This standard specifies the maximum permissible concentration of toluene diisocyanate (TDI) in the air of a workshop and its monitoring and inspection methods. This standard is applicable to newly built, rebuilt and expanded industrial enterprises. GB 16193-1996 Hygienic standard for toluene diisocyanate (TDI) in the air of a workshop GB16193-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Health standard for toluene diisocyanate in the air of workplace
1 Subject content and scope of application
GB16193-1996wwW.bzxz.Net
This standard specifies the maximum allowable concentration of toluene diisocyanate (TDI) in the air of workplace and its monitoring and inspection methods. This standard applies to newly built, rebuilt and expanded industrial enterprises. For existing industrial enterprises with pollution hazards, they should also actively take effective measures to gradually meet the relevant provisions of this standard. 2 Hygiene requirements
The maximum allowable concentration of TDI in the air of workplace is 0.20mg/m3. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt the hydrochloric acid ethylenediamine colorimetric method, see Appendix A (supplement). 4 Supervision and implementation
Health and epidemic prevention agencies at all levels are responsible for supervising the implementation of this standard. Approved by the State Administration of Technical Supervision on April 3, 1996, and implemented on September 1, 1996
A1 Principle
GB16193—1996
Appendix A
Colorimetric determination of ethylenediamine hydrochloride
(Supplement)
Toluene diisocyanate is hydrolyzed to produce the corresponding aromatic amine, which is diazotized with sodium nitrite and then coupled with naphthylethylenediamine hydrochloride to produce a purple-red color, which is quantitatively determined by colorimetry.
The detection limit of this method is 0.6μg/5mL.
A2 Apparatus
Porous glass plate absorption tube.
A2.2 Vacuum pump.
Flowmeter, 0～1L/min.
A2.4 Colorimetric tube, 10mL.
A2.5 Spectrophotometer.
A3 Reagents
Absorption solution: Mix 25mL hydrochloric acid with 500mL water, add 250mL dimethylformamide, dilute with water to 1L, prepare before use.
A3.2 Sodium nitrite-sodium bromide solution, weigh 3g sodium nitrite and 5g sodium bromide, dissolve in about 80mL water and dilute to 100mL. A3.3 10% ammonium sulfamate solution.
A3.4 1% naphthylethylenediamine hydrochloride solution.
A3.5 Standard solution: Add 5mL dimethylformamide to a 25mL volumetric flask, weigh accurately, add 1-2 drops of toluene diisocyanate, weigh accurately again, the difference between the two weights is the weight of toluene diisocyanate, then dilute to the scale with dimethylformamide. Calculate the content of toluene diisocyanate in each milliliter of solution, and then dilute it with dimethylformamide to make a 1mL solution containing 100 μg toluene diisocyanate. Take 5.0mL of the above solution in a 50mL volumetric flask, add 7.50mL of dimethylformamide and 1.25mL of hydrochloric acid, mix well and dilute with water to the scale to make a standard solution of 1ml=10 μg toluene diisocyanate. A4 Sampling
Connect two porous glass plate absorption tubes each containing 10mL of absorption liquid in series, and extract 20L of air at a speed of 0.5L/min. A5 Analysis steps
Wash the inner wall of the air inlet pipe 3 times with the absorption liquid in the absorption tube. Then, measure 5mL of sample solution from each absorption tube and put it into the colorimetric tube respectively, and prepare the standard tube according to Table A1. Table Al
Standard solution, ml
Absorption solution, mL
Toluene diisocyanate content·ug
Preparation of toluene diisocyanate standard tube
GB 16193—1996
Add 0.2mL of sodium nitrite-sodium bromide solution to each sample tube and standard tube, mix, let stand for 2min, then add 0.2mL of 10% ammonium sulfamate solution, shake vigorously, let stand for 2min after the bubbles disappear, add 1mL of 1% naphthylethylenediamine hydrochloride solution, mix thoroughly and let stand for 15min, and quantify colorimetrically at a wavelength of 560nm. A6 Calculation
2(Ci +C2)
Where: X-
Concentration of toluene diisocyanate in the air, mg/m; Ci.C2
V. —Sampling volume under standard conditions, L. A7 Explanation
A7.1 The absorption solution should be prepared just before use, because after long-term storage, the hydrochloric acid in it will gradually lose its acidity due to the action of dimethylformamide. (Al)
A7.2 When the concentration of toluene diisocyanate is 2, 4, 6, 8, 10μg/5mL, the coefficient of variation is 3.8%, 1.9%, 1.0%, 1.0%, 0.8%, respectively.
Additional explanation:
This standard is proposed by the Ministry of Health of the People's Republic of China. This standard is drafted by the Gansu Provincial Health and Epidemic Prevention Station and the Gansu Provincial Institute of Labor Hygiene and Occupational Disease Prevention and Control. The main drafters of this standard are Zhou Hongci and Liu Jianye. The Ministry of Health has entrusted the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, to interpret this standard.
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