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 Pneumatic Test?

By M.J. Casey
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 pressure test verifies the pressure capacity or tests the current pressure of a system. A pneumatic test is one type of pressure test. Common pneumatic measurement test equipment includes gauges that read pressure and a source of compressed gases. Pressure testing is critical in a number of industrial areas for safety reasons and in the proper functioning of the equipment.

In pressure testing, if the fluid used to pressurize the system is liquid, usually water, the test is called a hydrostatic test. A pneumatic test implies the fluid being used is a gas, usually air or an inert gas. In determining the pressure capacity of a system, all ports to the system are closed except one through which fluid is added until either the pressure rating for the system is achieved, the pressure cannot be achieved due to leaks in the system, or the system fails catastrophically by bursting.

A pneumatic test is inherently more dangerous than a hydrostatic test due to the higher energy content of a compressed gas, and this type of test is limited to lower pressures or smaller systems. A serious injury or death may occur due to the explosions during a pneumatic test. Safety procedures for pneumatic testing are extensively documented in engineering references and code books. The American Society of Mechanical Engineers (ASME) prints the Boiler and Pressure Vessel Code (BPVC), and provides training and certification programs for engineers around the world.

A disadvantage of hydrostatic testing is the introduction of water in systems that must be water free. To test large, high-pressure systems, a low-pressure pneumatic test might be used to detect leaks followed by a high-pressure hydrostatic test at the fabricators shop prior to installation. Alternatively, methanol or other hydrocarbon liquid may be used in place of a pneumatic test. Vacuum testing is limited to low pressures as well, but it is less dangerous than pneumatic testing and is often used in laboratories to check for leaks in glassware setups.

A common example of a pneumatic pressure measurement is the use of a tire pressure gauge to measure pressure in car tires. A mechanic also measures the compression on an automobile engine by running the vehicle and measuring the pressure at each of the pistons. Cryogenic systems, such as those used in surgery, and refrigeration are often pneumatically tested as well.

To measure pressure in systems with a pneumatic test, a pressure gauge with an internal deformable diaphragm is used. The pressure is the difference between system pressure and atmospheric pressure and is often reported in pounds per square inch gauge, psig (kPa/cm2 gauge). In reactor design, wherein the operating pressure may be necessary to know from a kinetic or thermodynamic perspective, or the use of gas law calculations is required, the atmospheric pressure, 14.7 psi (101.3 kPa) must be added to the gauge pressure to get total system pressure.

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
By Telsyst — On Mar 19, 2014

There are many types of tire pressure instruments you can use. Often you can find a place to fill your tires that have a gauge built right into the pump.

In an age where everyone is trying to be eco-friendly. It is important to remember that properly inflated tires save gas.

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.