Methods for measuring meteorological conditions in the hot work environment
Some standard content:
National Standard of the People's Republic of China
Methods for measuring meteorological conditions in the hot work environment
GB 934 89
This standard adopts the main measurement items of physical factors of hot environment proposed by the International Organization for Standardization (IS0/D1S7726, 1982). 1 Subject content and applicable scope
This standard specifies the items, time, place and methods for measuring meteorological conditions in hot work environment. This standard is applicable to hot work production sites with heat sources. 2 Reference standards
JJG204 Ventilated dry-bulb and wet-bulb thermometer
JJG210 Meteorological mercury barometer
JJG273 Empty box barometer
3 Terminology
3.1 Meteorological conditions of hot working environment Meteorological conditions of hot working environment mcnt refers to the air temperature, humidity, wind speed and thermal radiation in the high-temperature working environment, and also includes air pressure when necessary. 3.2 Air temperatureutc
The temperature of the air in the working environment. Expressed in degrees Celsius. 3.3 Humidity
The moisture content in the air of the working environment. Expressed as the ratio of the water vapor partial pressure in the air to the water vapor partial pressure of the air at the same temperature (dead), that is, relative humidity. 3.4 Air velocity
The flow speed of the air in the working environment. Expressed in meters per second (m/s). 3.5 Heat radiation intensity Heat radiation intensity The radiation intensity of infrared rays and some visible lines in the working environment, expressed in the number of joules of heat radiation energy received per square centimeter per minute (J/mmmin) (1J=0.2388cal) a. Directional heat radiation intensity Direction heat radiation intensity The heat radiation intensity of a heat source in a specific direction. b. Average heat radiation intensity Average heat radiation intensity The average value of the common heat radiation intensity of multiple heat sources to a certain point. 3.6 Atmasphere
The pressure of the air in the working environment, expressed in Pa (Pa) (1Pa=0. 007 5 mmHg) Approved by the State Administration of Technical Supervision on March 22, 1989, and implemented on October 1, 1989
4 Measurement Items
GB 934-89
The measurement items for meteorological conditions in high-temperature working environments include: air temperature, air humidity, wind speed and thermal radiation intensity. All items should be measured at the same time and at the same location. If necessary, such as high mountains, high pressure, underground, etc., the air pressure can also be measured. The WBGT value is not marked as a difficult item, and is listed in Appendix C (reference number) for reference. 5 Measurement Time
5.1 Measure in the hottest month in summer, and measure continuously for 3~5 days each time. Record the original data and calculate the average value and the highest value. 5. 2 When the heat source of the working environment is stable, measure once every half an hour after starting work, once during work, and once before leaving get off work. If production is stopped within the specified time, the measurement time can be advanced or postponed. 5.3 When the heat source of the working environment is unstable and the production process changes periodically, it should be measured once each hour after the start of production and half an hour before the end of production. During the production process, it should be measured 3 to 4 times as the production process changes. 6 Measurement location
6.1 Select the operator's operating location, frequent stopover location and temporary rest area, 6- 2 The measurement height is 1.5 m for vertical operation and 1.1 m for sitting operation. 6.3 Measurement location:
6.3.1 The air temperature, air humidity, wind speed and average heat radiation intensity are measured at the operator's operating position. 6.3.2 The directional heat radiation intensity is measured at the operator's operating position: 1: equivalent to the operator's head, chest and legs at three different heights.
6.4 In principle, local cooling measures should be taken during the measurement. If it is necessary to understand the local cooling effect and the actual heat stress of the operator, local cooling measures can be taken continuously.
6.5 Outdoor meteorological conditions should be measured at the same time. Outdoor measurements should be made in an open place upwind of the vehicle, avoiding direct sunlight. 7 Measurement method
. Steam temperature and air humidity measurement method
7.1.1 The measuring instrument uses a ventilated condensation bulb thermometer, preferably a mercury thermometer, and is expressed in Celsius. The measuring range is -15～50℃, and the reading scale is 0.2℃.
7.1.2 Before use, check whether the mercury columns of the thermometer are connected, and check whether the readings of the two thermometers are consistent. The total difference does not exceed 0.1℃. 7.1.3 The bulb of the bulb thermometer is wrapped with a sleeve-type absorbent cotton wool. If absorbent cotton gauze is used, it should be wrapped with two layers. The gauze should not exceed one-fourth of the circumference of the bulb. The gauze should be kept clean. Before use, add steam to a rubber ball to make it fully wet. When it is wet, the instrument should not fall over, and pay attention to prevent the wet gauze from blocking the sleeve. 7.1.4 When there is a heat source on the ground at the measuring point, regardless of the intensity of the heat radiation, a reflective half-board material with a diameter of 20 cm should be used to block it 10 cm below the air inlet.
7.1.5 Place the ventilated wet-bulb thermometer at the measuring point, wind it up, and read the reading after 3 minutes. When reading, keep your eyes level with the top of the mercury column, read the decimal first, then the integer, and read the reading accurately to 0.1.1-6 After the measurement is completed, wait until the wind of the instrument stops rotating: the receiver can be put away. 7.1.7 Check the special relative humidity calculation table to determine the condensation value (Appendix A), and check the instrument error correction value for correction. 7.1.8 When the reading exceeds the leakage of the special table, the formula can be used to calculate the humidity. The formula is as follows: R relative humidity, :
partial pressure of water vapor in air, Pa;
.++.++.
GB 93 4-89
+ partial pressure of saturated water vapor in air at global temperature, Pa (Appendix A). The calculation formula of A in formula (1) is:
Wherein, P is the partial pressure of saturated water vapor in the air at wet-bulb temperature, Pa: - = wet-bulb thermometer coefficient at different wind speeds, 1/(Appendix A) - dry-bulb thermometer degree, C;
is -- wet-bulb thermometer degree.;
n -- atmospheric pressure at the time of measurement, Pa.
7.2 Method for measuring wind speed
7.2.1 Select anemometer according to wind speed
When the wind speed is less than 1ms, a hot-bulb electric anemometer, a cup anemometer or a wing anemometer can be used. When the wind speed is less than 1m/s, a hot-bulb electric anemometer or a wing anemometer can be used. 7.2.2 Use of hot-bulb anemometer
7.2.2.1 The hot-bulb anemometer can directly read the instantaneous wind speed and is suitable for wind speeds of 0.05-~30m/s. 7.2.2.2 Before measuring, calibrate the mechanical zero point, adjust the full scale and zero point, and read the value once every 0.5 min for 3 times in a row, and take the average value. 7.2.3 Use of cup anemometer 7.2.3.1 Cup anemometer is suitable for wind speeds of 1~10 m/s. 7.2.3.2 When measuring, record the initial reading, face the wind direction (make sure your body is not affected by the airflow), let the wind hand rotate freely, and then start the anemometer and stopwatch at the same time, and measure for 100 s. Record the final reading and calculate according to formula (3): wind speed (m/s) = final reading (m), initial reading (m) × 100 (s) 7.2. 4. Use of wing anemometer
7.2.4.1 The wing anemometer is suitable for wind speeds of 0.5 to 10 m/s. (3
7.2.4.2 The wing anemometer has a directional arc. When measuring, face the wind direction (so that the body does not hinder the airflow). The rotation axis of the wing should be consistent with the wind direction. When the counting disk returns, the start switch of the anemometer and the stopwatch should be activated. Measure 100 s. Divide the reading by 100 to get the wind speed (m/s). 7.2.5 Calibration
The readings of the above three anemometers should be calibrated according to the calibration curve provided by the instrument. 7.3 Determination of thermal radiation intensity
The thermal radiation in the working environment can come from one direction or from several directions. Therefore, there is a distinction between fixed thermal radiation intensity and average thermal radiation intensity.
7.3.1 Determination of fixed thermal radiation intensity
7.3.1.1 Directional thermal radiation intensity can be determined using a unidirectional thermocouple radiation calorimeter. 7.3.1.2 When measuring, face the sensing surface to the radiation source, open the front cover for 3~5s, and read the stable value of the meter (J/cm2min). 7.3.2 Determination of semi-average thermal radiation intensity
7.3.2.1 The average thermal radiation intensity is determined using a black ball thermometer. 7.3.2.2. The surface of the black-globe thermometer is covered with soot (kerosene plus rosin). 7.3.2.3. The black-globe thermometer is placed at the measuring position and the temperature reading is read after 15 minutes. 7.3.2.4. The air temperature and wind speed are measured simultaneously.
7.3.2.5 Calculate the average heat radiation intensity according to formula (4): na = 1.17(±273) + 2.45 (4)]-600100
Where: Hm
Average heat radiation intensity, J/em\-min:
——black ball temperature, ℃
Gas overflow, ℃,
\speed, m/s.
4 Method for determination of vapor pressure
7.4.1 Use of cup-shaped mercury gas bed gauge
GB 934-89
7.4.1.1 The pressure gauge should be hung vertically on the inner wall to avoid swinging and direct sunlight, and there should be no strong heat source around. 7.4.1.2 During the measurement, first adjust the adjustment screw at the bottom of the instrument so that the mercury surface in the mercury cup just touches the tip of the ivory pointer. Move the vernier scale so that the scale line at its zenith is tangent to the mercury column. At this time, the scale reading on the fixed scale pointed by the scale line at the zero point of the vernier scale is the integer of the air pressure. Then find the scale line on the vernier scale that matches the scale line of the fixed scale. The reading of the scale line on the vernier scale is the first decimal place of the air pressure. The two readings are added together to get the millimeter column (mmHg) of the atmospheric pressure at that time: according to 1mmIIg=133.322Pa, convert the atmospheric pressure unit into Pascals (Pa). 7.4.1.3 When it is necessary to measure the air pressure accurately, the air temperature reading attached to the barometer must also be recorded, and the air temperature and instrument error correction must be made according to the instruction manual of each barometer.
7.4.2 Use of the empty box manometer
7.4.2.1 Calibrate with a mercury barometer before use. 7.4.2.2 When in use, tap the barometer to compensate for the error of mechanical friction. 7.4.2.3 After the pointer stabilizes, record the reading. It should be accurate to 67Pa (i.e. 0.5mmHg). 8 Recording of meteorological conditions measurement results
The meteorological conditions measurement results must be recorded on a special record sheet (see the table below). Meteorological conditions measurement record form for high temperature working environmentUnit name:
Workshop name:
Measurement period:
Operation name
(or heat source condition)
Ventilation wet bulb
Thermometer
Weather condition: cloudy
Weather forecast, maximum temperature during the day:
Minimum temperature in the morning:
Average thermal radiation
J/cmz.mEn
One-way thermal radiation intensity
J/cm2.min
Record:
GD 9 3 4 8 9
Common number tables
(supplement)www.bzxz.net
Air relative humidity calculation table (calculated according to the ventilation thermometer and hygrometer reading when the wind speed is 4m/s), see Table A1. A1
Table of partial pressure of saturated water vapor, see Table A2. A2
Dry-bulb and wet-bulb thermometer coefficients at different wind speeds, see Table A3. A3
13, Core
GB 93489
Table Al Table of relative air humidity calculation (calculated according to the ventilation temperature and humidity meter reading at a wind speed of 4m/s) Wet
1. 55. 0! 5. 5
6. 06. 57.07.58-08.59. 0 9. 5 |10.010. 511. 011. 5|12. 0 relative
GB 93 4 8 9
Continued Table A1 Air relative humidity calculation table (calculated according to the ventilation temperature and humidity meter reading when the wind speed is 4m/s) Sheng
12.51311.15.56.167.8.8.99.52.2021.21.22.22.2.023 relative
7 ! 81
GB 934
Continued Table A1 Air relative humidity calculation table (calculated according to the ventilation temperature and humidity meter reading at a wind speed of 4m/s) Display
10.511.0:11.512.012.513.013.514.014.515.015.516.016.517.017.518.018.519.019.5 Phase
GB 93 4 89
Continued Clothes A1 Air relative humidity calculation (calculated according to the ventilation temperature and humidity meter reading at a wind speed of 4m/s) Instrument
20.0.20.521.0 21.5;22.022-523-023.524.024.525.025.5.26.026.527.027.528.028.529.0
— 12
Water vapor partial pressure
265-311
286-642
610, 181
GB 934 89
Table A2 Saturated water vapor partial pressure table
1 12- 0
Water vapor pressure
Table A3 Dry and wet bulb thermometer coefficients at different wind speeds
— 29. 0
Water vapor partial pressure
12333.618
15737.320
19915.640
25003.208
38543.390
47342.642
GB 934-89
Appendix B
Line diagram of average radiation intensity
(Supplement)
In order to simplify the calculation, the line diagram (see Figure B1) can be used to find the average radiation intensity. The method of use is as follows: Example: The measurement result is: t, = 88 ℃, t, -37 C + = 0. ≤ m/a. Calculate the average radiation intensity. Solution: . . =51℃ Take 51℃ on line 1, take 0.5m/s on line II, connect and extend and intersect with I, take 88℃ on line IV, connect the points on II and I, the point where this line intersects with V is the average radiation intensity 8.8J/cm\·min. 0
Globe temperature and empty temperature
Undrawn radiation intensity
(J/umt-min)
Figure B Flat and radiation intensity line solution diagram
Appendix C
Wet bulb globe temperature (WBGT) index determination method (reference)
Xizhu plate
In high temperature working environment, the wet bulb globe temperature (WBGT) index is often measured as a comprehensive evaluation index of heat stress of workers.L ct instrument
C1.1 Natural wet-bulb thermometer (instrument for outdoor measurement)
Wrap gauze around the bulb of the mercury thermometer. The gauze should cover the bulb and the length of the bulb, and there should be 2.5cm between the bottom of the bulb and the water surface. The wet gauze is still exposed to the air. 1. Soak the outer end of the gauze strip in a small cup with distilled water. C1. 3 Black ball thermometer
C2 Measurement steps
C2.1 The gauze of the natural wet-bulb thermometer should be completely condensed with distilled water 30m before measurement. When the air is too dry, add water to moisten the gauze strip regularly.
C2.2 Place the natural wet-bulb thermometer and the black ball thermometer vertically at the measurement point for outdoor measurement. A dry-bulb thermometer is also required and placed in the same way. However, the bulb should be shielded to avoid the influence of sunlight or other infrared sources. The condensation bulb thermometer should not be shielded. It is best to fix the three temperatures on the same bracket L.
C2.3 After about 15 minutes, the natural wet bulb thermometer and the black ball thermometer are stable, and the readings of the natural wet bulb temperature (cn), black ball temperature {) and ball temperature (t) are read respectively.
C3 Calculation formula of WBGT
WBGT =- 0. 7 tnwb + 0.2 t, + 0. I t. If it is indoors, the formula is
WBGT - 0. 7 tuh + 0. 3
If the environmental conditions vary greatly or the heat stress levels caused by the workers going back and forth to work are different, the time-weighted average formula is used:
WBGTtwa
(WRGT) + (WBGT)t +-- + (WRGT)t++t+ .+ +f.
WBGT,-WBGT measured at the first location or position; WBGT:-WBGT measured at the second location or position; WBGT.
ti,tg...-t,
WBGT measured at the nth location or position;
The person is at the first,2……n time spent at a location or post. Appendix D
Instructions for the correct use of the standard
(reference)
D1 This standard is applicable to the determination of meteorological conditions in high-temperature working environments, including high temperature, high humidity and strong radiation environments. It can also be used as a reference for the determination of meteorological conditions in non-commercial temperature working environments.
D2 This standard proposes basic instruments. They are all instruments that are currently widely used in China, easy to buy, easy to use, and have full box effects. They can not only meet the needs of determination, but also be convenient for various units to adopt. Other related instruments that can achieve the return sample effect can also be used. D3 All instruments must be kept in good condition when leaving the factory. The ventilation dry and wet bulb meter should comply with the technical requirements of JJG201, and the inspection cycle is 3 years. The meteorological mercury gas meter should comply with the technical requirements of JJG273, and the inspection cycle is 3 years. The empty box barometer should comply with the technical requirements of JJC210, and the inspection cycle is 3 pieces. When it expires, it should be contacted with the metering unit or meteorological department for calibration. D4 The operating procedures must be followed when using the instrument.
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