Third, adhere to the principle of honesty and trustworthiness, carry out occupational health technical services according to law, ensure that technical conclusions are scientific, objective and true, and bear legal responsibility for the occupational health technical reports issued.
Four, adhere to the concept of quality service, strengthen service awareness, strengthen self-construction, and constantly improve the ability and level of occupational health technical services.
Five, adhere to the market rules of fair competition, fulfill their duties, and consciously safeguard the image and reputation of the industry.
Six, adhere to clean practice, abide by professional ethics, undertake the obligation of confidentiality, and consciously resist unfair practice.
18. What are the key points of noise measurement?
Answer: The measurement should be carried out under normal production conditions.
Generally speaking, the microphone should wear a windshield. If the wind speed exceeds level 4, the measurement should be stopped (the experiment shows that the wind speed is? At 3m/s, whether wearing a hood has no obvious effect on the test results. When the wind speed reaches 4 and 5m/s, it is 7.5 and 16dB(C) higher without hood than with hood, respectively. 0.5 and 3.5 decibels (a). Therefore, when the wind speed is >: 3m/s, wear a hood, and stop measuring when the wind speed exceeds 5m/s).
When the relative temperature in the workplace exceeds 90%, a moisture-proof microphone should be used.
Stay away from the electromagnetic field and avoid interference (it can be eliminated by adjusting the direction of the microphone).
The battery can't be connected backwards. Take it out after use.
When loading and unloading the condenser microphone, the battery must be turned off.
This instrument should be calibrated regularly.
After measurement, the use of equipment shall be registered.
General production noise measurement should be carried out when the noise intensity in the workplace is greater than 80dB(A), and noise intensity below 78dB(A) is not considered as noise operation.
19. What are the main contents of the field survey before sampling?
(1) Types, quantity, purity, impurities and physical and chemical properties of raw and auxiliary materials, products, by-products and intermediate products used in the working process.
(2) The workflow includes the input mode of raw materials, production technology, heating temperature and time, production mode and the intact degree of production equipment, etc.
(3) The working conditions of workers, including the number of workers, the time in the workplace, the working methods, the degree, frequency and duration of exposure to harmful substances, etc.
(4) The generation and diffusion law, existing state and estimated concentration of harmful substances in the air of workplace.
(5) Hygienic and environmental conditions in the workplace, sanitary protection facilities and their use, personal protection facilities and their use, etc.
20. Combined with the actual work, talk about how your unit carries out laboratory quality control?
Laboratory quality control has the following methods:
(1) Determine the standard deviation of the blank batch and calculate the stable detection limit of the detection method;
(2) Recovery rate of sample addition: By measuring the recovery rate of added samples, find out the factors that can change the accuracy of the method without affecting the precision;
(3) Standard precision experiment: By comparing the intra-batch variation and inter-batch variation of standards (gas or solution, excluding blank) of different concentrations, the errors caused by standard preparation operation and experimental conditions are tested;
(4) Elution and desorption efficiency: through the experiments of elution and desorption efficiency at high, medium and low concentrations, the errors in the sample treatment process were detected;
(5) Use of reference materials: check the reliability of the standards (gas or solution) prepared by our laboratory, and compare them with the standards prepared by our laboratory by testing the quality control samples or evaluation standards uniformly distributed by the superior laboratory;
(6) Establish a control chart: use the control chart to constantly check the precision and accuracy of the detection method, so as to correct the changes caused by time at any time;
(7) Detection and evaluation of blank samples for quality control.
Third, the calculation problem
1. A certain type of work in a workshop works 5 days a week and 8 hours a day. According to the investigation, the workers' exposure to ethyl acetate (PC-TWA is 200mg/m3) is: 300 mg/m3 for 3 hours; 60 mg/m3, contact for 2 hours; 120 mg/m3 for 3 hours. According to the above situation, please analyze and judge whether the exposure level of workers in this type of work meets the health requirements, and ask the reasons.
Answer: (1) The concentration of ethyl acetate exposed to workers in this type of work per shift is:
CTWA =(c 1t 1+C2 T2+C3 T3)/8 =(300？ 3+60? 2+ 120? 3)? 8= 172.5 (mg/m3)
It is less than PC-TWA(200mg/m3), so the exposure level of this type of workers to ethyl acetate does not exceed that of occupational exposure limits, which meets the requirements.
2. Diluent for one workshop, with dosage of 3kg per hour. The main components of diluent are xylene 30%, ethyl acetate 50% and ethanol 20%, and the minimum air volume required for workshop air to meet the hygienic standard is calculated.
Serial number Chinese name occupational exposure limits (mg/m3)
MACPC-TWAPC-STEL
1. Xylene -50 100
2. Ethyl acetate -200300
3. Ethanol-
Answer: According to the calculation formula L = m/ys-y0;
Where: L-ventilation volume, m3/h;
M- the amount of harmful substances produced. Mg/hour;
YS—— occupational exposure limits specified in health standards; Mg/m3;
Y0—— the background concentration of the harmful substance in fresh air, mg/m3.
Xylene consumption m is: 3? 1000? 1000? 30% = 900000mg；
The consumption m of ethyl acetate is: 3? 1000? 1000? 50% = 1500000mg；
According to the actual production, occupational exposure limits selected the PC-TWA value, that is, YS (xylene) is 50mg/m3, YS (ethyl acetate) is 200mg/m3, and Y0? 0
l = 900000/50-0+ 1500000/200-0 = 18000+7500 = 25500 m3/h = 25500/3600
=7.08 m3/s
Therefore, the minimum air volume of workshop air meeting the hygienic standard is 7.08m3/s.
3. The following figure shows a local exhaust system, and the three local exhaust hoods have the same structure.
It is known that the total air volume of the system is L=2m3/s, and the static pressure at point A is Paj =-100pa; Static pressure at point b pbj =-150 pa; Static pressure at point c PCj=- 100Pa. Find out the exhaust volume of each exhaust hood.
A: According to the calculation formula Q =；;
Where: q-exhaust air volume of exhaust hood, m3/h;
F—— the measured cross-sectional area of the cover nozzle, m2;
Pj？ Determine the static pressure of the section, pa;
? —— density of gas in the pipe, kg/m3;
U-shaped flow coefficient is only related to the structure and shape of exhaust hood.
According to the known conditions, FA = FB = FC.
De: QA+QB+QC = 2
QA=QC
Therefore: QA = QC = 0.62m3/h;
QB = 0.76m3/hour.
Fourth, the essay questions
1. A portland cement factory needs to carry out pre-assessment of occupational hazards. As an evaluator, what should be done in the preparatory stage of pre-evaluation of occupational hazards? This paper expounds the main production process links of Portland cement plant and the identification of main occupational hazard factors in each link.
Answer: The main tasks in the preparation stage of the pre-assessment of occupational hazards are to accept the entrustment of the construction unit, collect and study relevant information, conduct preliminary investigation and analysis, prepare the pre-assessment plan and conduct technical audit, and determine the principles and key points of quality control.