JB/T 8941.2-1999 Roots blowers for general use Part 2: Performance test methods
Some standard content:
JB/T8941.2—1999
This standard is a revision of ZBJ72031-89 "Roots blower for general purpose, performance test method" based on ISO1217:1996 (E) "Positive displacement compressor-Acceptance test". This standard is equivalent to ISO1217:1996 (E) in terms of technical content, but since the standard does not provide a test device, this standard adopts the test device with flow regulator in Japanese Industrial Standard JISB8341:1995 "Positive displacement compressor-Test and inspection method". JISB83411995 is a revised version based on ISO1217:1986, and its main technical content and test device meet the requirements of ISO1217:1996 (E).
Compared with ZBJ72031-89, the main technical content of this standard has changed as follows: 1. All SI units are adopted.
2. Chapter 3 Definitions and Chapter 4 Symbols, Units and Subscripts were added. 3. Test methods for group-type Roots blowers, two-stage Roots blowers and negative pressure Roots blowers were added. 4. The diagrams of the test device were revised. 5. In terms of calculation methods, the influence of humidity on gas characteristics was introduced, and the correction method of the technical parameters of Roots blowers was proposed based on the working principle and leakage characteristics of Roots blowers. This standard is the second part of the JB/T8941 "General Purpose Roots Blowers" series of standards, which includes the following two parts: JB/T 8941.1-1999
JB/T 8941.2—1999
General Purpose Roots Blowers Part 1: Technical Conditions - General Purpose Roots Blowers Part 2: Performance Test Methods This standard replaces ZBJ72031-89 from the date of implementation. Appendix A of this standard is the appendix of the standard.
Appendix B of this standard is a prompt appendix.
This standard is proposed and submitted by the National Technical Committee for Standardization of Blowers. The responsible drafting unit of this standard is Changsha Blower Factory. The participating drafting units of this standard are Shanghai Blower Factory, Tianjin Blower Factory, Zhangqiu Blower Factory and Wuhan Blower Factory. The main drafters of this standard are Zhu Guixiu and Liu Zhilong. 455
1 Scope
Machinery Industry Standard of the People's Republic of China
Roots type blowers for general purpose
Part 2: Performance test methods
Roots type blowers for general purposePart 2:Performance test methodsThis standard specifies the performance test methods for Roots type blowers for general purpose. JB/T8941.2—1999
Replaces ZBJ72031—89
This standard applies to the performance test of Roots type blowers for general purpose (hereinafter referred to as blowers). In special cases, and for blowers used to transport special gases, the manufacturer and the purchaser may negotiate to refer to this standard for performance tests. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T2624-1993 Flow measurement device Measuring the flow of fluids filling a circular tube with an orifice nozzle and a venturi tube GB/T2888-1991 Noise measurement method for fans and Roots blowers GB/T11347-1989 Field measurement and evaluation of vibration intensity of large rotating machinery JB/T8941.1-1999-General purpose Roots blower Part 1: Technical conditions 3 Definitions
3.1 Standard suction position
A representative suction position specified for each blower, which varies with the structure and configuration of the blower. Note
1 The standard suction position of a single-stage blower is at the suction flange. 2 The standard suction position of a two-stage blower is at the suction flange of the first-stage blower. 3 The standard suction position of a group-type blower is the suction start of the blower device. 3.2 Suction state
The state of the sucked gas at the standard suction position of the blower. 3.3 Specified suction state
The suction state of temperature, pressure, humidity, etc. specified in the product sample or contract. 3.4 Standard exhaust position
The representative exhaust position specified for each blower, which varies with the structure and configuration of the blower. Note
1 The standard exhaust position of a single-stage blower is at the exhaust flange. 2 The standard exhaust position of a two-stage blower is at the exhaust flange of the second-stage blower. 3 The standard exhaust position of a group-type blower is at the exhaust flange of the exhaust terminal. 3.5 Specified speed
Approved by Guohao Machinery Industry Bureau on July 12, 1999 456
Implemented on January 1, 2000
JB/T8941.2—1999
The number of revolutions per unit time of the blower main shaft under the specified operating conditions. 3.6 Ambient pressure
The absolute atmospheric pressure measured near the blower. 3.7 Suction pressure
The gas pressure at the standard suction position, which refers to the static pressure of the inhaled gas. 3.8 Exhaust pressure
The gas pressure at the standard exhaust position, which refers to the static pressure of the discharged gas. 3.9 Suction temperature
The stagnation temperature of the gas at the standard suction position. 3.10 Exhaust temperature
The stagnation temperature of the gas at the standard exhaust position. 3.11 Ambient temperature
The stagnation temperature of the atmosphere near the blower but not affected by the blower. 3.12 Actual volumetric flow
The volumetric flow of the blower exhaust gas measured at the standard exhaust position, which should be converted to the state of the specified suction state (temperature, pressure, humidity and gas composition).
3.13 Shaft power
The power required to drive the blower main shaft, equal to the sum of the theoretical power and mechanical losses, but excluding external transmission losses such as couplings or belt drives.
3.14 Volumetric specific energy
The shaft power required for the blower per unit standard volumetric flow. Symbols, units and subscripts
Symbols, units and subscripts are shown in Tables 1 and 2. Table 1 Symbols and units
Correction factor
Volume flow
Gas constant
Celsius temperature
Thermodynamic temperature (T=273+t)
Equal entropy index
Pressure ratio
Relative humidity
Pressure difference before and after the orifice plate (△p=puppdowa) SI unit
J/(kg·K)
Other practical units
m\/min
Measurement equipment, method and accuracy
5.1 Pressure measurement
5.1.1 General
JB/T 8941.2—1999
Table 1 (end)
Orifice throttle diameter
Inner diameter of measuring pipe
Diameter ratio (β=d./D,)
Flow coefficient
Expansion coefficient
Impeller outer diameter
Impeller length
Volume utilization coefficient
Table 2 Subscripts
Environmental state
Absolute
Actual
Atmospheric
Specified
Corrected
Downstream of orifice
Read
Blower main shaft
Theoretical
Upstream of orifice
Volume
Saturated water vapor
SI unit
Other practical units
kw·h/m3
Indicates the quantity measured at the standard suction position of Roots blowerIndicates the quantity measured at the standard exhaust position of Roots blower5.1.1.1 The pressure measuring hole of the pipeline should be perpendicular to the inner wall and flush with the inner wall, and no burrs should be allowed. 5.1.1.2 The pressure gauge connecting pipe should be as short as possible, and the connection parts should be tested for sealing (for example, with soap solution) to eliminate all leaks; and they should have sufficient diameter and be reasonably arranged to avoid clogging by dirt. 5.1.1.3 The instrument should be properly installed to avoid the influence of vibration, etc. 5.1.1.4 The accuracy of the measuring instrument is ±1%. 5.1.1.5 Atmospheric pressure shall be measured by a mercury barometer with an error of less than ±40Pa. 458
5.2 Temperature measurement
JB/T 8941.2--1999
5.2.1 Certified or calibrated instruments shall be used, such as a thermometer with an accuracy of 1K, a thermocouple, a resistance thermometer or a thermistor inserted into a tube or sleeve to measure temperature.
5.2.2 Thin-walled small-diameter tubes shall be used as temperature sleeves as much as possible. At the same time, their outer surfaces shall be treated with anti-corrosion and anti-oxidation treatments, and the sleeves shall be filled with appropriate liquids
5.2.3 The thermometer or sleeve should be inserted into the pipe at a distance of 100mm or 1/3 of the pipe diameter from the inner wall of the pipe, whichever is smaller. 5.2.4 When reading, the thermometer shall not be removed from the measured medium. If there is a sleeve, it shall not be removed from the sleeve. 5.2.5 Measures should be taken to ensure that:
a) The connection parts close to the insertion point and the protrusion are well insulated so that the temperature of the sleeve and the measured medium are the same. b) The sensors or thermometer sleeves of various temperature measuring instruments should allow the measured medium to flow well (the sensor or thermometer sleeve should be inserted obliquely against the flow; in extreme cases, it is allowed to be positioned perpendicular to the air flow). c) The thermometer sleeve shall not disrupt the normal flow. 5.2.6 Thermocouples should have a welded hot end and should be calibrated together with the wire according to the predetermined range of use. The material of the thermocouple should be suitable for the measured medium and the temperature used. If the thermocouple uses a thermometer sleeve, the hot end should be welded to the bottom of the sleeve as much as possible. 5.3 Humidity measurement
If the gas contains moisture, the humidity should be checked during the test. The humidity check should be carried out as close to the standard suction position as possible, and measured with a ventilation psychrometer (Assmann hygrometer) with an accuracy of ±2%. 5.4 Speed measurement
Measured with a tachometer with a stopwatch, a photoelectric tachometer or other instrument, the accuracy of the measuring instrument shall not be less than ±0.2%. 5.5 Flow measurement
5.5.1The volume flow shall be measured with an orifice plate, and the structure and dimensions of the orifice plate shall be in accordance with Figure 1. 5.5.2The pressure taking method adopts angle connection pressure taking, and its structure and dimensions shall be in accordance with Figure 1. 5.5.3The size of the orifice plate is generally required to meet the following conditions: the inner diameter of the measuring pipe is in the range of 50 to 1000 mm, the square of the diameter ratio is equal to 0.05~~0.64, and the pressure difference before and after the orifice plate is above 500 Pa.
5.5.4 The technical requirements of the orifice plate, the use of the measuring device and the installation requirements shall comply with the provisions of GB/T2624. Orifice plate
F=30°～~45°
e= (0. 005 ~0. 02) D
E= e ~ 0. 05 Da
a) Annular gap pressure port
D-Inner diameter of the measuring pipe 50~1000mmsF—Diffusion angle, (°); Orifice plate
1 F=30*~45
e= (0.005~0.02)D
b) Drill a pressure port separately
Q-single hole diameter or slit width [when β≤0.65, α0.03D=β>0.65, 4≥(0.010.02)D: for any 3 values, a=1~10], mmf-slit thickness, mm;j-pressure pipe connection hole diameter, mm;dn-throttling hole diameter, mm;E-orifice plate thickness, mm;e-sharp edge thickness, mmFigure 1 Schematic diagram of orifice plate and pressure port structure
5.6 Power measurement
JB/T8941.2—1999
5.6.1 Use a torque meter to directly measure the input power of the blower; or indirectly determine the input power of the blower by measuring the output power of the motor and multiplying it by the transmission efficiency.
5.6.2 The range of the torque element of the precision torque meter should not be greater than 3 times the measured value. After the test, the torque meter and the torque element should be calibrated at the same temperature as the test or at the test site. Take a set of readings for increasing and decreasing loads respectively, and note that the load should not decrease when reading the readings during the increase of loads; the load should not increase when reading the readings during the decrease of loads. The power is calculated based on the average value of the readings during the increase and decrease of loads determined during the calibration period. If the torque difference between the increase and decrease of loads exceeds 1%, the torque meter fails. 5.6.3 The input electrical power should be measured and then multiplied by the efficiency of the motor to determine the output power of the motor. For three-phase motors, the two-wattmeter method or other methods with equal accuracy should be used, and the efficiency of the motor must be calibrated. The accuracy of the instrument should not be less than that specified in Table 3.
Ammeter
Voltmeter
Wattmeter
Mutual inductor
Power factor meter
Accuracy level
The range of ammeter and voltmeter should not be greater than 3 times of the measured value. The rated current and voltage of wattmeter should not be higher than 1.4 times of the measured value. 5.6.4 In addition to reliable data, the data in Table 4 is allowed to be used as the basic data of transmission efficiency. Table 4
Transmission mode
Coupling
5.7 Vibration measurement
Measured in accordance with the provisions of GB/T11347.
5.8 Noise measurement
Measured in accordance with the provisions of GB/T2888.
5.9 Other measurements
5.9.1 Bearing temperature
Transmission efficiency
When the blower is running under the specified load, after the temperature rise is stable, measure the surface temperature of the bearing or the vicinity of the bearing. 5.9.2 Lubricating oil temperature
When the blower is running under the specified load, after the temperature rise is stable, measure the temperature of the lubricating oil or the surface temperature at the oil level of the oil tank. 5.10 Calibration of instruments
Original records of calibration should be kept before the test.
For those main instruments whose calibration values are prone to change due to use in the test, calibration should be carried out again after the test. If the change during instrument calibration exceeds the range allowed by the instrument grade, the test is not recognized. 6 Test methods
6.1 The test is divided into type test and factory test according to the provisions of JB/T8941.1. The type test items are: temperature, pressure, volume flow, speed, shaft power, volume specific energy, vibration, noise and operating conditions. The delivery test items are: temperature, pressure, volume flow, speed, vibration and operating conditions.
6.1.1 The type test shall be carried out at more than 5 measuring points including the specified exhaust pressure, and the factory test shall be carried out at the specified exhaust pressure.
JB/T8941.2-1999
The test conditions shall be as close to the specified conditions as possible and reasonably possible, and the deviation from the specified conditions shall not exceed the limits of Table 5. Table 5 Maximum deviation from the specified value and maximum fluctuation relative to the average value Measurement parameters
Suction pressure
Suction temperature
Exhaust pressure
Orifice temperature
Orifice pressure difference
Maximum allowable deviation
Not specified
Not specified
Type test: ±4%
Factory test: -5%～～+10%
Not specified
Not specified
The maximum allowable fluctuation range between a group of readings and the average value is ±1%
During the test, the operation should be carried out according to the instruction manual. The lubricant, cooling water and their supply should not exceed the provisions of the instruction manual 6.1.3
6.1.4 Before taking the reading, the blower should run for a long enough time to ensure the stability of the operating conditions and at the same time ensure that the instrument readings do not change systematically during the test. If it is unavoidable that some individual readings are too large, the number of readings should be increased to ensure the accuracy of the item. 6.1.5 A sufficient number of readings should be taken under each load to indicate that a stable operating condition has been achieved. The number of readings and the interval time should be appropriately selected to ensure the required accuracy. 6.1.6 For factory tests, the blower should be operated continuously at the specified speed and pressure for not less than 2 hours, and the temperature of each part should be measured after the temperature rise stabilizes.
6.1.7 After the test, the blower and test equipment should be checked. If any fault that affects the test results is found, the test should be repeated after the fault is eliminated. 6.2 Test apparatus
6.2.1 See Figures 2, 3 and 4 for the test apparatus.6.2.2 Pipeline configuration
6.2.2.1 The positive pressure blower exhaust port or the negative pressure blower inlet port may use a tapered pipe (conical convergence angle less than 30°) or a gradually expanding pipe (conical divergence angle less than 14°), and the ratio of the cross-sectional area at both ends shall be between 0.7 and 1.3. When the exhaust port is at the top or bottom, an equal diameter elbow may be used, and the radius of curvature shall be greater than or equal to the pipe diameter. Blower
Filter
Prime mover
Pressure regulating valve
Connecting pipe
Positive pressure blower test device
Pressure regulating valve
Flow measuring device
Connecting pipe
Blower
Prime mover
Negative pressure blower test device
Flow measuring device
Filter
Blower
Prime mover
JB/T8941.2—1999
Pressure regulating valve
Connecting pipe
Figure 4 Group blower test device
Flow measuring device
6.2.2.2 The structure of the positive pressure blower exhaust pressure or negative pressure blower intake pressure port can adopt the structure shown in Figure 5 or other types, but must meet the requirements of Table 5. An annular chamber is welded at the static pressure port on the outer wall of the test pipe. The number of static pressure measurement points on the same section outside the annular chamber is 2, and the phase angle between the two measurement points is 90°. On the same section of the test pipe, 4 holes are evenly distributed along the circumference. The center line of the hole is perpendicular to the pipe wall, with a diameter of 2 to 6 mm. The interface with the test pipe, especially the inner wall, should be smooth and free of burrs. Annular chamber
Test pipe
6.2.2.3 The length from the blower exhaust port to the pressure regulating valve shall not be less than 4D. 6.2.2.4 The flow measurement device is shown in Figures 6 and 7. 6.2.2.5 The pressure regulating valve should be selected in a form with the smallest outlet bias flow as much as possible. Pressure regulating valve
Connecting pipe
≥I1D,
Grid flow regulator
Figure 6 is used for positive pressure blower measurement
6. 2. 2. 6
\(800~020)
Grid flow regulator see Figure 8
e = (0. 250 ~0. 083) D,
JB/T8941.2--1999
Pressure regulating valve
Used for negative pressure blower measurement
Figure 8 Grid flow regulator
6.3 Reading arrangement
Connecting pipe
6.3.1 Before making the final calculation, carefully check whether the recorded data is consistent with the operating conditions. The fluctuation of the readings in one test shall not exceed the limit specified in Table 5.
6.3.2 All readings used in any test should be continuous. 6.3.3 A group of readings with excessive fluctuations can but only the readings at the beginning or end of the test can be discarded. All data in a reading should be read simultaneously as much as possible.
6.4 Calculation of test results
6.4.1 General
6.4.1.1 Except for flow measurement, the arithmetic mean of the readings used should be used to calculate the test results. 6.4.1.2 The gas flow rate measured at the state of the measuring device should be converted to the standard suction position state to obtain the actual volume flow rate.
6.4.1.3 The test conditions will never be strictly consistent with the specified conditions. Therefore, before comparing the test results with the specified values, the volume flow rate and power should be corrected.
6.4.2 Calculation method
6.4.2.1 The gas constant of humid air is calculated according to formula (1): R 287.1/(1— 0.378 epws/ph)
6.4.2.2 The air flow density at the standard suction position is calculated according to formula (2): 463
JB/T 8941.2—1999
Pr = P1,/(RT,)
Note: When the blower is dispersed in the atmosphere test, p1=po, Ti=T. 6.4.2.3 The density of the gas upstream of the orifice throttling device is calculated according to formula (3): Pup = Pup.a/(RT..p)
6.4.2.4 The actual volume flow is calculated according to formula (4): Q =
6.4.2.5 The theoretical volume flow is calculated according to formula (5): aed,(2Appup)1/2/p
The volumetric efficiency is calculated according to formula (6):
6. 4. 2. 6
n=（Qa./Qth）×100
The volumetric specific energy is calculated according to formula (7):
6.4.3 Correction for specified operating conditions
6.4.3.1 The speed correction factor K is calculated according to formula (8): K, = n./n
The gas constant correction factor K2 is calculated according to formula (9): K2 (R./R)1/2
6.4.3.3 Pressure ratio correction factor K: calculated according to formula (10): K [(1)/(Yr - 1)71/2
1 For single-stage blower, = pa/p1.
2 For two-stage blower, it is the pressure ratio of the first-stage Roots blower. 6.4.3.4 The correction coefficient K for the inhaled gas temperature is calculated according to formula (11): K, - (T1../Ti.R)1/2
6.4.3.5 The corrected actual volume flow is calculated according to formula (12): Qacvrorr = K, X Qih -- (Qth.R - Qac.R)K,K,K,6. 4. 3. 6
The corrected shaft power is calculated according to formula (13): Ns.cor - K,N.
The corrected volumetric efficiency is calculated according to formula (14): v.corr = 1 - (1 - Nv.R)K,K,K,/K6.4.3.8 The corrected volumetric specific energy is calculated according to formula (15): Wv.corr Wv.RR/nv.cor
6.4.4 Test results
（2）
（3）
.（4）
（5）
（6）
+（12）
（13)
（ 14 ）
·（15)
The corrected data shall be summarized as the test results. When performance curves are required, the performance curves of Roots blowers shall be drawn with pressure as the abscissa and volume flow, shaft power, volumetric efficiency and volumetric specific energy as the ordinates. 7 Comparison of test results with specified values
The test results corrected in accordance with 6.4.3 shall be compared with the specified performance: comparison of the corrected power consumption with the specified power consumption, including volumetric specific energy; - comparison of the corrected volumetric flow with the volumetric flow guaranteed at the specified pressure. 464
8 Test report
JB/T 8941.2—1999
After the test is completed, a test report should be drawn up to record the test process and results. The test report should include the following: a) The time and place of the test and the name of the person in charge and other participants. b) The following technical data:
The model, specification, manufacturer and manufacturing time of the blower, a brief description of the operating data, accessories and its drive device and other characteristics (cooling and lubrication system, etc.).
The model, specification, manufacturer and manufacturing time of the drive device, especially the technical data necessary to determine the specified performance. c) The process plan and a simple diagram of the test device indicating the location of the measuring points, the instrument model and the calibration record. d) Point out the abnormal conditions recorded during the test. e) Calculation formulas, results and necessary charts. f) Comparison of actual performance with the specified value. Conclusion on whether the specified value is met. 465
Flow coefficient α
JB/T 8941.2—1999
Appendix A
(Appendix to the standard)
Flow coefficient and expansion coefficient
When ReD≥105~2×10°β≥0.05~0.64, D≥50～~1000mm, the flow coefficient α of the angle-connected orifice plate shall be taken according to Figure A1 or calculated according to Formula A1):
α= c/(1- β*)
In the formula, c=0.5959+0.0312p2.10.18403*+0.0029p2.5(106/Rep)0.75Rep is the Reynolds number, calculated according to Formula (A2): Ren = vD./u
Where: -
Average velocity of air in the test pipe, m/s; -Kinematic viscosity of air, see Table A1.
0. 050. 10
0. 150. 20
Kinematic viscosity
0.350.400.450.50
Flow coefficient
β2=(da/D,)2
.（A1)2--1999
Pressure regulating valve
When used for negative pressure blower measurement
Figure 8 Grid flow regulator
6.3 Reading arrangement
Connecting pipe
6.3.1 Before making the final calculation, the recorded data should be carefully checked to see if they are consistent with the operating conditions. The fluctuation of the readings in a test shall not exceed the limit specified in Table 5.
6.3.2 All readings used in any test should be continuous. 6.3.3 If there is a group of readings with excessive fluctuations, the readings at the beginning or end of the test can be discarded, but only. All data in a reading should be read at the same time as much as possible.
6.4 Calculation of test results
6.4.1 General
6.4.1.1 Except for flow measurement, the arithmetic mean of the readings used should be used to calculate the test results. 6.4.1.2 The gas flow rate measured by the measuring device at the state at that position should be converted into the state of the standard suction position to obtain the actual volume flow rate.
6.4.1.3 The test conditions will never be strictly consistent with the specified conditions. Therefore, before comparing the test results with the specified values, the volume flow rate and power should be corrected.
6.4.2 Calculation method
6.4.2.1 The gas constant of humid air is calculated according to formula (1): R 287.1/(1— 0.378 epws/ph)
6.4.2.2 The air flow density at the standard suction position is calculated according to formula (2): 463
JB/T 8941.2—1999
Pr = P1,/(RT,)
Note: When the blower is tested in the open atmosphere, p1=po, Ti=T. 6.4.2.3 The density of the gas upstream of the orifice throttling device is calculated according to formula (3): Pup = Pup.a/(RT..p)
6.4.2.4 The actual volume flow is calculated according to formula (4): Q =
6.4.2.5 The theoretical volume flow is calculated according to formula (5): aed,(2Appup)1/2/p
The volumetric efficiency is calculated according to formula (6):
6. 4. 2. 6
n=（Qa./Qth）×100
The volumetric specific energy is calculated according to formula (7):
6.4.3 Correction for specified operating conditions
6.4.3.1 The speed correction factor K is calculated according to formula (8): K, = n./n
The gas constant correction factor K2 is calculated according to formula (9): K2 (R./R)1/2
6.4.3.3 Pressure ratio correction factor K: calculated according to formula (10): K [(1)/(Yr - 1)71/2
1 For single-stage blower, = pa/p1.
2 For two-stage blower, it is the pressure ratio of the first-stage Roots blower. 6.4.3.4 The correction coefficient K for the inhaled gas temperature is calculated according to formula (11): K, - (T1../Ti.R)1/2
6.4.3.5 The corrected actual volume flow is calculated according to formula (12): Qacvrorr = K, X Qih -- (Qth.R - Qac.R)K,K,K,6. 4. 3. 6
The corrected shaft power is calculated according to formula (13): Ns.cor - K,N.
The corrected volumetric efficiency is calculated according to formula (14): v.corr = 1 - (1 - Nv.R)K,K,K,/K6.4.3.8 The corrected volumetric specific energy is calculated according to formula (15): Wv.corr Wv.RR/nv.cor
6.4.4 Test results
（2）
（3）
.（4）
（5）
（6）
+（12）
（13)
（ 14 ）
·（15)
The corrected data shall be summarized as the test results. When performance curves are required, the performance curves of Roots blowers shall be drawn with pressure as the abscissa and volume flow, shaft power, volumetric efficiency and volumetric specific energy as the ordinates. 7 Comparison of test results with specified values
The test results corrected in accordance with 6.4.3 shall be compared with the specified performance: comparison of the corrected power consumption with the specified power consumption, including volumetric specific energy; - comparison of the corrected volumetric flow with the volumetric flow guaranteed at the specified pressure. 464
8 Test report
JB/T 8941.2—1999
After the test is completed, a test report should be drawn up to record the test process and results. The test report should include the following: a) The time and place of the test and the name of the person in charge and other participants. b) The following technical data:
The model, specification, manufacturer and manufacturing time of the blower, a brief description of the operating data, accessories and its drive device and other characteristics (cooling and lubrication system, etc.).
The model, specification, manufacturer and manufacturing time of the drive device, especially the technical data necessary to determine the specified performance. c) The process plan and a simple diagram of the test device indicating the location of the measuring points, the instrument model and the calibration record. d) Point out the abnormal conditions recorded during the test. e) Calculation formulas, results and necessary charts. f) Comparison of actual performance with the specified value. Conclusion on whether the specified value is met. 465
Flow coefficient α
JB/T 8941.2—1999
Appendix A
(Appendix to the standard)
Flow coefficient and expansion coefficient
When ReD≥105~2×10°β≥0.05~0.64, D≥50～~1000mm, the flow coefficient α of the angle-connected orifice plate shall be taken according to Figure A1 or calculated according to Formula A1):
α= c/(1- β*)
In the formula, c=0.5959+0.0312p2.10.18403*+0.0029p2.5(106/Rep)0.75Rep is the Reynolds number, calculated according to Formula (A2): Ren = vD./u
Where: -
Average velocity of air in the test pipe, m/s; -Kinematic viscosity of air, see Table A1.
0. 050. 10
0. 150. 20
Kinematic viscosity
0.350.400.450.50
Flow coefficient
β2=(da/D,)2
.（A1)2--1999
Pressure regulating valve
When used for negative pressure blower measurement
Figure 8 Grid flow regulator
6.3 Reading arrangement
Connecting pipe
6.3.1 Before making the final calculation, the recorded data should be carefully checked to see if they are consistent with the operating conditions. The fluctuation of the readings in a test shall not exceed the limit specified in Table 5.
6.3.2 All readings used in any test should be continuous. 6.3.3 If there is a group of readings with excessive fluctuations, the readings at the beginning or end of the test can be discarded, but only. All data in a reading should be read at the same time as much as possible.
6.4 Calculation of test results
6.4.1 General
6.4.1.1 Except for flow measurement, the arithmetic mean of the readings used should be used to calculate the test results. 6.4.1.2 The gas flow rate measured by the measuring device at the state at that position should be converted into the state of the standard suction position to obtain the actual volume flow rate.
6.4.1.3 The test conditions will never be strictly consistent with the specified conditions. Therefore, before comparing the test results with the specified values, the volume flow rate and power should be corrected.
6.4.2 Calculation method
6.4.2.1 The gas constant of humid air is calculated according to formula (1): R 287.1/(1— 0.378 epws/ph)
6.4.2.2 The air flow density at the standard suction position is calculated according to formula (2): 463
JB/T 8941.2—1999
Pr = P1,/(RT,)
Note: When the blower is tested in the open atmosphere, p1=po, Ti=T. 6.4.2.3 The density of the gas upstream of the orifice throttling device is calculated according to formula (3): Pup = Pup.a/(RT..p)
6.4.2.4 The actual volume flow is calculated according to formula (4): Q =
6.4.2.5 The theoretical volume flow is calculated according to formula (5): aed,(2Appup)1/2/p
The volumetric efficiency is calculated according to formula (6):
6. 4. 2. 6
n=（Qa./Qth）×100
The volumetric specific energy is calculated according to formula (7):
6.4.3 Correction for specified operating conditions
6.4.3.1 The speed correction factor K is calculated according to formula (8): K, = n./n
The gas constant correction factor K2 is calculated according to formula (9): K2 (R./R)1/2
6.4.3.3 Pressure ratio correction factor K: calculated according to formula (10): K [(1)/(Yr - 1)71/2
1 For single-stage blower, = pa/p1.
2 For two-stage blower, it is the pressure ratio of the first-stage Roots blower. 6.4.3.4 The correction coefficient K for the inhaled gas temperature is calculated according to formula (11): K, - (T1../Ti.R)1/2
6.4.3.5 The corrected actual volume flow is calculated according to formula (12): Qacvrorr = K, X Qih -- (Qth.R - Qac.R)K,K,K,6. 4. 3. 6
The corrected shaft power is calculated according to formula (13): Ns.cor - K,N.
The corrected volumetric efficiency is calculated according to formula (14): v.corr = 1 - (1 - Nv.R)K,K,K,/K6.4.3.8 The corrected volumetric specific energy is calculated according to formula (15): Wv.corr Wv.RR/nv.cor
6.4.4 Test results
（2）
（3）
.（4）
（5）
（6）
+（12）
（13)
（ 14 ）
·（15)
The corrected data shall be summarized as the test results. When performance curves are required, the performance curves of Roots blowers shall be drawn with pressure as the abscissa and volume flow, shaft power, volumetric efficiency and volumetric specific energy as the ordinates. 7 Comparison of test results with specified values
The test results corrected in accordance with 6.4.3 shall be compared with the specified performance: comparison of the corrected power consumption with the specified power consumption, including volumetric specific energy; - comparison of the corrected volumetric flow with the volumetric flow guaranteed at the specified pressure. 464
8 Test report
JB/T 8941.2—1999
After the test is completed, a test report should be drawn up to record the test process and results. The test report should include the following: a) The time and place of the test and the name of the person in charge and other participants. b) The following technical data:
The model, specification, manufacturer and manufacturing time of the blower, a brief description of the operating data, accessories and its drive device and other characteristics (cooling and lubrication system, etc.).
The model, specification, manufacturer and manufacturing time of the drive device, especially the technical data necessary to determine the specified performance. c) The process plan and a simple diagram of the test device indicating the location of the measuring points, the instrument model and the calibration record. d) Point out the abnormal conditions recorded during the test. e) Calculation formulas, results and necessary charts. f) Comparison of actual performance with the specified value. Conclusion on whether the specified value is met. 465
Flow coefficient α
JB/T 8941.2—1999
Appendix A
(Appendix to the standard)
Flow coefficient and expansion coefficient
When ReD≥105~2×10°β≥0.05~0.64, D≥50～~1000mm, the flow coefficient α of the angle-connected orifice plate shall be taken according to Figure A1 or calculated according to Formula A1):
α= c/(1- β*)
In the formula, c=0.5959+0.0312p2.10.18403*+0.0029p2.5(106/Rep)0.75Rep is the Reynolds number, calculated according to Formula (A2): Ren = vD./u
Where: -
Average velocity of air in the test pipe, m/s; -Kinematic viscosity of air, see Table A1.
0. 050. 10
0. 150. 20
Kinematic viscosity
0.350.400.450.50
Flow coefficient
β2=(da/D,)2
.（A1)/Qth）×100
The volume ratio can be calculated according to formula (7):
6.4.3 Correction for specified working conditions
6.4.3.1 The speed correction factor K is calculated according to formula (8): K, = n./n
The gas constant correction factor K2 is calculated according to formula (9): K2 (R./R)1/2
6.4.3.3 The pressure ratio correction factor K is calculated according to formula (10): K [(1)/(Yr - 1)71/2
1For single-stage blowers, = pa/p1.
2For two-stage blowers, it is the pressure ratio of the first-stage Roots blower. 6.4.3.4 The correction coefficient K for the inhaled gas temperature is calculated according to formula (11): K, - (T1../Ti.R)1/2
6.4.3.5 The corrected actual volume flow is calculated according to formula (12): Qacvrorr = K, X Qih -- (Qth.R - Qac.R)K,K,K,6. 4. 3. 6
The corrected shaft power is calculated according to formula (13): Ns.cor - K,N.
The corrected volumetric efficiency is calculated according to formula (14): v.corr = 1 - (1 - Nv.R)K,K,K,/K6.4.3.8 The corrected volumetric specific energy is calculated according to formula (15): Wv.corr Wv.RR/nv.cor
6.4.4 Test results
（2）
（3）
.（4）
（5）
（6）
+（12）
（13)
（ 14 ）
·（15)
The corrected data shall be summarized as the test results. When performance curves are required, the performance curves of Roots blowers shall be drawn with pressure as the abscissa and volume flow, shaft power, volumetric efficiency and volumetric specific energy as the ordinates. 7 Comparison of test results with specified values
The test results corrected in accordance with 6.4.3 shall be compared with the specified performance: comparison of the corrected power consumption with the specified power consumption, including volumetric specific energy; - comparison of the corrected volumetric flow with the volumetric flow guaranteed at the specified pressure. 464
8 Test report
JB/T 8941.2—1999
After the test is completed, a test report should be drawn up to record the test process and results. The test report should include the following: a) The time and place of the test and the name of the person in charge and other participants. b) The following technical data:
The model, specification, manufacturer and manufacturing time of the blower, a brief description of the operating data, accessories and its drive device and other characteristics (cooling and lubrication system, etc.).
The model, specification, manufacturer and manufacturing time of the drive device, especially the technical data necessary to determine the specified performance. c) The process plan and a simple diagram of the test device indicating the location of the measuring points, the instrument model and the calibration record. d) Point out the abnormal conditions recorded during the test. e) Calculation formulas, results and necessary charts. f) Comparison of actual performance with the specified value. Conclusion on whether the specified value is met. 465
Flow coefficient α
JB/T 8941.2—1999
Appendix A
(Appendix to the standard)
Flow coefficient and expansion coefficient
When ReD≥105~2×10°β≥0.05~0.64, D≥50～~1000mm, the flow coefficient α of the angle-connected orifice plate shall be taken according to Figure A1 or calculated according to Formula A1):
α= c/(1- β*)
In the formula, c=0.5959+0.0312p2.10.18403*+0.0029p2.5(106/Rep)0.75Rep is the Reynolds number, calculated according to Formula (A2): Ren = vD./u
Where: -
Average velocity of air in the test pipe, m/s; -Kinematic viscosity of air, see Table A1.
0. 050. 10
0. 150. 20
Kinematic viscosity
0.350.400.450.50
Flow coefficientwww.bzxz.net
β2=(da/D,)2
.（A1)/Qth）×100
The volume ratio can be calculated according to formula (7):
6.4.3 Correction for specified working conditions
6.4.3.1 The speed correction factor K is calculated according to formula (8): K, = n./n
The gas constant correction factor K2 is calculated according to formula (9): K2 (R./R)1/2
6.4.3.3 The pressure ratio correction factor K is calculated according to formula (10): K [(1)/(Yr - 1)71/2
1For single-stage blowers, = pa/p1.
2For two-stage blowers, it is the pressure ratio of the first-stage Roots blower. 6.4.3.4 The correction coefficient K for the inhaled gas temperature is calculated according to formula (11): K, - (T1../Ti.R)1/2
6.4.3.5 The corrected actual volume flow is calculated according to formula (12): Qacvrorr = K, X Qih -- (Qth.R - Qac.R)K,K,K,6. 4. 3. 6
The corrected shaft power is calculated according to formula (13): Ns.cor - K,N.
The corrected volumetric efficiency is calculated according to formula (14): v.corr = 1 - (1 - Nv.R)K,K,K,/K6.4.3.8 The corrected volumetric specific energy is calculated according to formula (15): Wv.corr Wv.RR/nv.cor
6.4.4 Test results
（2）
（3）
.（4）
（5）
（6）
+（12）
（13)
（ 14 ）
·（15)
The corrected data shall be summarized as the test results. When performance curves are required, the performance curves of Roots blowers shall be drawn with pressure as the abscissa and volume flow, shaft power, volumetric efficiency and volumetric specific energy as the ordinates. 7 Comparison of test results with specified values
The test results corrected in accordance with 6.4.3 shall be compared with the specified performance: comparison of the corrected power consumption with the specified power consumption, including volumetric specific energy; - comparison of the corrected volumetric flow with the volumetric flow guaranteed at the specified pressure. 464
8 Test report
JB/T 8941.2—1999
After the test is completed, a test report should be drawn up to record the test process and results. The test report should include the following: a) The time and place of the test and the name of the person in charge and other participants. b) The following technical data:
The model, specification, manufacturer and manufacturing time of the blower, a brief description of the operating data, accessories and its drive device and other characteristics (cooling and lubrication system, etc.).
The model, specification, manufacturer and manufacturing time of the drive device, especially the technical data necessary to determine the specified performance. c) The process plan and a simple diagram of the test device indicating the location of the measuring points, the instrument model and the calibration record. d) Point out the abnormal conditions recorded during the test. e) Calculation formulas, results and necessary charts. f) Comparison of actual performance with the specified value. Conclusion on whether the specified value is met. 465
Flow coefficient α
JB/T 8941.2—1999
Appendix A
(Appendix to the standard)
Flow coefficient and expansion coefficient
When ReD≥105~2×10°β≥0.05~0.64, D≥50～~1000mm, the flow coefficient α of the angle-connected orifice plate shall be taken according to Figure A1 or calculated according to Formula A1):
α= c/(1- β*)
In the formula, c=0.5959+0.0312p2.10.18403*+0.0029p2.5(106/Rep)0.75Rep is the Reynolds number, calculated according to Formula (A2): Ren = vD./u
Where: -
Average velocity of air in the test pipe, m/s; -Kinematic viscosity of air, see Table A1.
0. 050. 10
0. 150. 20
Kinematic viscosity
0.350.400.450.50
Flow coefficient
β2=(da/D,)2
.（A1)
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