Chemical Diaphragm Pumps for Lab and Industrial Applications

Rugged, Low-Maintenance Chemical-Resistant Diaphragm Pumps Suitable for a Broad Spectrum of Demanding Vacuum Processes


A chemical diaphragm pump is a type of positive displacement pump that uses a flexible diaphragm to move vapors without contamination. Welch offers a wide range of chemical-resistant diaphragm vacuum pumps that are designed to handle corrosive or aggressive media. These dry-running pumps ensure clean, completely oil-free operation, outstanding durability and reliability, as well as a low total cost of ownership.

Our offering comprises pumps with various flow and vacuum ranges, as well as multiple configurations to address the needs of a large number of processes. We provide diaphragm vacuum pumps with one, two, four or eight heads. Our portfolio includes both single-stage and multi-stage models, with (ecoflex pumps) and without pumping speed control.


Welch Chemical Diaphragm Vacuum Pumps: Key Design Features


Thanks to the use of PTFE heads, perfluoroelastomer valves and fluorinated plastic wetted surfaces, the pumps are defined by their superior resistance to aggressive solvents and acid vapors. Special X2 versions with higher grade seals and thicker coatings are available for applications in which the pump needs to handle particularly harsh chemical vapors.

Apart from outstanding technical specifications and build quality, Welch chemical diaphragm pumps are characterized by their quiet operation and very low vibration levels, which make them the perfect fit for various laboratory settings. Their low-weight compact designs mean they can be easily moved between locations and thus be used in many different applications.

Thanks to the state-of-the-art ecoflex feature, you can vary the pumping speed and adjust the vacuum precisely according to your individual needs. This results in more efficient and more reproducible processes. Using ecoflex pumps allows for reducing operational costs by up to 80%.


Your Main Benefits at a Glance


Welch’s chemical-resistant diaphragm vacuum pumps provide you with a number of benefits to help you improve and streamline your mission-critical vacuum processes. They include:

  • Dry operation – the oil-free design makes the pumps suitable for any rough to fine vacuum application requiring analytically pure, oil-free flow.
  • Extreme chemical resistance – the right material selection means our pumps are used in even the most demanding chemical-duty applications. Their anti-corrosion design features include PTFE-layered diaphragms with fiber reinforcement, PTFE heads, PTFE connection heads, PVDF/PP fittings, ECTFE-coated tension washers and PEEK valves. Many of the models have ATEX (category 3) certifications or offer ATEX (category 2) conformity.
  • Superior dependability – the pumps stand out through their durability, ensured by a maintenance-free drive system and long-lasting, chemical-resistant diaphragms.
  • Great flexibility – a wide selection of models with different vacuum and flow ranges, multiple wetted parts and diaphragm materials, and various head (elevated and extended) options makes our chemical diaphragm pumps the first choice for most laboratory applications.
  • Enhanced capabilities – Welch’s chemical-duty diaphragm vacuum pumps offer significantly superior flow and vacuum performance in the critical range of a given application. Their stable applied vacuum results in more repeatable operations and more reliable process results.
  • Easy maintenance – our chemical-duty diaphragm vacuum pumps are easy to operate and are defined by their fast and simple maintenance and service requirements.


Key Applications


Welch’s chemical-resistant diaphragm vacuum pumps are used in numerous laboratory and industrial applications where they support processes such as:

  • Rotary evaporation
  • Vacuum oven
  • Desiccation
  • Vacuum distillation
  • Vacuum filtration
  • Gel drying
  • Vacuum concentration
  • Gas sampling