CN102944358B - High and low temperature vacuum calibrating device and method - Google Patents

Abstract

The invention discloses a high and low temperature vacuum calibrating device and a high and low temperature vacuum calibrating method and belongs to the field of measurement. The device comprises a standard vacuum gauge, a three-way connecting piece, a calibrated vacuum gauge, a high and low temperature vacuum calibrating chamber, a monitoring vacuum gauge, a temperature control board, a refrigerating system, an air-bleed set, a valve, a gas supply system and a micrometering valve. According to the device and the method, the accurate calibration of the vacuum gauge at different temperature points in a temperature range of minus 140 DEG C to 100 DEG C in a range of 1*10<-4>Pa to 1*10<5>Pa can be implemented.

Description

A high and low temperature vacuum calibration device and method

technical field

The invention relates to a high and low temperature vacuum calibration device and method, in particular to realize the accurate calibration of vacuum gauges with a vacuum degree in the range of 1×10 ^-4 Pa to 1×10 ⁵ Pa and a temperature in the range of -140°C to +100°C The device and method belong to the field of measurement.

Background technique

Vacuum gauges are widely used in various fields of industrial production, and the research on calibration technology of vacuum gauges is an important research direction in the field of vacuum measurement. The document "Li Zhenghai. Method for Calibrating Vacuum Gauge with Composite Vacuum Standard. Vacuum and Low Temperature 3 (2), 1997." introduces a typical calibration device and method currently used in vacuum gauge calibration. The composite vacuum standard device adopts the method of combining dynamic and static, and combines three methods of calibrating vacuum gauges, dynamic comparison, static comparison and static expansion, on one vacuum standard. The calibration range of the device is 10 ^-4 Pa～10 ⁵ Pa, the uncertainty is less than 10%.

The disadvantage of this system is that the device does not take into account the influence of the temperature change of the working environment on the indication value of the vacuum gauge, and can only realize the calibration of the vacuum gauge at room temperature in the laboratory, which cannot meet the requirements of 1×10 ^-4 Pa～1×10 ⁵ Accurate calibration of the vacuum gauge at different temperature points within the temperature range of -140°C to +100°C within the Pa range. When the calibrated vacuum gauge is used in different working environments, it will cause a large measurement uncertainty.

Contents of the invention

The purpose of the present invention is to provide a high and low temperature vacuum calibration device and method, which can realize the temperature range of the vacuum gauge in the range of 1×10 ^-4 Pa to 1×10 ⁵ Pa in the temperature range of -140°C to +100°C Accurate calibration at different temperature points.

The purpose of the present invention is achieved by the following technical solutions:

A high and low temperature vacuum calibration device, the device includes: a standard vacuum gauge, a three-way connector, a calibrated vacuum gauge, a high and low temperature vacuum calibration chamber, a monitoring vacuum gauge, a temperature control board, a refrigeration system, an exhaust unit, a valve, Air supply system, fine-tuning valve;

The three-way connector includes three open ends A, B, and C. Among them, the C end is the intake end, and the C end is located in the middle of the straight pipe between the A end and the B end, perpendicular to the straight pipe, and the C end is connected to the A end. , The distance between the two ends of B is equal, and the inner diameters of both ends of A and B are equal, which can ensure that after the gas enters the tee connector from the C end, the pressure flowing to the two ends of A and B is equal. The A end is connected to the standard vacuum gauge, and the B end is connected to the ground The vacuum gauge to be calibrated is fixed on the temperature control board, the temperature control board is connected to the refrigeration system, the three-way connector, the vacuum gauge to be calibrated and the temperature control board are placed in the high and low temperature vacuum calibration room, and the vacuum gauge and the high The low temperature vacuum calibration chamber is connected, the air extraction unit is connected with the high and low temperature vacuum calibration chamber through a valve, and the gas supply system is connected with the high and low temperature vacuum calibration chamber through a fine-tuning valve;

Wherein, the gas supply system is a gas cylinder or an air bag, the high and low temperature vacuum calibration chamber is made of multi-layer reflective thermal insulation material, the temperature control board is a copper plate wrapped with a heating resistance wire, and the valve is an ultra-high vacuum all-metal gate valve ;The fine-tuning valve is an ultra-high vacuum all-metal fine-tuning valve. The standard vacuum gauge includes three capacitance film-type vacuum gauges with a measurement accuracy of 0.05% of the full scale, and the full scales are 0.02Torr, 10Torr, and 1000Torr respectively; The refrigeration scheme of the combination of the first-stage cold head and the compressor; the air extraction unit adopts the air extraction scheme of the combination of the turbomolecular pump and the mechanical pump.

The calibration method of the high and low temperature vacuum calibration device described in the present invention, the steps of the method are as follows:

① Turn on the standard vacuum gauge and monitoring vacuum gauge, and make the standard vacuum gauge stable for 24 hours;

② Start the pumping unit, open the valve, and pump air to the high and low temperature vacuum calibration chamber and pipeline; when the reading of the monitoring vacuum gauge shows that the vacuum degree of the high and low temperature vacuum calibration chamber is less than the ultimate vacuum degree of 1×10 ^-6 Pa, keep the calibration The state of the room is waiting for the follow-up operation;

③Open the trimmer valve and introduce the calibration gas in the gas supply system into the high and low temperature vacuum calibration chamber. When the gas pressure in the high and low temperature vacuum calibration chamber reaches equilibrium and the reading of the standard vacuum gauge reaches the required calibration pressure, close the trimmer Valve; start the refrigeration system and temperature control board, when the temperature in the high and low temperature vacuum calibration chamber is balanced and reaches the required calibration temperature, turn off the refrigeration system and temperature control board to maintain the temperature state in the high and low temperature calibration chamber; the gas pressure in the calibration chamber After reaching equilibrium, record the pressure reading p ₁ of the standard vacuum gauge and the pressure reading p ₂ displayed by the calibrated vacuum gauge respectively;

Calculate the standard pressure of the high and low temperature vacuum calibration chamber according to the formula (I),

$\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula: p - the standard pressure of the high and low temperature vacuum calibration chamber, unit: Pa;

T ₁ - the ambient temperature of the standard vacuum gauge, unit: K;

T - high and low temperature vacuum calibration indoor temperature, unit: K;

Calculate the calibration factor according to formula (II),

$\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; II</span>}<span\; class="notranslate">\; )</span>$

In the formula, c - is the calibration factor, dimensionless;

Wherein, the calibration pressure mentioned in step ③ is related to the measurement range of the vacuum gauge to be calibrated, and the calibration temperature range is -140°C to +100°C;

It is preferable to repeat step ③, select different calibration pressures and calibration temperatures each time, perform multiple measurements, and then average the calibration factors calculated for each measurement.

Beneficial effect

The device of the present invention utilizes a molecular pump and a mechanical pump exhaust unit with good performance, which can make the ultimate vacuum of the calibration device reach 1×10 ^-6 Pa; it adopts a refrigeration system composed of a cryopump primary cold head and a compressor , which can control the temperature range of the calibration device at -140°C to +100°C; at the same time, since the standard vacuum gauge with a measurement accuracy of 0.05% of the full scale is used to provide the standard pressure reading during calibration, the measurement uncertainty is reduced. Improved calibration accuracy.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the high and low temperature vacuum calibration device of the present invention;

Among them, 1—standard vacuum gauge; 2—tee connection; 3—vacuum gauge to be calibrated; 4—high and low temperature vacuum calibration room; 5—monitoring vacuum gauge; 6—temperature control board; 7—refrigeration system; 8—pumping Gas unit; 9—valve; 10—air supply system; 11—fine-tuning valve.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but is not limited thereto.

Example 1

As shown in Figure 1, a high and low temperature vacuum calibration device, said device includes: a standard vacuum gauge 1, a tee connector 2, a calibrated vacuum gauge 3, a high and low temperature vacuum calibration chamber 4, a monitoring vacuum gauge 5, a temperature control Plate 6, refrigeration system 7, air extraction unit 8, valve 9, air supply system 10, fine-tuning valve 11;

The three-way connector 2 includes three open ends of A, B, and C, wherein, the C end is the air intake end, and the C end is located in the middle of the straight pipe between the A end and the B end, perpendicular to the straight pipe, and the C end is connected to the straight pipe. The distances between the two ends of A and B are equal, and the inner diameters of both ends of A and B are equal, which can ensure that after the gas enters the tee connector 2 from the C end, the pressure flowing to the two ends of A and B is equal. The A end is connected to the standard vacuum gauge 1, and the B end The end is connected with the vacuum gauge 3 to be calibrated, the vacuum gauge 3 to be calibrated is fixed on the temperature control board 6, the temperature control board 6 is connected to the refrigeration system 7, and the three-way connector 2, the vacuum gauge 3 to be calibrated and the temperature control board 6 are placed In the high and low temperature vacuum calibration chamber 4, the monitoring vacuum gauge 5 is connected to the high and low temperature vacuum calibration chamber 4, the air extraction unit 8 is connected to the high and low temperature vacuum calibration chamber 4 through the valve 9, and the gas supply system 10 is connected to the high and low temperature vacuum calibration chamber through the trim valve 11. Chamber 4 connection;

Among them, the gas supply system 10 is a gas cylinder or an air bag, the high and low temperature vacuum calibration chamber 4 is a multi-layer reflective thermal insulation material, the temperature control board 6 is a copper plate wrapped with a heating resistance wire, and the valve 9 is an ultra-high vacuum full Metal flapper valve; the fine-tuning valve 11 is an ultra-high vacuum all-metal fine-tuning valve 11, and the standard vacuum gauge 1 includes three capacitance film-type vacuum gauges with a measurement accuracy of 0.05% of the full scale, and the full scales are 0.02Torr, 10Torr, and 1000Torr respectively ; The refrigeration system 7 adopts the refrigeration scheme of the combination of the first-stage cold head of the cryopump and the compressor; the air extraction unit 8 adopts the air extraction scheme of the combination of the turbomolecular pump and the mechanical pump.

The calibration method of the high and low temperature vacuum calibration device described in the present invention, the steps of the method are as follows:

① Turn on the standard vacuum gauge 1 and the monitoring vacuum gauge 5, and make the standard vacuum gauge 1 stable for 24 hours;

②Start the pumping unit 8, open the valve 9, and pump air to the high and low temperature vacuum calibration chamber 4 and the pipeline; when the reading of the monitoring vacuum gauge 5 shows that the vacuum degree of the high and low temperature vacuum calibration chamber 4 is less than the ultimate vacuum of 1×10 ^-6 Pa When the temperature is high, keep the state of the calibration room and wait for the follow-up operation;

③Open the fine-tuning valve 11, and introduce the calibration gas in the gas supply system 10 into the high and low temperature vacuum calibration chamber 4, when the gas pressure in the high and low temperature vacuum calibration chamber 4 reaches equilibrium, and the reading of the standard vacuum gauge 1 reaches 10 ^-3 Pa When the calibration pressure is in the order of magnitude, close the fine-tuning valve 11; start the refrigeration system 7 and the temperature control board 6, and when the temperature in the high and low temperature vacuum calibration chamber 4 is balanced and reaches the calibration temperature of -50°C, close the refrigeration system 7 and the temperature control board 6 , keep the temperature state in the high and low temperature calibration chamber; after the gas pressure in the calibration chamber reaches equilibrium, the pressure reading p ₁ of the standard vacuum gauge 1 is 3.25×10 ^-3 Pa, and the pressure reading p displayed by the calibrated vacuum gauge 3 ₂ is 2.65×10 ^-3 Pa; the ambient temperature of the standard vacuum gauge 1 is +23°C;

Calculate the standard pressure of the high and low temperature vacuum calibration chamber 4 according to formula (I),

$\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula: p - the standard pressure of the high and low temperature vacuum calibration chamber 4, unit: Pa;

T ₁ - the ambient temperature of the standard vacuum gauge 1, unit: K;

T - temperature inside the high and low temperature vacuum calibration chamber 4, unit: K;

Substitute p ₁ =3.25×10 ^-3 Pa, T ₁ =296K, T=223K into formula (I), and calculate the standard pressure p=2.82×10 ^-3 Pa.

Calculate the calibration factor according to formula (II),

$\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; II</span>}<span\; class="notranslate">\; )</span>$

In the formula, c - is the calibration factor, dimensionless;

Substituting p ₂ =2.65×10 ^-3 Pa and p=2.82×10 ^-3 Pa into formula (II), the calibration factor of the vacuum gauge 3 to be calibrated is calculated to be c=1.064.

Wherein, the calibration pressure described in step ③ is related to the measurement range of the vacuum gauge 3 to be calibrated, and the calibration temperature range is -140°C to +100°C;

It is preferable to repeat step ③, select different calibration pressures and calibration temperatures each time, perform multiple measurements, and then average the calibration factors calculated for each measurement.

The present invention includes but is not limited to the above embodiments, and any equivalent replacement or partial improvement under the principle of the spirit of the present invention will be considered within the protection scope of the present invention.

Claims (3)

1. A high and low temperature vacuum calibration method, the device used in the calibration method includes: a standard vacuum gauge (1), a tee connector (2), a vacuum gauge to be calibrated (3), and a high and low temperature vacuum calibration chamber (4) , Monitoring vacuum gauge (5), temperature control board (6), refrigeration system (7), air extraction unit (8), valve (9), air supply system (10), fine-tuning valve (11); The three-way connector (2) includes three open ends A, B, and C, wherein, end C is the air intake end, end C is located in the middle of the straight pipe between end A and end B, and is perpendicular to the straight pipe, and C The distance from the end to the ends of A and B is equal, the inner diameters of both ends of A and B are equal, the A end is connected with the standard vacuum gauge (1), the B end is connected with the calibrated vacuum gauge (3), and the calibrated vacuum gauge (3) is fixed on the On the temperature control board (6), the temperature control board (6) is connected to the refrigeration system (7), and the three-way connector (2), the vacuum gauge to be calibrated (3) and the temperature control board (6) are placed in high and low temperature vacuum calibration In the chamber (4), the monitoring vacuum gauge (5) is connected to the high and low temperature vacuum calibration chamber (4), the exhaust unit (8) is connected to the high and low temperature vacuum calibration chamber (4) through the valve (9), and the gas supply system (10 ) is connected with the high and low temperature vacuum calibration chamber (4) through the fine-tuning valve (11); It is characterized in that: the steps of the calibration method are as follows: ① Turn on the standard vacuum gauge (1) and the monitoring vacuum gauge (5), and make the standard vacuum gauge (1) stable for 24 hours; ②Start the exhaust unit (8), open the valve (9), and pump air to the high and low temperature vacuum calibration chamber (4) and the pipeline; when the reading of the monitoring vacuum gauge (5) shows the vacuum degree of the high and low temperature vacuum calibration chamber (4) When the ultimate vacuum is less than 1×10 ^-6 Pa, keep the state of the calibration room and wait for subsequent operations; ③Open the fine-tuning valve (11), introduce the calibration gas in the gas supply system (10) into the high and low temperature vacuum calibration chamber (4), when the gas pressure in the high and low temperature vacuum calibration chamber (4) reaches equilibrium, and the standard vacuum When the reading on the meter (1) reaches the required calibration pressure, close the fine-tuning valve (11); start the refrigeration system (7) and the temperature control board (6), and when the temperature in the high and low temperature vacuum calibration chamber (4) is balanced and reaches the required When the calibration temperature is set, turn off the refrigeration system (7) and the temperature control board (6) to maintain the temperature state in the high and low temperature calibration chamber; after the gas pressure in the calibration chamber reaches equilibrium, record the pressure reading p of the standard vacuum gauge (1) respectively ₁ and the pressure reading p ₂ displayed by the calibrated vacuum gauge (3); Calculate the standard pressure of the high and low temperature vacuum calibration chamber (4) according to formula (I), $\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$ In the formula: p - the standard pressure of the high and low temperature vacuum calibration chamber (4), unit: Pa; T ₁ - the ambient temperature of the standard vacuum gauge (1), unit: K; T - temperature in the high and low temperature vacuum calibration chamber (4), unit: K; Calculate the calibration factor according to formula (II), $\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; II</span>}<span\; class="notranslate">\; )</span>$ In the formula, c - is the calibration factor, dimensionless; Wherein, the calibration pressure mentioned in step ③ is related to the measurement range of the vacuum gauge to be calibrated (3), and the calibration temperature range is -140°C to +100°C. 2. A high and low temperature vacuum calibration method according to claim 1, characterized in that: the gas supply system (10) is a gas cylinder or an air bag, and the high and low temperature vacuum calibration chamber (4) is a multi-layer reflective thermal insulation Materials, the temperature control board (6) is a red copper plate wrapped with heating resistance wire, the valve (9) is an ultra-high vacuum all-metal plug-in valve; the fine-tuning valve (11) is an ultra-high-vacuum all-metal fine-tuning valve (11), standard The vacuum gauge (1) consists of three 0.05% capacitance thin-film vacuum gauges with full-scale measurement accuracy, and the full-scale ranges are 0.02Torr, 10Torr, and 1000Torr respectively; the refrigeration system (7) adopts a combination of cryopump primary cold head and compressor refrigeration scheme; the air extraction unit (8) adopts an air extraction scheme combining a turbomolecular pump and a mechanical pump. 3. A high and low temperature vacuum calibration method according to claim 1, characterized in that: repeat step ③, select different calibration pressure and calibration temperature each time, perform multiple measurements, and then calculate the calibration value obtained by each measurement The factors are averaged.

Images