TYPES OF VACUUM PUMPS
Vacuum pumps are used in a variety of process plants to pump air, water vapor, organic and inorganic solvents and acids. There are many different types of vacuum pumps on the market today that meet special needs in pumping various gases.
Liquid ring vacuum pumps are used for moderate to heavy vapor load conditions. A liquid sealant is used with operational vacuum limited to about 30 Torr. Lower vacuum obtainable with the use of oil, glycol or other low vapor pressure fluid. This type of pump Is desirable because it can be sealed with a fluid compatible with the process gas/vapor that would harm other type of pumps (i.e.: oil sealed) and is relatively inexpensive. Reliability is high because of it's simplicity.
Rotary vane vacuum pumps are oil sealed pumps used for pumping clean, dry, non-reactive gases. Since oil is used as it's sealant/lubricant the practical vacuum limitation is around 5 Torr. These pumps are usually air-cooled, direct-drive 1750 rpm pumps with a small footprint for space savings. Reliability is average with regular oil changes and periodic vane/filter changes required to keep maximum up-time. Pricing is very moderate given the vacuum they produce.
Rotary piston vacuum pumps are industrial grade heavy duty pumps made to produce a vacuum in the range of 50-.1 Torr. These pumps are used where contaminates are high and must be handled by the pump. Reliability is moderately high given the abuse these pumps are subjected to. Pricing reflects the performance of these pumps as high vacuum producers while also being able to handle large amounts of contaminates.
DRY VACUUM PUMPS:
Dry vacuum pumps are machines that compress gasses without the aid of a sealing fluid such as oil or water. They are used in extremely corrosive applications where pump failure will occur, or where environmental concerns are present. Vacuum range is from atmosphere to .10 mm Hg. Designs include SCREW, LOBE, CLAW.
Rotary lobed "Roots" vacuum boosters are used to extend the vacuum level and/or the pumping capacity of the vacuum pump by a factor of 2-10. The boosters are gas "accelerators" which increase the flow rate of gas being fed to the vacuum pump therefore increasing the capacity of the existing vacuum equipment.