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Mechanical Industry Standard of the People's Republic of China
JB/T7266-94
Performance measurement method of positive displacement vacuum pump
Published on July 18, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1995
Mechanical Industry Standard of the People's Republic of China
Performance measurement method of positive displacement vacuum pump
JB/T7266-94
This standard is equivalent to the international standards IS01607/1-1980 "Performance measurement method of positive displacement vacuum pump - Part 1: Measurement of volume flow rate (pumping speed)" and ISO1607/I-1980 "Performance measurement method of positive displacement vacuum pump - Part 2: Measurement of ultimate pressure". Subject content and scope of application
This standard specifies the measurement method of the pumping rate, ultimate pressure, power consumption and operating temperature of positive displacement vacuum pumps. This standard applies to the performance measurement of positive displacement vacuum pumps (hereinafter referred to as pumps) with an ultimate pressure lower than 100 Pa and capable of exhausting directly into the atmosphere.
2 Terminology
2.1 Pumping rate (volume flow rate)
Under ideal conditions, the volume of gas flowing through the pump port per unit time. In practical applications, the pumping rate (s) is defined as: when the pump operates under specified conditions, the ratio of the gas flow rate (q) flowing through the test hood to the equilibrium pressure (>) at the specified position is referred to as the pumping rate, that is, S=%L/s
2.2 Ultimate pressure
When the pump operates under specified conditions, the lowest pressure that tends to stabilize in the test hood without introducing gas, Pa, 2.3 Test hood
refers to a container with a specified shape and volume installed on the pump port. The measured test gas is filled into the pump through it, and a fine-tuning valve and a vacuum gauge are installed on it.
2.4 Power consumption
When the pump operates under specified conditions, the power required for the pump inlet pressure after the pump temperature is balanced. 2.5 Working temperature
When the pump operates under specified conditions And under the ultimate pressure, the equilibrium temperature measured near the exhaust valve is ℃3 Measuring device
3.1 Test hood
The hood is cylindrical (see Figure 1a). Its inner diameter is D and its height is 1.5D. The test gas inlet is located on the axis of the hood and faces away from the port. The distance from the flange plane is D. The vacuum gauge (or gauge) connecting pipe is 0.5D away from the flange plane and is perpendicular to the axis of the hood. The volume (V) of the hood should be at least five times the volume (V1) swept by one compression cycle of the pump. A reducing pipe joint with a length of no more than 0.5D needs to be connected between the hood and the pump port (see Figure 1b). The test hoods suitable for pumps of different specifications are given in Table 1. 3.2 Vacuum gauge
Different types and accuracy of vacuum gauges are selected according to the measured pressure. The calibration accuracy is: pressure Pressure is higher than or equal to 1Pa, within ±5%; pressure is lower than 1Pa, within ±10% Approved by the Ministry of Machinery Industry on July 18, 1994
Implementation on July 1, 1995
3.3 Flowmeter
>0.26~1.1
>17~65
>65~260
JB/T7266-94
Connect auxiliary air valve
Pump port diameter
Select flowmeters of different types and specifications according to the measured flow. The measurement accuracy is: flow greater than 1W, within ±3%;
flow between 1~10-*W, within ±5%; flow less than 10-*W, within ±10%. 3.4 Power meter and current transformer
Power meter and current transformer should have first-class accuracy and have valid certificates issued by the metrology department. 3.5 Thermometer
The error of the thermometer for measuring the working temperature shall not exceed ±1°C. 4
Measurement conditions
The following conditions shall be met during measurement:
JB/T7266-94
The difference between the actual speed of the pump and the rated value shall not exceed ±3%. The type and quantity of the pump fluid shall meet the design requirements; the cooling water flow and temperature of the water-cooled pump shall meet the design requirements; the ambient temperature shall be between 15 and 25°C, and the fluctuation during the measurement shall not exceed ±1°C; the measured gas shall be indoor air, and the relative humidity shall not exceed 75%; f
When measuring the gas-ballast pump, its air entrainment shall meet the design requirements. 5 Measurement method
5.1 Pumping rate measurement
5.1.1 Principle
The pumping rate of the pump is measured by the "constant pressure method". That is, during the flow measurement process, the pressure in the hood remains unchanged. 5.1.2 Steps
The pumping rate measurement device is shown in Figure 2.
Figure 2 Measurement device
In order to measure the pumping rate, the test hood, vacuum gauge and flow meter should be assembled on the pump. Close the fine-adjusting valve, start the pump, fully gas-ballast the pump with gas ballast, close the gas ballast valve, and the pump reaches the equilibrium temperature after the pressure does not drop further for 1 hour. Open the fine-adjusting valve and put the measuring gas into the hood to establish a set equilibrium pressure, and measure the gas flow at the same time. And calculate the pumping rate under this pressure according to formula (1).
The measurement should start from an appropriate value slightly higher than the ultimate pressure until atmospheric pressure or other pressures suitable for the pump structure characteristics. At least three points should be measured in each pressure order of magnitude, which are roughly 2.5, 5 and 10. If the flow measurement time is long, take 60s as a cycle, the pressure should be measured repeatedly, and the average value should be taken. If the difference between the highest and the lowest is greater than 10% of the average value, both the flow and pressure should be re-measured. For gas ballast pumps, the gas ballast valve should be fully opened after the above measurement, and the pumping rate during gas ballast should be measured again after the pump temperature is balanced again.
5.2 Ultimate pressure measurement
5.2.1 Principle
Install the specified test cover on the pump port and measure the ultimate pressure in the cover at the equilibrium temperature. 5.2.2 Steps
The ultimate pressure measuring device is shown in Figure 2.
JB/T7266-94
Close the fine-tuning valve, start the pump, and run it for at least 1 hour under gas ballast, and then run it for another 1 hour without gas ballast. Take pressure measurements at intervals of 30 minutes. When the results of three consecutive measurements show that the pressure no longer changes, the ultimate pressure is reached. Record the readings of the compression vacuum gauge and the total pressure vacuum gauge respectively, and keep two significant digits. For gas ballast pumps, the gas ballast valve should be fully opened after the above measurement, and the ultimate pressure during gas ballast should be measured again after the pump temperature is balanced again.
5.3 Power consumption measurement
5.3.1 Method
Use a power meter to measure the input power of the pump drive motor at various inlet pressures, and then multiply it by its efficiency under different loads to obtain the power consumption of the pump.
5.3.2 Steps
Close the fine-tuning valve and the auxiliary air inlet valve, start the pump, and after the pump temperature is balanced, open the fine-tuning valve and the auxiliary air inlet valve to make the pressure in the hood stable from low to high point by point, and measure the power value at the same time. In order to ensure that the measured value has the necessary accuracy, the power meter should not be used below half of the face value. The measured value should have two significant digits. For gas ballast pumps, after the above measurement, the gas ballast valve should be fully opened, and the power consumption during gas ballast should be re-measured after the pump temperature is balanced again.
5.4 Working temperature measurement
5.4.1 Measurement method
After the pump has been running for 1 hour at the ultimate pressure, fix the thermometer near the exhaust valve or other temperature measuring position and observe continuously for 30 minutes. If the temperature change does not exceed 1°C, the final temperature indicated by the thermometer is the working temperature of the pump. For gas ballast pumps, after the above measurement, the gas ballast valve should be fully opened, and the pump should continue to run for 1 hour, and then the working temperature during gas ballast should be measured. It is best to measure the working temperature at the same time as the ultimate pressure. 6 Measurement report
Fill in the "Vacuum Pump Performance Measurement Record Form" with the measurement results of the pumping rate, ultimate pressure, power consumption and working temperature, and draw the pumping rate-pressure curve (see Figure 3) and the power consumption-pressure curve (see Figure 4). /7
一Without gas ballast
一With gas ballast
Figure 3 Pumping rate-pressure curve
JB/T7266-94
Power consumption-pressure curve
A1 Vacuum gauge
JB/T7266-94
Appendix A
Vacuum gauge and pressure measurement
(Supplement)
According to the provisions on vacuum gauge accuracy in Article 3.2, the following vacuum gauges should be used: for pressures below 1.3×10°Pa, use a standard compression vacuum gauge; for pressures between 5.3×10° and 5.3×10°Pa, use an oil U-tube vacuum gauge; for pressures between 1×1055.3×10°Pa, use a mercury single tube or U-tube vacuum gauge. A2
Compression Vacuum Gauge
The standard compression vacuum gauge must have a valid certificate issued by the metrology department. The mercury used must have a 99.999% purity, and after sufficient filtration, cleaning and vacuum distillation, the gauge should be kept in vacuum when not in use.
Use nitrogen with a purity of not less than 99.9% to lift the mercury in the gauge. There shall be no rubber tube or glass valve with vacuum grease between the vacuum gauge and the test cover. The gauge should be equipped with a cold trap, and it is allowed not to inject refrigerant when measuring the pumping rate. The compression vacuum gauge adopts the calibration method without calibration". The speed of lifting mercury should not be too fast. After lifting, it should be stable for at least 1 minute before reading. A3 Oil U-tube vacuum gauge
The oil U-tube vacuum gauge (see Figure A1) should have a uniform tube diameter and a 1mm graduation scale. When the measuring oil is 20℃, the vapor pressure is lower than 0.133Pa and the kinematic viscosity is lower than 30×10-*m*/s; the density should be measured actually. The ultimate pressure of the pre-pump should be lower than 0.133Pa. Before use, it should be fully degassed; when measuring, the reading can be taken only after the liquid column is stable. Connect the pre-pump
Figure A1 Oil U-tube vacuum gauge
Connect the test cover
Selection of flow meter
JB/T7266-94
Appendix B
Flow meter and flow test
(reference)
According to For the flow test accuracy stipulated in Article 2.3, it is recommended to select the flow meter according to the following table. Table B1
Glass rotor type
Drop tube flow meter
Specifications or models
LZB-10
LZB-15
LZB-25
LZB-40
LZB-50
1.2×10-4~1.33 ×10-3 | t||1600~4530
Pa· L/s
1.2×10-~1.3
12~1.3×102
1.3×10~1.6×10
1.2×10°~1.4×104
1.5×10~4.5×104
4.3×10*~1.6×105
1.5×105~4.5×105
5.3×105~1.6×10*
1.6×10*~4.5×10
The structure of the dropper flowmeter is shown in Figure B1. The length of the measuring section (from scale line 1 to 2) is 200mm. The measurement accuracy of the measuring section volume is ±1%. The rubber tube connecting the fine-tuning valve should be as short and thin as possible. Oil tank The cross-sectional area should be greater than 180cm. The kinematic viscosity of the oil used for measurement at 20°C should be lower than 30×10-m2/s, and its density should be actually measured. The flow rate measured by the dropper flowmeter is calculated according to formula (B1): q=Vp[1+133.32(V.-V)hY/VpaJ/tWhere: q—measured flow rate, W;
measuring section volume, m\; wwW.bzxz.Net
pa.—measured atmospheric pressure, Pa;
V. 一一measurement before the total volume of the dropper from the oil surface to the fine-tuning valve seal, m\; h-the distance from the oil column rising from the scale line 1 to the scale line 2, mm; Y
一the ratio of the measured density of the oil to the density of mercury at 0°C (13.59); the time for the oil column to rise from the scale line 1 to the scale line 2 is specified to be t=25～300s. (B1)
Glass rotor flowmeter
JB/T7266-94
Dropper flowmeter
Glass rotor flowmeter should have 1.5 grade accuracy and should be used in the flow range of 60% to 100%. The measured flow is calculated according to formula (B2): 4 = Qps/3600×()
Where: 9-measured flow, w;
Q--flowmeter apparent value, m/h;
pa.t-measured atmospheric pressure, Pa;
pl-atmospheric pressure when the flowmeter is calibrated, take p=101325Pa; T, thermodynamic temperature when the flowmeter is calibrated, take T, =293K; T..Thermodynamic temperature at flow, K.
Additional remarks;
This standard is proposed by the National Technical Committee for Vacuum Technology Standardization. This standard is under the jurisdiction of the Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. This standard was drafted by Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. The drafter of this standard is Zhang Shufan.
According to the "National Standard for Industry Standards" adjusted to Appendix 3 of the State Technical Supervision Bureau's Technical Supervision Bureau's Standards (1992) No. 549, this standard replaces GB6306.16306.486.Thermodynamic temperature at flow rate, K.
Additional remarks;
This standard is proposed by the National Vacuum Technology Standardization Technical Committee. This standard is under the jurisdiction of the Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. The drafter of this standard is Zhang Shufan.
According to the "National Standard" adjusted to the industry standard in Appendix 3 of the Technical Supervision Bureau (1992) No. 549, this standard replaces GB6306.16306.486.Thermodynamic temperature at flow rate, K.
Additional remarks;
This standard is proposed by the National Vacuum Technology Standardization Technical Committee. This standard is under the jurisdiction of the Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shenyang Vacuum Technology Research Institute of the Ministry of Machinery Industry. The drafter of this standard is Zhang Shufan.
According to the "National Standard" adjusted to the industry standard in Appendix 3 of the Technical Supervision Bureau (1992) No. 549, this standard replaces GB6306.16306.486.
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