GB 18562-2001 Occupational exposure limits for calcium cyanamide (lime nitrogen) in workplace air

This standard specifies the maximum permissible concentration of calcium cyanamide in workplace air, the time-weighted average permissible concentration (8h), and the monitoring and testing methods. This standard applies to all types of industrial enterprises that produce and use calcium cyanamide (lime nitrogen). GB 18562-2001 Occupational exposure limits for calcium cyanamide (lime nitrogen) in workplace air GB18562-2001 Standard download decompression password: www.bzxz.net

GB18562-2001
This standard is formulated for the first time based on experimental research, on-site labor hygiene survey, occupational population survey data, and reference to relevant foreign literature and corresponding standards. It is a hygienic standard used for workplace environmental monitoring and health supervision. This standard shall be implemented from May 1, 2002. Appendix A of this standard is the appendix of the standard.
This standard is proposed by the Ministry of Health of the People's Republic of China. The drafting units of this standard are: Occupational Safety and Health Research Institute of the Ministry of Chemical Industry, Juhua Group Corporation, Fujian Sanming Chemical General Plant, Jilin Chemical Industry Company Calcium Carbide Plant, Jiangxi Gannan Chemical Plant.
The semi-drafting persons of this standard are: Tu Zhangling, Yaping, Tingqing, Fu Guisheng, Liang Baozong. The technical unit of this standard is the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, which is responsible for the interpretation. 733
National Standard of the People's Republic of China
Occupational exposure limit for calcium cyanamide in the air of workplace
GB18562--2001
This standard specifies the maximum permissible concentration, time-weighted average permissible concentration (8h) and monitoring and inspection methods of calcium cyanamide in the air of workplace.
This standard is applicable to various industrial enterprises that produce and use calcium cyanamide (lime nitrogen). Hygiene requirements
The maximum permissible concentration of calcium cyanamide in the air of workplace is 3mg/m3, and the time-weighted average permissible concentration (8h) is 1mg/m3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt the spectrophotometer method, see Appendix A (Appendix to the standard). Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on December 4, 2001 734
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Implementation on May 1, 2002
A1 Principle
GB 185622001
Appendix A
(Standard Appendix)
Spectrophotometric determination of calcium fluoride in workshop air Calcium cyanamide in the air is collected with glass fiber filter paper. Calcium cyanamide is decomposed in concentrated sulfuric acid. Ammonia reacts with Nessler's reagent to produce yellow. The colorimetric quantification is carried out at a wavelength of 420 nm. A2 Instruments
A2.1 Glass fiber filter paper. www.bzxz.net
A2.2 Small plastic sampling clip.
A2.3 Dust sampling clip.
A2.4 Small dust sampler: flow rate 5~20 L/min. A2.5 Air sampler: flow rate 0~~2 L./min, A2.6 Round bottom flask: 100mL.
A2.7 Stoppered graduated test tube: 50mL and 10ml. A2.8 Spectrophotometer: 10 mm colorimetric cup. .A3 Reagents
The water used in this method is ammonia-free distilled water.
A3.1 Sulfuric acid: P2O—1.84 g/mL. A3.2 Sulfuric acid solution: 0.005mal/L
A3.3 Sodium hydroxide solution: 58g/L.
A3.4 Nessler's reagent: Dissolve 17 g mercuric chloride in 300 mL water, and 35 g potassium iodide in 100 mL water, and drop the mercuric chloride solution into the potassium iodide solution until a red precipitate is formed. Then add 200% sodium hydroxide solution and the remaining sodium chloride solution, shake and store in a brown bottle in a dark place for several days, take out the supernatant, put it in another brown bottle, plug it with a rubber stopper, and store it away from light. A3.5 Ammonia standard solution: weigh 0.3879 g of ammonium sulfate dried at 80°C for 1 h, dissolve it in sulfuric acid solution, and make up to 100 mL; this solution is a stock solution containing 1.0 mg ammonia in 1 mL. Take 2.0 mL of the stock solution in a 100 mL volumetric flask and dilute it to the mark with sulfuric acid solution. This solution is a standard solution containing 20 g ammonia in 1 mL. A4 Sampling
A4.1 Fixed-point sampling: Put the dust sampling center equipped with glass fiber filter paper and collect 15 ml of air sample at the sampling point at a flow rate of 15 L/min.
A4.2 Individual sampling: Wear a small plastic sampling clip with glass fiber paper on the upper chest of the sampling object, and collect air samples for 1 hour at a flow rate of 1L/min.
A5 Analysis steps
A5.1 Control test: Bring the sampling clip with filter paper to the site, and except for not collecting air samples, perform the same operation as the sample. It serves as a blank control for the sample.
A5.2 Sample treatment: Put the sampled filter paper into a bottom flask, add 20 mL sulfuric acid, heat it on an electric stove until it slowly boils, then heat it until it smokes, and continue heating for 5 minutes; remove it from the electric stove and cool it to room temperature; use sulfuric acid solution to quantitatively transfer the residual wave into a 50 mL 735
GB18562—2001
scaled test tube, and dilute to the scale, and shake well. If there are residues such as graphite, filter with quantitative filter paper; add 2.0ml of the filtrate to a 1mt stoppered scale test arm, dilute to the scale with sulfuric acid solution, shake well and then measure. A5.3 Preparation of standard curve: Take 7 10nL stoppered scale test tubes and prepare the standard series according to Table A1. Table A1 Preparation of ammonia standard series
Standard solution, mL
Sulfuric acid solution. l
Ammonia content·zone
Add 0.5mL Nessler's reagent to each standard tube, spread evenly, let stand for 5 minutes, and measure the absorbance at a wavelength of 420nm. Measure each concentration 3 times, and draw a standard curve with the average value of the measured absorbance against the corresponding nitrogen content (g): A5.4 Sample determination: Use the same operating conditions solution and blank control solution to determine the standard tube, subtract the absorbance value of the blank control from the measured sample absorbance value, and check the standard curve to obtain the nitrogen content (ug). A6 Calculation
A6. 1 Convert the sampling volume into the volume V under standard conditions according to formula (A1). V,=VX
273 --t
Where: V——converted sampling volume under standard conditions, L; V——sampling volume, L;
pressure——atmospheric pressure at the sampling site, kPa; air temperature at the sampling site, ℃.
A6.2 Calculate the concentration of calcium cyanamide in the air according to formula (A2).
25Xm×2.35
Where:
——calcium cyanamide in the air, mg/m
25——dilution multiple of sample solution;
——the amount of calcium cyanamide in the sample measured, m
V. -Converted to the sampling volume under standard conditions, L; 2.35…-The coefficient of converting nitrogen acid to calcium cyanamide. A7 Description
A7.1 The detection limit of this method is 2g/mL of hydrogen, and the minimum detection concentration is 0.235mg/m3 of calcium cyanamide (sampled in 225I. air); the standard deviation is 5.2%.
A7.2 The sampling efficiency of this method is 98%~105%, and the digestion recovery rate is 99%. A7.3 The sample can be stored at room temperature for at least 7 days. A7,4 This method determines ammonia. Any compound that can generate ammonia under the reaction conditions of this method may interfere with this method. 736
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