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Diaphragm Vacuum Pumps

What is a Diaphragm Vacuum Pump?

Diaphragm Vacuum Pumps are dry pumps that operate using a pulsing motion that opens and closes valves to move air. Oil is not required with this design. The valves are commonly made of polytetrafluoroethylene, making the pump more resistant to corrosives and vapor damage. While they could be more expensive upfront, they do not require oil, therefore their operation and maintenance costs are significantly lower than pumps that do. Diaphragm pumps can handle highly viscous liquids and a wide range of samples, but their application is limited to those requiring higher ultimate vacuum levels.

Diaphragm pumps are among the most chemically and corrosion-resistant pump types. Therefore, these pumps can handle almost any type of sample, including ones containing a combination of solvents and acids, making them a great choice for both evaporation and concentration.

Benefits of Diaphragm Pumps

  • Oil-free
  • Low cost of ownership
  • Highest reliability
  • Less maintenance saves time and money
  • Allows for a cleaner workplace and surroundings
  • Uncontaminated pumping of gases results in cleaner samples and no risk of oil back-streaming

Differences Between Rotary Vane and Diaphragm Vacuum Pumps

Rotary Vane Vacuum Pumps

Moving vanes are used in rotary vane pumps to transfer gas quantities through the system and out of the output. This style of operation requires the use of oil in the system to lubricate the moving parts and create a seal that isolates the gases. As a result, Rotary Vane pumps require frequent maintenance, such as changing the oil. Many units contain a sight glass to easily view the oil and gauge when it needs changing. Because rotary vane pumps can achieve significantly lower vacuums than diaphragm pumps, they're frequently utilized in more demanding applications like glove boxes and freeze dryers.

Diaphragm Vacuum Pumps

Diaphragm pumps are typically oil-free and low maintenance. They work by moving a flexible diaphragm that allows air to flow in one direction and out the other via control valves.

There is less maintenance required because this operation does not require oil. Depending on how often the diaphragm is used, it may need to be replaced annually or even less often.

Diaphragm pumps do not accomplish as low vacuums as Rotary Vane pumps but are a common choice for daily use with filtrations, desiccators, and aspiration of waste liquid in microbiology. Larger diaphragm pumps for use with rotary evaporators or vacuum ovens are also available.

Rules for Diaphragm Vacuum Pump Success

Select the appropriate pump.

If your applications involve corrosive gases or vapors, including acids, organic solvents, or even bleach, choose a pump with chemical-resistant wetted surfaces. The corrosive vapors will shorten the life of pumps built for non-corrosive environments.

Read your manual.

For safe operation and periodic pump maintenance, follow the manufacturer's instructions.

Protect the pump from particulates and liquids.

Equip your pump with an inlet separator, a glass “catch pot” that captures particulates and liquids before they enter the pump so that your pump sees only vapors and gases.

Keep the risk of condensable vapors to a minimum.

If you are operating with condensable vapors, use the pump’s gas ballast to keep condensation from accumulating in the pump. Since liquids are not compressible, they can cause damage to the pump mechanism.

Never block the outlet of the pump.

Blocking the exhaust from the pump can damage valves within the pump, leading to loss of vacuum and service downtime for repair.

Protect lab staff and the environment.

Utilize emission condensers on your pump to collect waste solvent vapors and capture them for reuse or proper disposal.

Clean the pump before storage.

Run the pump for a few minutes with the gas ballast valve open after your activity to blow any residual vapors through the pump before storage. This removes gasses that, if left unchecked, could condense in the pump when it cools after shutdown, causing corrosion during storage.

Diaphragm pumps became the workhorse in laboratories where smaller pumping speeds and ultimate pressures above a few mbars are enough. They replaced the water-polluting water jet pumps. They are also found in several high vacuum systems as small dry backing pumps today. To learn more about Diaphragm vacuum pumps, visit our website or call our dedicated vacuum pump specialists.