This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of polymethyl polyphenyl polyisocyanates in the air of workshops and their monitoring and testing methods. This standard is applicable to various industrial enterprises that produce and use polymethyl polyphenyl polyisocyanates. GB 18533-2001 Occupational exposure limits for polymethyl polyphenyl polyisocyanates in the air of workshops GB18533-2001 Standard download decompression password: www.bzxz.net

GB18533—2001
This standard is formulated based on toxicological experiments, labor hygiene and epidemiological survey data, and with reference to foreign occupational exposure limits for isocyanate ester compounds. It is a hygienic standard for environmental monitoring and health supervision in the workplace. This standard will be implemented from May 1, 2002
The appendix A of this standard is the appendix of the standard.
This standard was proposed by the Ministry of Health of the People's Republic of China. The responsible drafting units of this standard are: the Ministry of Health's Marine Underwater Engineering Science Research Institute, the Labor and Personnel Bureau of China National Petroleum Corporation; the participating drafting units are: Shengli Youyou Administration Bureau Health and Epidemic Prevention Station. The main drafters of this standard are: Zhang Yaoran, Li Xin, Chen Mailuo, Zhao Changhong, Zhang Yanmeng, Qiao Dongliang, and Tian Guoxiong. This standard is entrusted to the Institute of Labor Health and Occupational Diseases of the Chinese Academy of Preventive Medicine for interpretation. 1 Scope
National Standard of the People's Republic of China
Occupational exposure limit for polymethylene polyphenyisocyanate (PMPPI) in the air of workplace GB 18533-2001
This standard specifies the maximum allowable concentration and time-weighted average allowable concentration of polymethylene polyphenyisocyanate (PMPPI) in the air of workplace and its monitoring and inspection methods.
This standard is applicable to various industrial enterprises that produce and use polymethylene polyphenyisocyanate. 2 Hygiene requirements
The maximum allowable concentration of polymethylene polyphenyisocyanate in workplace air is 0.5 mg/m3, and the time-weighted average allowable concentration is 0.3 mg/m3.
3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt spectrophotometry, 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 and implemented on May 1, 2002
A1 Principle
GB18533-2001
Appendix A
(Appendix to the standard)
Spectrophotometric determination of polymethyl polyisocyanate (PMPPI) in workshop air
The aromatic amine produced by the hydrolysis of PMPPI is diazotized with sodium nitrite and then coupled with ethylenediamine hydrochloride to produce a purple-red color, which is quantitatively measured by colorimetry. A2 Instruments
A2.1 Large bubble absorption tube or impact absorption tube. A2.2 Air sampler: flow range 0~2L/min. A2.3 Stoppered colorimetric tube: 25ml.
A2.4 Spectrophotometer. 1cm colorimetric cup.
A3 Reagents
The experimental water is distilled water.
A3. 1 Hydrochloric acid: 02n-1.15 g/mL.
A3.2 Acetic acid: P=1.05g/mL.bzxZ.net
A3.3 Absorption solution: add 12mL hydrochloric acid and 23mL acetic acid to about 6)mL water, dilute with water to 1000mL. A3.4 Hydrochloric acid solution (1.2mol/L): take 37mL hydrochloric acid, dilute with water to 1000ml.gA3.5 Acetic acid solution (0.6mol/L): take 34mL acetic acid, dilute with water to 100Uml.A3.6 Sodium nitrite-sodium bromide solution: weigh 3.0g sodium nitrite and 5.0g sodium bromide. Dissolve in 801L water, and then dilute to 100mL.
A3.7 Ammonium sulfamic acid solution: weigh 10g ammonium sulfamic acid, dissolve in water, and then dilute to 100mL. A3.8 Naphthylethylenediamine hydrochloride solution: weigh 0.1% naphthylethylenediamine hydrochloride, add 25mL water to dissolve, then add 1mL hydrochloric acid, and dilute with water to 100mL.
A3.9 Standard solution
Liquid A: weigh 0.5000g PMPPI. Dissolve in 660mL acetic acid, stir to dissolve and dilute with water to 1000mL, prepare liquid B in 15min, liquid B: take 10ml of liquid A into a 1000mL volumetric flask, add 27mL acetic acid and dilute with water to the mark. A4 Sampling
Use the absorption tube containing 10mL absorption liquid to extract 50L of air at a flow rate of 11./min. A5 Analysis steps
A5.1 Control test: Take the absorption arm containing 10ml absorption liquid to the site, except that the air is not collected, and the rest of the operation is the same as the sample as a blank control.
a5.2 Sample treatment: After deep sampling, wash the inner wall of the air intake pipe with the absorption liquid in the absorption tube for 3 times, pour the absorption liquid into the colorimetric tube, wash the absorption tube with about 5mL absorption liquid for 2~3 times, add this washing liquid into the colorimetric tube, and then dilute it to 15ml with the absorption liquid, scale, for determination. A5.3 Drawing of standard curve: Take 9 colorimetric tubes and prepare standard tubes according to Table A1. Add 0.5mL sodium nitrite-sodium bromide solution to each standard tube, mix and place at 90, add 1mL ammonium hydrosulfate solution, mix and place for 2min, add 1mL ethylenediamine hydrochloride solution, GB18533—2001
After mixing and placing for 5min, use a 1 cm colorimetric cup at a wavelength of 550nm, with the reagent empty (0 tube) as the reference for colorimetric determination, and plot the absorbance against the PMPPI content to draw a standard curve. Table Al
Hydrochloric acid solution, nl
Acetic acid solution, ml
Solution B, mL
PMPPI content + μ8
Preparation of PMPPI standard tube
A5.4Sample determination: According to the same operation steps as A5.3, the treated sample is measured. After the absorbance is subtracted from the blank control value, the PMPPT content is found from the standard curve.
A6Result calculation
A6-1Convert the sample volume into the volume under standard conditions according to formula (A1): V=VX
Volume under standard conditions, L;
V.--Sample volume, L.
t--Temperature, C.
Atmospheric pressure, kPa.
A6-2 Calculate the concentration of PMPPI in the workshop air according to formula (A2): 273
273 + t
Where: e—concentration of PMPPI in the workshop air, mg/m*; PMPPI content in the absorption tube, μg;
V—sample volume under standard conditions, I. A7 Explanation
(A1))
....(A2)
A7.1 The detection limit of this method is 2μg/15ml. The minimum detection concentration is 0.04mg/m (50L air). The measurement range is 2.5~40g/15mL. When the PMPPI concentration is 2.5, 5.0, 10.0, 30.0, and 40.0 g/15 ml, the coefficients of variation are 5.8%, 4.6%, 3.8%, 3.1%, and 2.8%, respectively.
A7.2 The samples can be stored for 1 day after sampling; there is no detectable change in absorbance within 60 minutes after the sample is fully colored.
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