This standard specifies the maximum permissible concentration of respirable cement dust in workshop air and its monitoring and inspection methods. This standard is applicable to cement plants and various enterprises using cement. GB 16238-1996 Hygienic standard for respirable cement dust in workshop air GB16238-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Health standard for respirable cement dust in the air of workplace Subject content and scope of application
GB16238—1996
This standard specifies the maximum permissible concentration of respirable cement dust in the air of the workplace and its monitoring and inspection methods. This standard applies to cement plants and various enterprises using cement. 2 Reference standards
GB5748 Determination of dust in workplace air 3 Terminology
Respirable cement dust: The aerodynamic diameter of the collected dust is below 7.07 aum, and the collection efficiency of dust with an aerodynamic diameter of 5μm is 50%.
Respirable dust samplers should have the following characteristics for separating particles: P=1-
Where: P transmittance,
D——dust aerodynamic diameter, um, D. --7. 07 μm.
4 Hygiene requirements
(D≤D.)
(D> D.)
The maximum permissible concentration of respirable cement dust with a free silicon dioxide content of less than 10% in the workshop air is 2 mg/m. 5 Monitoring and inspection methods
For the determination method of the concentration of respirable cement dust in the workshop air, see Appendix A (Supplement). Approved by the State Administration of Technical Supervision on April 3, 1996 550
Implemented on September 1, 1996
A1 Principle
GB16238—1996
Appendix A
Method for determination of respirable dust concentration
(Supplement)
Collect a certain volume of dust-laden air, pass it through a graded preselector, and retain the respirable dust on a filter membrane of known mass. The mass of respirable dust per unit volume of air is calculated from the increment of the filter membrane after dust collection (mg/m2). A2 Equipment
A2.1 Sampler: A respirable dust sampler that has passed the inspection of a unit designated or commissioned by the State Administration of Technical Supervision must be used. The separation performance of the sampling head for dust particles should meet the requirements of this standard, and the sampler should use a constant flow rate. When sampling in an operating environment with explosion-proof requirements, an explosion-proof respirable dust sampler is required. The air tightness of the sampling head shall meet the requirements of Appendix A (Supplement) of GB5748. A2.2 Filter membrane: Use perchloroethylene fiber filter membrane (dust filter membrane) with a diameter of 40mm. When perchloroethylene fiber filter membrane is not applicable (such as high temperature, organic solvents that can dissolve the filter membrane), glass fiber filter membrane can be used instead. A2.3 Gas flow meter: Use a 20L/min flow meter. The flow meter is calibrated once every six months with a soap film flow meter, a bell-type gas meter or a rotor flow meter with an accuracy of ±1%. If the flow meter is found to be obviously contaminated, it should be cleaned and calibrated in time. A2.4 Balance: Use an analytical balance with a sensitivity of 0.00001g. According to the requirements of the measurement department, it should be calibrated once a year. A2.5 Timer: Stopwatch or a timer equivalent to a stopwatch. A2.6 Dryer: Contains color-changing silica gel.
A2.7 Silicone oil: Methyl silicone oil with a viscosity of about 60,000. A3 Determination Procedure
A3.1 Preparation of filter membrane: Use tweezers to remove the backing paper on both sides of the filter membrane, place it on a balance and weigh it, record the initial mass, then put the filter membrane into the filter membrane holder, confirm that the filter membrane has no wrinkles or cracks, and put it into a numbered sample box for use. If you use an impact respirable dust sampler (TR dust sampler), you need to apply silicone oil or adhesive on the impact piece. When applying the adhesive, apply it evenly. The amount should not be too much, 5 to 8 mg is appropriate. After applying, weigh it on a balance, record the initial mass, and then put the impact piece number in a storage basin for use. A3.2 Setting up the sampler: Take out the prepared filter membrane holder and put it into the sampling head and tighten it. If you use a TR sampling head, put the impact piece into the sampling head and then tighten it. When sampling, the inlet of the sampling head should face the dusty airflow. If the production conditions are such that splashing mud or sand particles contaminate the sample, the inlet of the sampling head can be sideways to the dusty airflow. A3.3 Time to start sampling: For continuous dust-generating work points, sampling should be started 30 minutes after the start of the work. For discontinuous dust-generating work points, sampling should start when the workers are working.
A3.4 Sampling flow rate: During the entire sampling process, it must be maintained at 20L/min, and the flow rate should be stable to ensure that the respirable dust can meet the sampling performance required in this standard.
A3.5 The duration of sampling should be determined based on the estimated value of the dust concentration at the dust measurement point and the minimum value of the required dust increment on the filter membrane, but the sampling time should not be less than 10 minutes.
A3.6 The increment of respirable dust collected on the filter membrane should not be less than 0.5mg, but not more than 10mg. A3.7 Processing of samples after sampling: At the end of sampling, turn off the sampler switch and record the duration of sampling, sampling location, sample number, working conditions, etc. Then take out the filter membrane and impact piece that have collected respirable dust. Under normal circumstances, it does not need to be dried and can be directly placed on the balance for weighing and record its mass. If the relative humidity at the sampling site is above 90%, the filter membrane should be placed in a dryer for 2 hours and then weighed, and the measurement results should be recorded. Then, it should be placed in a dryer for 30 minutes and weighed again. If there are droplets on the filter membrane, it should be placed in a dryer for 12 hours and then weighed, and the results should be recorded. Then, it should be placed in a dryer for 2 hours and weighed again. When the difference in mass between two consecutive times does not exceed 0.1 mg, take the minimum value. wwW.bzxz.Net
A4 Calculation
Respirable dust concentration is calculated according to formula (A1): Where: R-
-Respirable dust concentration, mg/m~,
-Mass of the filter membrane before sampling, mg;
Mass of the filter membrane after sampling, mg;
tSampling time, min;
QSampling flow rate, L/min.
A5 Explanation
GB16238-1996
m2 - mi
+*(A1)
This method is the basic method for determining respirable dust. If other instruments or methods are used to determine the concentration of respirable dust, the sampling performance of the respirable dust must meet the requirements of this standard. Additional explanation:
This standard is proposed by the Ministry of Health of the People's Republic of China. This standard was drafted by the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine. The main drafters of this standard are Fu Shaochang, Cheng Yuhai, Liu Miao, Xu Jiaming and Fan Yanhua. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, which is the technical management unit entrusted by the Ministry of Health. 552
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