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 from 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 Diffusion Pump?

By Paul Scott
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 diffusion pump is a device designed to pump gases with a high speed vapor jet as a transport medium. This process takes place as a result of the fact that gases resist diffusion in the vapor stream and are more inclined to move along with it. Diffusion pumps are characterized by very low operating pressures or, more accurately, high vacuum values which can reach 10-10 mbar. The vapor used to transport the gas is typically the product of boiling specialized oils such as silicone oil in the pump's heater section. When directed through the pump's nozzle assembly, the vapor accelerates considerably and draws the gas with it through out through the pump's discharge point.

The characteristic of gases that underpins the operation of the diffusion pump is their inclination not to diffuse or mix with a vapor stream but rather to be moved along with it. This can be clearly seen where steam exits from a window or flue. As its does so, it moves a column of air along with it, thereby causing a circulation of air in the space. Although rather modest in extent, this is a good example of the diffusion pump concept at work. The main difference between the workings of the pump and the chilly breeze in the bathroom, however, is the velocity at which the vapor moves. For a diffusion pump to reach its full potential, the vapor used as a transport medium is accelerated to extremely high speeds.

Diffusion pumps are very simple devices with no moving parts; this makes them particularly long lived and easy to maintain. The main sections on a typical example consists of a heater section where the vapor is produced, a pumped gas inlet, a series of nozzles, and an outlet. Secondary elements consist of cooling coils and oil return ducts. The vapor material is heated to the boiling point in the heater section with the resultant vapor being directed into the nozzle section. There the vapor accelerates before passing the pumped gas inlet where it draws the gas into the outlet channel.

In the outlet channel, the vapor is cooled and recondenses to a liquid. The accelerated gas then exits the pump's inner section where it returns to atmospheric pressure and is discharged. The recondensed oil then flows back to the heater section. The vapor materials in a diffusion pump are typically silicone based oils, although mercury is often used in sensitive laboratory applications where oil contamination is undesirable.

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.