5 Tips to Keep Your Diffusion Pumps Running Smoothly

By Gene Ligman
dij family hero image

With its powerful vacuum range and fast pumping speeds, the oil diffusion pump is a popular and reliable vacuum pump for many industrial and scientific applications.

Unlike some vacuum pumps, diffusion pumps contain no rotating parts. This means you don’t have to worry about problems with mechanical wear or failure. Diffusion pumps generally require minimal maintenance too.

You can reduce downtime and extend the life of your diffusion pump even further by following good practices in your day-to-day operations, and taking steps to avoid issues such as backstreaming.

Backstreaming occurs when oil doesn’t go down to the base of the pump like it should and instead gets drawn back up into the vacuum chamber. Backstreamed oil can react with heat and electrical discharge to produce deposits that contaminate the chamber walls and other pump parts. Such contamination can cause unwanted downtime and the eventual need to replace parts.

To avoid backstreaming and other problems that prevent your diffusion pump from working smoothly, follow these five simple operating tips.

1. Keep the Right Flow and Temperature in the Water Supply Line

If the water temperature is too high, the cooling coils won’t get the chamber walls cold enough to condense the vaporized pumping oil. Sluggish or blocked water flow also inhibits the cooling system, as the coils fail to get replenished with cold water and only heat up more from contact with the chamber walls. 

In either case, overheated conditions inside the vacuum chamber can cause a buildup of oil vapor and consequent backstreaming. Always keep your water supply line within the temperature and flow range recommended in the pump operator’s manual.

2. Ensure the Vacuum Chamber Is Airtight

If the vacuum chamber has any leaks, oxygen from the atmosphere flows into the pump. When heated oil is exposed to oxygen, the oil burns and will eventually require replacement. 

To protect the pumping oil and avoid taking your pump out of operation for service, check the vacuum chamber regularly for leaks.

Related: Find out how you can protect against leaks on our resource page, The Fundamentals of Leak Detection. Click the button below and dive in!

Explore the Resource Page


3. Make Sure Your Pump Has an Integrated Heating System

Some diffusion pumps need to be paired with a separate heating component. This kind of paired configuration can cause the pump to overheat, as the independent heater controls fail to adjust for conditions within the pump.

To avoid pump overheating, always use a pump model like the Leybold DIP or DIJ which has an integrated heating system and controls the heater temperature directly. Find out more about our oil diffusion vacuum pumps like the the Leybold DIP or DIJ, on our product page

4. Don’t Open the Backing Pump Valve at High Pressure

Opening the backing pump valve at high pressure doesn’t actually improve pumping performance. Instead, the increased pressure can blow the pumping oil away from the exhaust line and cause oil misting and backstreaming issues in the vacuum chamber.

Your diffusion pump will perform best when you keep the backing pump valve within the pressure range recommended in the pump operator’s manual.

5. Make Sure the Backing Pump Produces Adequate Flow

If your backing pump doesn’t have enough flow, high pressure can form in the exhaust line. This high pressure can result in unwanted oil misting and backstreaming in the vacuum chamber. Consult the pump operator’s manual for guidelines on maintaining the proper flow in your backing pump.

Get More From Your Diffusion Pumps

By following the proper care and operating practices, you will enjoy excellent, reliable service from your oil diffusion pump for years to come. If you need more advice on how to keep your diffusion pumps in peak condition, click the button below to get in touch, and our team will be happy to help.

Talk to Us


The above is intended only as a guide and is not a substitute for reading the operational manual. Always read the operational manual.

Tags: Heat Treatment, Industrial & Process Vacuum, Maintenance & Service

About Gene Ligman

Gene Ligman

Gene Ligman is an engineer with a passion for vacuum applications and equipment. He started his engineering career over 30 years ago in the nuclear power industry where he was first introduced to the utility of vacuum in steam systems and some basic vacuum generating equipment. In the mid 1990’s, he joined Edwards Vacuum where his knowledge of vacuum applications and equipment expanded exponentially.

Having a degree in mechanical engineering with a focus on vapor physics has propelled him to become one of the primary resources in applications where phase change creates complexities above and beyond the normal complexities of vacuum applications. Now with Leybold USA, Gene is a Sales Development Manager for Leybold’s largest and most industrial vacuum generating equipment. He trains the US organization in key insights about how the right vacuum equipment can radically improve the productivity and profitability of vacuum-using factories. These insights, along with his passion for vapor physics make him a leading authority in vacuum system design.

Read more articles by this author

Leak Detection 101

Download our e-Book "Fundamentals of Leak Detection" to discover leak detection essentials and techniques.