Controlled by-pass for a booster pump
AssigneeThe BOC Group, Inc.
InventorsSteven V. Morgan, John E. Madocks
Life of this patent
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Abstract
A method and apparatus for evacuating an enclosed chamber which utilizes a tandem connection of a booster pump and a mechanical pump in a manner to maximize the rate of evacuation of the chamber but without exceeding the rating of the booster pump and damaging it. A gas bypass around the booster pump is provided with a proportional valve that is operated to start an evacuation of the chamber with the bypass path fully opened but the gradually closing that path in a manner to maintain a differential pressure across the booster pump at a predetermined level, until the bypass path has been fully closed.
Claims10
A method of evacuating an enclosed chamber through a tandem connection of a booster pump and a mechanical pump, comprising the steps of:
- commencing pumping gas from said enclosed chamber by operating both of the booster and mechanical pumps,
- from the beginning os said pumping, providing a gas bypass around the booster pump, and
- as the gas pressure of the enclosed chamber drops, gradually closing off said bypass at a rate to maintain a pressure differential across said booster pump substantially at a given value until the bypass path is completely closed.
A method of evacuating a chamber initially at atmospheric pressure with a pumping system of a type including a booster pump having an inlet operably connected through a roughing valve to an interior of said chamber and a discharge connected to an intake of a mechanical pump, and a gas bypass path extending from the inlet to the discharge of said booster pump and having a valve therein, comprising the steps of:
- running said booster and mechanical pumps,
- opening the bypass path valve a maximum amount,
- opening said roughing valve,
- closing the bypass valve a partial amount until a difference in gas pressure between the inlet and discharge of the booster pump is a given value,
- continuing to incrementally close the bypass valve in a manner to maintain the difference in pressure between the booster pump inlet and its discharge substantially at said given value until said bypass valve is fully closed, and
- continuing to drive said booster and mechanical pumps until the chamber is evacuated to a desired gas pressure level.
Apparatus for evacuating gas from an enclosed chamber that is repeatedly opened to the atmosphere in order to gain access to the chamber, comprising:
- an evacuation passage provided to said chamber from its outside,
- means including a roughing valve in said passage for controllably opening and closing said evacuation passage,
- a booster pump having an intake connected to said evacuation passage and having a discharge,
- a mechanical pump having an intake connected to the discharge of the booster pump,
- a gas bypass path around said booster pump from its said intake to its said discharge,
- a proportionally controlable valve in said bypass path, and
- means responsive to a difference between the booster pump intake and discharge gas pressure for controlling the amount of opening of said proportionally controlled valve in a manner that maintains that gas pressure difference below a predetermined threshold.
Dependencies are inferred from the claim text.