SU767592A1 - Method for calibrating vacuum gauges - Google Patents

Description

one

The invention relates to the field of instrumentation and can be used to determine the metrological characteristics of vacuum gauges.

 The known method of calibration of vacuum gauges, based on the calculated decrease (reduction) of pressure, originating from the molecular flow of gas through the diaphragms of known conductivity ClJ. The disadvantage of this method is the complexity of n | About maintaining calibration related to the need to measure pressure for each experimental point.

Also known is a simpler chronometric method of calibration of a vacuum in summer, based on the calculated pressure in the calibration chamber 2. This method is closest to the proposed one.

 The vacuum system, known as a known calibration method, is shown in FIG. one.

A calibrated gauge 2 is connected to the calibration chamber 1 (of known volume V). Through the diaphragm 3 of known low conductivity V ka, measure 1 is connected to chamber 4, to which is also attached an exemplary gauge 5.30

The method of calibration of vacuum gauges consists in that, after preliminary pumping out of chambers 1 and 4, chamber 4 is filled with gas and a continuous flow of gas from chamber 4 to chamber 1 is established through diaphragm 3, pressure P is measured in chamber 4 using an exemplary manometer 5. At the continuous pressure increase in chamber 1 is recorded (or recorded) the readings of the calibrated vacuum gauge 2 over time, starting from the moment of this the constancy of the pressure PT is monitored.

The pressure P-, of the gas in chamber 1, corresponding to arbitrary instants of time ti, is calculated by the formula

P; j; Р -v / v, Atj, (1) where t - to.

These calculated pressure values P- are compared with the corresponding readings of the vacuum gauge 2.

Claims (2)

The disadvantage of the method. calibration accuracy is low due to the presence of unreadable side gas processes in the calibration chamber (gas evolution from the chamber walls or inside a graduated vacuum gauge, at high and ultrahigh vacuum. Equation (1) assumes that the gas emission in the chamber is negligible and the vacuum gauge is negligible, it is not always fair. In addition, this stream is allowed to vary from one calibration cycle to another, therefore, the result of the fax survey contains a constant systematic error, The koTopoft increases with decreasing pressure ...,. The purpose of the invention is to improve the accuracy of calibration. This goal is achieved by the fact that after the increase in pressure is completed, the second chamber is pumped out, then the first chamber is connected to the second one, measured using a standard manometer After the pressure has been expanded, and ...:.:. a known dependence calculates the desired pressures in the first calibration Ksuviepe. A vacuum system implementing the proposed method of calibration of vacuum meters is shown in FIG. 2. It turns on chamber 1 of volume V with a calibrated gauge attached to it 2. Through diaphragm 3 of low conductivity chamber 1 is connected to chamber 4 of volume V, to which model gauge 5 is also connected. Diaphragm 3 can be opened or closed using valve 6. Parallel to it valve 7 is placed, with which —.- chambers 1 and 4 can be combined into a single chamber. Through valve 8, chamber 4 communicates with an additional pump 9 (or unit) designed to pump this chamber. The proposed method of calibration of vacuum gauges consists in the fact that the pos: —the preliminary pumping of chambers 1 and 4 fills the gas chamber 4 and establishes a continuous flow of gas from chamber 4 to chamber 1 through diaphragm 3 (with valves 7 and 8 closed and valve 6 is open) 1 With continuous pressure increase in the calibration KeiMepe 1, the readings of the calibrated vacuum gauge 2 are recorded (or recorded) with time, starting with t, (while monitoring the constancy of pressure P, in chamber 4). - Pressure P of gas in chamber 1, corresponding to arbitrary points in time t, is described by the equation sp. - -3-1 - (hm, where- qg is the total flow of sorption and gas removal in chamber 1. At some final NfoMenT time, pressure P, in chamber 1 in {VV where A tt - To Shut at time t valve 6 and opening valve 8, pump out chamber 4 with additional pump 9 (or unit) to pressures that are negligible compared to the final pressure P in chamber L. Then, closing valve 8 and opening valves 6 and 7, chamber 1 connects and 4. Then, in the total volume V + V of both chambers, pressure P is established. Next, pressure P is measured using an exemplary manometer 5. Solving, together, equation (2), (2a) and (3) with respect to pressure P, we obtain. These calculated values of pressure P in calibration chamber 1 are compared with the corresponding recorded time t of vacuum gauge indicators 2. Calculated values of pressure P for equation (A) are free of errors associated with side separation processes in calibration chamber and graduated vacuum gauge, which ensures that the calibration accuracy is slowed down; these side processes are automatically taken into account when measuring pressure The invention formula Calibration method vacuum gauge by increasing the pressure in the first chamber with a graduated gauge, continuous supply of lime gas to the chamber from the second chamber with an exemplary manometer, O11 pressure loss corresponding to the calibrated gauge recorded at some points in time, Q t l and h And in order to improve the accuracy of calibration, after the increase in pressure, the second chamber is pumped out, then the first chamber is connected to the second chamber, the pressure established after expansion is measured For example, the required pressures in the first chamber are calculated using a standard manometer and a known dependence. Sources of information taken on attention by the expert 1. Davis W.p.J.Vac.Sei.Teehnol .5, 1 (1968) p. 23-33. 2. IXushman S., Found t.J. Phys, Rev 15, 2 (1920), p. 133 (prototype). .iSirfiSiSj c .. / I / I /  ut. f