Lab Waste Management | Assessments | Surplus Equipment | Surplus Chemicals | Efficient Appliances | Dry vs Oil Vacuum Pump

Pumps are an essential component of laboratories and choosing a new pump to purchase when retiring an old one can be tricky. Here we want to highlight a couple points of differences between dry (diaphragm/scroll) and oil pump. 

 

Dry pump / diaphragm / scroll (1 Torr)

Oil pump / rotary vane pump (10^-3 Torr)

  

Best for 

Aspiration of waste liquids (microbio), filtration, drying, evaporation, desiccator, and concentration

glove box, freeze dryers, Schlenk Lines, and molecular distillation

    

Complications 

Not deep enough 

- May evaporate the filtrate instead of collecting it, risking contamination

- prone to bumping and foaming, risking sample loss

    

Upfront price

$2-5,000, varies

Varies, but generally cheaper than dry pump of the same function

    

Operational Cost (cost of replacement, service, waste disposal, and labor)

- Possible replacement of diaphragm due to wear (annual change or less)

- Cold trap (dry ice, liquid nitrogen) - to protect oil from degradation 

- Oil mist filters - prevents vapors from escaping into lab air and coating surfaces 

- Oil change - a few times a year

    

Service intervals 

10-15,000 hours. 

If the usage is 20h/wk for 50wk/yr, servicing will be required every couple years

10,000 hours - oil change

    

Misc

Loud 

Low noise level (75-80 dBA)

    

In sum, knowing what the experiments need would help with the most suitable purchase for the lab with the potential of eliminating cold traps and frequent services.

Citation

[1]Economic Advantage of Oil-free Vacuum for Labs

[2]What is the difference between Rotary Vane and Diaphragm vacuum pumps?