CN100545609C - Adopt linear vacuum gauge to measure the device and method of orifice conductance - Google Patents

Abstract

The device that adopts linear vacuum gauge to measure orifice conductance is made up of aperture to be measured, vacuum valve, linear vacuum gauge, volumetric standard, micrometering valve, pressure stabilizing chamber, gas cylinder, vacuum pump, vacuum pump is connected with an end of aperture to be measured, aperture to be measured is connected to vacuum valve, vacuum valve is connected with volumetric standard simultaneously, volumetric standard is connected with pressure stabilizing chamber by micrometering valve again, micrometering valve is connected to gas cylinder, and linear vacuum gauge is connected on the volumetric standard, and vacuum valve one terminates on volumetric standard and the pressure stabilizing chamber; Adopt linear vacuum gauge to measure the method for orifice conductance, it is in the volumetric standard of V that the pure gas of a constant rate is introduced volume, and portion gas will be the aperture outflow volumetric standard of C by conductance to be measured; With the original pressure p in the linear vacuum gauge measurement standard container ₁, behind the elapsed time t, the pressure p in the measurement standard container ₂, the mobile equilibrium pressure p in the measurement standard container ₀, then orifice conductance C just equals (V/t) ln ((1-(p ₁/ p ₀))/(1-(p ₂/ p ₀))).The present invention has improved the measuring accuracy of orifice conductance, and the combined standard uncertainty that makes measurement result is less than 0.3%.

Description

Adopt linear vacuum gauge to measure the device and method of orifice conductance

Technical field

The present invention relates to a kind of device and method of measuring orifice conductance, particularly adopt linear vacuum gauge to measure the orifice conductance device and method.

Background technology

Document " constant volume method is measured the method research of orifice conductance, " vacuum " the 43rd volume, the 1st phase in 2006, the 62nd～66 page " has been introduced a kind of method of measurement orifice conductance.This method is earlier at the indoor gas that charges into certain pressure of the constant volume of known volume, measure the indoor original pressure of constant volume with absolute pressure formula capacitor thin film vacuum meter, gas is taken away by aperture, the pressure of constant volume chamber also just descends thereupon, measure variation of gas pressure amount in the certain hour room decided at the higher level but not officially announced with differential pressure type capacitor thin film vacuum meter, thereby can calculate the conductance of aperture, the combined standard uncertainty of orifice conductance measurement result is 1.1%.

The weak point of this kind method is exactly that the uncertainty of measurement result is big, and main cause is: used two different capacitor thin film vacuum meters to measure the indoor original pressure of constant volume and the variable quantity of pressure, thereby can not effectively utilize the linearity of vacuum meter; The uncertainty of measurement of every capacitor thin film vacuum meter is not less than 0.4%; Environmental temperature fluctuation is big to the measurement result influence of pressure variety.

Summary of the invention

The technical matters that the present invention solves is: overcome the deficiencies in the prior art, provide a kind of employing linear vacuum gauge to measure the orifice conductance device and method, the uncertainty of measurement of having avoided deviation of reading to introduce, make the uncertainty of measuring orifice conductance by former greater than 1%, be reduced to less than 0.3%.

Technical solution of the present invention is: adopt linear vacuum gauge to measure the orifice conductance device, its characteristics are: it is by aperture to be measured, three vacuum valves, linear vacuum gauge, volumetric standard, two micrometering valves, pressure stabilizing chamber, gas cylinder, two vacuum pumps are formed, first vacuum pump is connected with an end of aperture to be measured, the other end of aperture to be measured is connected to first vacuum valve, second vacuum valve is connected with an end of volumetric standard, the other end of volumetric standard is connected with pressure stabilizing chamber by first micrometering valve, pressure stabilizing chamber is connected to gas cylinder by second micrometering valve again, linear vacuum gauge is connected on the volumetric standard, one of second vacuum valve and the 3rd vacuum valve terminates on volumetric standard and the pressure stabilizing chamber, the other end and connect after be connected to second vacuum pump.Background pressure in described volumetric standard, pressure stabilizing chamber and the connecting tube is less than 1 * 10 ^-3Pa; The volume of described pressure stabilizing chamber satisfies in the conductance measuring process that pressure changes less than 0.01% in the pressure stabilizing chamber; Be filled with pure gas in the described gas cylinder.

Adopt linear vacuum gauge to measure the method for orifice conductance, realize by following steps:

(1) be that volumetric standard and the connecting line of V vacuumizes to volume, the background pressure of volumetric standard and connecting line is less than 1 * 10 ^-3Pa;

(2) pure gas of constant rate being introduced volume is in the volumetric standard of V, and portion gas then is the aperture outflow volumetric standard to be measured of C by conductance;

(3) adopt the interior original pressure p of linear vacuum gauge measurement standard container ₁, behind the elapsed time t, the termination pressure p in the measurement standard container ₂

(4) adopt the interior mobile equilibrium pressure p of linear vacuum gauge measurement standard container at last ₀

(5) then orifice conductance C just equals

The present invention's beneficial effect compared with prior art is:

(1) apparatus structure with linear vacuum gauge measurement orifice conductance is simple, owing to only use a linear vacuum gauge, causes that the component of uncertainty of measurement is also just few.

(2) linear vacuum gauge of measurement of vacuum does not require its measurement absolute pressure, just needn't know its calibration factor yet, thereby avoid because the uncertainty that calibration is introduced.Utilized the ratio of twice reading of linear vacuum gauge.

(3) method of measurement orifice conductance is simple, and it is low to measure cost, and uncertainty of measurement is little, less than 0.3%, can be applicable to fields such as gas meter, the calibration of minimum leak rate, the leak detection of minimum small opening, the accurate calibration of extreme high vacuum gauge.

Description of drawings

Fig. 1 measures the structural representation of orifice conductance device for the present invention adopts linear vacuum gauge.

Embodiment

As shown in Figure 1, measurement orifice conductance device of the present invention is by aperture 1 to be measured, first vacuum valve 2, second vacuum valve 9, the 3rd vacuum valve 11, linear vacuum gauge 3, volumetric standard 4, first micrometering valve 5, second micrometering valve 7, pressure stabilizing chamber 6, gas cylinder 8, first vacuum pump 12 and second vacuum pump 10 are formed, first vacuum pump 12 is connected with an end of aperture 1 to be measured, the other end of aperture 1 to be measured is connected to first vacuum valve 2, first vacuum valve 2 is connected with an end of volumetric standard 4, the other end of volumetric standard 4 is connected with pressure stabilizing chamber 6 with first micrometering valve 5, pressure stabilizing chamber 6 is connected to gas cylinder 8 by second micrometering valve again, linear vacuum gauge 3 is connected on the volumetric standard 4, one termination of second vacuum valve 9 and the 3rd vacuum valve 11 has on volumetric standard 4 and pressure stabilizing chamber 6, the other end and connect after be connected to second vacuum pump 10.

Measuring method of the present invention is as follows:

(1) open first vacuum pump 12 and second vacuum pump 10, two vacuum pumps are started working, open first vacuum valve 2, second vacuum valve 9 and the 3rd vacuum valve 11 again, (present embodiment is a volume 1.749 * 10 to volumetric standard 4 ^-3m ³, can choose as required), pressure stabilizing chamber 6 and each connecting tube state that is evacuated, background pressure is less than 1 * 10 ^-3Pa;

(2) close second vacuum valve 9 and the 3rd vacuum valve 11, make by second micrometering valve 7 and to be filled with pure gas in the gas cylinder 8 to pressure stabilizing chamber 6 regulating the qi flowing in the channels, wherein pure gas can be helium, argon gas or nitrogen etc., and the pressure stabilizing chamber volume can satisfy in the conductance measuring process that pressure changes less than 0.01% in the pressure stabilizing chamber;

(3) close second micrometering valve 7, regulate first micrometering valve 5, gas is flowed in the volumetric standard 4 with constant rate, note the reading p of vacuum meter 3 ₁(present embodiment is 7.738 * 10 ^-3Pa), elapsed time t (present embodiment is 720s, can choose as required) writes down the reading p of vacuum meter 3 afterwards again ₂(present embodiment is 1.793 * 10 ^-2Pa);

(4) when the reading of vacuum meter 3 no longer changes, when reaching the dynamic pressure balance, i.e. pressure in the volumetric standard not during time to time change, the reading p of record vacuum meter 3 ₀(present embodiment is 2.782 * 10 ^-2Pa);

(5) the conductance C formula of aperture 1 to be measured $C=\frac{V}{t}\ln \left(\frac{1-\frac{p_1}{{\mathrm{<figure-callout\; id="0"\; label="p"\; filenames="C20061008725000081.png"\; state="\{\{state\}\}">p</figure-callout>}}_0}}{1-\frac{p_2}{p_0}}\right)$ Calculate, the value of present embodiment is 3.115 * 10 ^-9m ³/ s;

(6) more accurate in order to measure, orifice conductance C is got the mean value of repeatedly measuring (present embodiment is got 5 times).

The relative combined standard uncertainty of the conductance C of aperture 1 of the present invention is less than 0.3%.

The computing formula of uncertainty $u_{c,r}\left(C\right)=\sqrt{\frac{{\left(\mathrm{\&Delta;V}\right)}^2}{{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="C20061008725000081.png"\; state="\{\{state\}\}">V</figure-callout>}}^2}+\frac{{\left(\mathrm{\&Delta;t}\right)}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20061008725000081.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}+\frac{{\left[\mathrm{\&Delta;}\left(\frac{p_1}{p_0}\right)\right]}^2}{{\left[\frac{\mathrm{Ct}}{V}(1-\frac{p_1}{p_0})\right]}^2}+\frac{{\left[\mathrm{\&Delta;}\left(\frac{p_2}{p_0}\right)\right]}^2}{{\left[\frac{\mathrm{Ct}}{V}(1-\frac{p_2}{p_0})\right]}^2}}.$

In the present embodiment $\frac{\mathrm{\&Delta;V}}{V}=0.11\%,$ $\frac{\mathrm{\&Delta;t}}{t}=0.14\%,$ $\frac{\mathrm{\&Delta;}\left(\frac{p_1}{p_0}\right)}{\frac{\mathrm{Ct}}{V}(1-\frac{p_1}{p_0})}=0.08\%,$ $\frac{\mathrm{\&Delta;}\left(\frac{p_2}{p_0}\right)}{\frac{\mathrm{Ct}}{V}(1-\frac{p_2}{p_0})}=0.14\%,$ Relative combined standard uncertainty=0.24% of aperture 1 conductance C then to be measured.

Claims (4)

1, adopt linear vacuum gauge to measure the device of orifice conductance, it is characterized in that comprising: aperture to be measured (1), three vacuum valves (2,9,11), linear vacuum gauge (3), volumetric standard (4), two micrometering valves (5,7), pressure stabilizing chamber (6), gas cylinder (8), two vacuum pumps (10,12), first vacuum pump (12) is connected with an end of aperture to be measured (1), the other end of aperture to be measured (1) is connected to first vacuum valve (2), first vacuum valve (2) is connected with an end of volumetric standard (4), the other end of volumetric standard (4) is connected with pressure stabilizing chamber (6) by first micrometering valve (5), pressure stabilizing chamber (6) is connected to gas cylinder (8) by second micrometering valve again, linear vacuum gauge (3) is connected on the volumetric standard (4), one end of second vacuum valve (9) and the 3rd vacuum valve (11) is connected on respectively on volumetric standard (4) and the pressure stabilizing chamber (6), the other end and connect after be connected to second vacuum pump (10); Background pressure in described volumetric standard (4), pressure stabilizing chamber (6) and the connecting tube is less than 1 * 10 ^-3Pa; The volume of described pressure stabilizing chamber satisfies in the conductance measuring process that pressure changes less than 0.01% in the pressure stabilizing chamber; Described gas cylinder is filled with pure gas in (8).

2, adopt linear vacuum gauge to measure the method for orifice conductance, it is characterized in that realizing by following steps:

(1) be that volumetric standard and the connecting line of V vacuumizes to volume, the background pressure of volumetric standard and connecting line is less than 1 * 10 ^-3Pa;

(2) pure gas of constant rate being introduced volume is in the volumetric standard of V, and portion gas then is the aperture outflow volumetric standard to be measured of C by conductance;

(3) adopt the interior original pressure p of linear vacuum gauge measurement standard container ₁, behind the elapsed time Δ t, the termination pressure p in the measurement standard container ₂

(4) adopt the interior mobile equilibrium pressure p of linear vacuum gauge measurement standard container at last ₀(5) then orifice conductance C just equals $\frac{V}{\mathrm{\&Delta;t}}\ln \left(\frac{1-\frac{p_1}{p_0}}{1-\frac{p_2}{p_0}}\right).$

3, employing linear vacuum gauge according to claim 2 is measured the method for orifice conductance, it is characterized in that: mobile equilibrium pressure is exactly the pressure pressure during time to time change not in the volumetric standard in the described step (4).

4, employing linear vacuum gauge according to claim 2 is measured the method for orifice conductance, it is characterized in that: orifice conductance C gets the mean value of repeatedly measuring in the described step (5).

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