Generation of high vacuums
First Claim
1. A method for evacuating a receptacle using a pumping arrangement composed of a backing pump connected to the receptacle and a fine or high vacuum pump connected to the receptacle via a cold trap, comprising:
- initially evacuating the receptacle only by operation of the backing pump;
measuring the time taken to achieve a predetermined initial pressure reduction in the receptacle only by the action of the backing pump;
calculating, on the basis of the magnitude of such pressure reduction and the measured time period, the subsequent time period which would be required, if the effect of condensable gases in the receptacle were ignored, to reach a predetermined second pressure, lower than the first pressure, in the operating range of the fine or high vacuum pump; and
evacuating the receptacle by operation of the fine or high vacuum pump at the expiration of the subsequent time period.
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Accused Products
Abstract
In order to evacuate a receptacle using a pumping arrangement composed of a backing pump connected to the receptacle and a fine or high vacuum pump connected to the receptacle via a cold trap, the receptacle is initially evacuated only by operation of the backing pump, the time taken to achieve a predetermined initial pressure reduction in the receptacle only by the action of the backing pump is measured, then, on the basis of the magnitude of such pressure reduction and the measured time period, the subsequent time period which would be required, if the effect of condensable gases in the receptacle were ignored, to reach a predetermined second pressure, lower than the first pressure, in the operating range of the fine or high vacuum pump is calculated, and the receptacle is then evacuated by operation of the fine or high vacuum pump at the expiration of the subsequent time period.
59 Citations
9 Claims
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1. A method for evacuating a receptacle using a pumping arrangement composed of a backing pump connected to the receptacle and a fine or high vacuum pump connected to the receptacle via a cold trap, comprising:
- initially evacuating the receptacle only by operation of the backing pump;
measuring the time taken to achieve a predetermined initial pressure reduction in the receptacle only by the action of the backing pump;
calculating, on the basis of the magnitude of such pressure reduction and the measured time period, the subsequent time period which would be required, if the effect of condensable gases in the receptacle were ignored, to reach a predetermined second pressure, lower than the first pressure, in the operating range of the fine or high vacuum pump; and
evacuating the receptacle by operation of the fine or high vacuum pump at the expiration of the subsequent time period. - View Dependent Claims (2)
- initially evacuating the receptacle only by operation of the backing pump;
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3. Apparatus for evacuating a receptacle comprising:
- a backing pump;
a fine or high vacuum pump;
a cold trap connected by a line to the suction side of said vacuum pump;
means selectively connecting at least one of said pump and said cold trap to the receptacle; and
control means connected for determining the time taken to effect a predetermined pressure reduction in the receptacle by operation of only said backing pump, and for selectively connecting said vacuum pump to effect evacuation of the receptacle starting at a time after beginning of the predetermined pressure reduction which is a selected multiple of the determined time. - View Dependent Claims (4, 5, 6, 7, 8, 9)
- a backing pump;
Specification