed open. The typical relief valve is adjustable as well as rebuildable to allow the valve to work in a vast assortment of manufacturing operations. While the common relief valve will reset itself after venting excess pressure, which allows the system to remain functional, some emergency pop-off valves must be manually reset after opening.

With machines such as air compressors, excess air pressure inside of the holding tank can lead to dangerous explosions and injury or death to nearby operators. While the typical air compressor is constructed with a pressure-sensitive safety switch intended to turn the compressor on and off as the air pressure builds, it can occasionally fail. When this happens, the compressor could potentially build up enough air pressure to cause the tank to rupture. By installing a relief valve in the compressor's tank, the valve can open and exhaust any excess pressure prior to the tank failing and potentially injuring persons and property.

Many pneumatic presses and other types of manufacturing machinery depend on a relief valve to bleed off excess pressure as the machine performs its usual task. When a pneumatic press is operated, a loud swoosh of air can be heard escaping the press after ever pressing cycle. This is the sound of the blow-off valve releasing the high air pressure required for the press to accomplish its task. The press regains the high pressure needed to operate as the press is being loaded by the press operators. Once loaded and ready, the press cycles through another pressing sequence and once again exhausts the air pressure and returns to the starting position.

With steam-operated machinery, the process is much the same. A relief valve vents the built-up steam from the lines or the machinery after each duty cycle and avoids over-pressurizing the components within the machine. The sound of the steam being released is often very noisy and sharp as the valve opens and closes at a high rate of speed, allowing the steam pressure to escape instantly with no gradual seepage of pressure. The closing of the valve is just as abrupt and often makes a louder sound than an opening valve as the pressure escaping through the relief valve is capped off almost instantly.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.