The DRYSTAR 80 mechanism consists of a roots and inverted multistage claw mechanism. The single roots stage at the pump inlet followed by the three claw stages enables the mechanism to be more efficient in the lower pressure regions. The reversed second claw stage of the DRYSTAR 80 ensures the outlet of the first claw stage is directly in line with the inlet of the second stage allowing for the most direct and shortest gas path through the pump. The short simple high conductance gas path contributes to good vacuum performance, improved power utilization, excellent condensable vapour handling and the ability to pass particulates through the pump.

The three claw stages of the DRYSTAR 80 ensure a true non-contact, self valving (effective for light gas pumping), self cleaning mechanism (for harsh duty or particulate generating applications) and optimized internal temperature profile (for efficient vapour handling capability). The mechanism also allows the pump to be continually rated from atmospheric pressure.

GV Claw Cutaway (image shown is GV600)

The DRYSTAR 80 is equipped with a shaft seal purge facility (N2 or Compressed Dry Air [CDA]). This provides a gas barrier between the swept volume of the pump and the oil gear box protecting the seal from process ingress, and insures critical cleanliness from oil migration of the gear box to the swept volume. Where a compressed gas supply is not available an atmospheric seal purge kit can be used if the continuous operating pressure is below 133 mbar (100 torr) and the application is not toxic flammable or corrosive.

The Edwards EH/QMB500 mechanical booster pump features a unique hydrokinetic drive which will provided efficient fluid power transmission between the pump mechanism and motor. The pump automatically slows down at high pressures preventing the pump from overheating or the motor overloading. The EH/QMB500 can be turned on at the same time as the DRYSTAR 80 and immediately begins to assist in the pumping process. Pump down time to a particular pressure can therefore be greatly reduced as there is no need for pressure switches or by-pass valves. The EH/QMB500 is well protected from operator error or process upsets, a sudden inrush of atmospheric air merely cause the rotors to slow down, while the motor continues to turn at normal operational speed. In the event of solid ingestion causing rotor seizure the motor will not overload.

Hydrokinetic Drive

Dry vacuum pumps derive their superior performance by removing the requirement for a working fluid from the pumping (swept) volume. Many people already successfully utilize dry pumps, and do not even realize it.

A mechanical booster is a dry pump! If you operate a mechanical booster, you will be familiar with the low levels of maintenance and high levels of reliability, in comparison with the oil-sealed backing pump used in conjunction with it. A backing dry pump, such as the DRYSTAR 80 has many of the same design features as a mechanical booster, but unlike a mechanical booster is capable of exhausting to atmospheric pressure. The reliability and intervention required for a mechanical booster is a very good indication of what you will experience with a mechanical backing dry pump!

Specifically in the case of the DRYSTAR 80 and EH/QMB500 Mechanical Booster, the similarities are very strong. Both products have:
   • Seal arrangements which are designed to ensure lubricants remain outside the pumping mechanism. (A key technology for       reliable dry pumping performance).
   • Roller bearings at the ends of both rotor shafts, to ensure maximum support and mechanical reliability. (Bearing life determines       the time period for pump service. A mean time to failure of 5 years (24/7 running) with adherence to the recommended       lubrication schedule.*
                     Routine visual inspection of oil level and quality
                     Annual gearbox fluid replacement*
                     Annual high vacuum bearing re-grease

*The lubrication schedule is detailed in the working instructions of the pumps, and is impacted by both the pump application, and installation.

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