Dry running vacuum pumps

Dry vacuum pumps have been developed for the semiconductor industry in the 80's and introduced in chemical and pharmaceutical process industries in the early 90's. They are specified for fine chemicals and pharmaceutical (cGMP) plants in order to avoid a product contamination.

They are multistage roots systems or screw- or claw-compressors.

SIHIdry (screw pump) SIHIdry vacuum pump TAIKO (screw pump) TAIKO dry vacuum pump Northey (claw pump) Northey dry vacuum pump

Applications and Features
suction capacities up to approx. 1000 m³/h
Endvacuum lower than 1 mbarA

- pressure control through speed control
- compact
- good efficiency
- no contamination through oil or seal liquid

Advantages and Disadvantages

No auxiliary liquid = no lubrication-, no sealing- and no cooling-liquid
no lubrication means no contact between the parts = tight clearances (*)
no sealing means tight clearances and/or high speed
no cooling means high temperatures (**)

* tight clearances + high temperatures = body in cast iron only
** high gas temperature means hot spots: T3 is standard, T4 possible but relatively complicated.

no seal liquid (= no contamination)
= no product contamination
= vapours are condensed and recovered at pump outlet.

no contamination of auxiliary liquid (oil, motive steam, seal liquid, etc..)
= no cost for treatment and waste

BUSCH COBRA description BUSCH COBRA vacuum pump 1.Inlet - 2.Exhaust - 3.Water Jacket - 4.Screw - 5.Oil - 6.Gas Path - 7.Timing Gears - 8.Bearings - 9.Shaft Seals - 10. Oil Seal
Dry vacuum pumps - FAQ's

manufacturers and suppliers ?
  claw type vacuum pumps suppliers directory
  dry screw vacuum pumps suppliers directory

more than 1000 m³/h suction capacity ?
higher vacua and shorter pumpdown times can be achieved by combining the dry vacuum pump with roots type mechanical booster(s)

sealing between pump and gear ?
with piston rings or mechanical seals, with/without purge gas

how to avoid corrosion ?
operating temperature to be higher than product condensation temperature.
pre-heating with closed inlet valve, drying with N2 before shut-down.
outlet piping top to down or with a siphon to avoid bach-flow of condensate

SIHIdry: yes, without flame arrestors for Gases of Atex-categorie 2 (Zone 1)
BUSCH COBRA: yes, with flame arrestors for Zone 0 and Zone 1.

speed control ?
Yes, recommended instead of pressure control valve