Method of Pumping Gas
AssigneeEdwards Limited
InventorsPeter Hugh Birch, Michael Roger Czerniak
Life of this patent
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Abstract
A method of pumping a gas stream containing a condensable species and a light gas and an apparatus therefore, the method comprising the steps of conveying the gas stream to a multistage vacuum pump comprising an inlet stage and an exhaust stage downstream from the inlet stage, and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than said light gas to both inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.
Claims30
A method of pumping a gas stream containing a condensable species and a light gas, the method comprising the steps of:
- conveying the gas stream to a multistage vacuum pump having an inlet stage and an exhaust stage downstream from the inlet stage;
- and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than the light gas, the purge gas being selected so as to inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.
(canceled)
A method of pumping a gas stream containing a condensable species and a light gas having a flow rate of at least 20 slm, the method comprising the steps of:
- conveying the gas stream to a multistage vacuum pump having an inlet stage and an exhaust stage wherein the exhaust stage has a volume at least three times smaller than the inlet stage;
- and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than said light gas at a rate of at least 10 slm.
(canceled)
(canceled)
A vacuum pumping arrangement for pumping a gas stream containing a condensable species and a light gas, the pumping arrangement comprising:
- a multistage vacuum pump having an inlet stage and an exhaust stage downstream from the inlet stage;
- and a purge gas supply for adding to the gas stream upstream of or at the inlet stage a purge gas wherein the surge gas is heavier than the light gas, the purge gas being selected so as to inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.
(canceled)
A vacuum pumping arrangement for pumping a gas stream containing a condensable species and a light gas having a flow rate of at least 20 slm, the pumping arrangement comprising:
- a multistage vacuum pump having an inlet stage and an exhaust stage downstream from the inlet stage wherein the exhaust stage comprises a volume at least three times smaller than the volume of the inlet stage;
- and a purge gas supply for adding to the gas stream upstream of or at the inlet stage a purge gas heavier than the light gas at a rate of at least 10 slm.
(canceled)
Dependencies are inferred from the claim text.