Safety regulations for painting process ventilation and purification
1 the general
1.1 in order to prevent the harm of harmful substances, make the working conditions of painting meet the requirements of safety and health, ensure the safety and health of workers, protect the environment and promote production, this regulation is hereby formulated.
1.2 this specification is applicable to the ventilation and purification of painting process. For ventilation and purification of outdoor painting process for large components such as Bridges, buildings, large storage tanks and ships, please refer to this code.
1.3 for the painting process of releasing hazardous substances, comprehensive prevention and treatment measures such as ventilation and purification and personal protection should be taken.
1.4 the concentration of harmful substances in the air of the painting workshop shall not exceed the maximum allowable concentration specified in tj36-79 "hygienic standards for design of industrial enterprises".
1.5 to prevent the indoor diffusion of harmful substances such as gas, smoke and dust, local exhaust shall be adopted first. When it is impossible to use local exhaust or local exhaust is still not up to the requirements of tj36-79, comprehensive ventilation shall be adopted.
1.6 pollutants containing harmful gases, smoke, dust and other pollutants discharged by the exhaust system shall be purified, recycled or comprehensively utilized to discharge into the atmosphere when they affect the air quality of the environment around the workshop or the living area of nearby residents, so as to meet the requirements of tj36-79.
1.7 the fan shall be turned on before starting the painting operation, and then the spraying equipment shall be started. When the ventilation system stops or fails, the automatic control device should immediately cut off the power supply and signal the operator. When the work is finished, the spraying equipment should be shut down first, and then the fan should be shut down.
1.8 industrial enterprises may choose to adopt activated carbon adsorption, catalytic combustion, thermal combustion or liquid absorption and other chemical measures enumerated in this code according to the process conditions and pollution conditions, so as to ensure that the air quality in and around the workshop conforms to the requirements of articles 1.4 and 1.6 of this code.
1.9 in the ventilation and purification equipment system, the concentration of flammable and explosive gases and vapors shall not exceed 25% of the lower limit of explosion.
2.1 the local exhaust system for painting must be equipped with a device to remove the paint mist.
2.2 the exhaust hood with local exhaust shall meet the following requirements:
A. The exhaust hood shall be located at the source of hazardous substances;
B. The suction direction of the exhaust hood shall be such that hazardous substances do not pass through the operator's breathing belt;
C. The form and size of the exhaust hood shall be determined by the volatility and specific gravity of the emitted organic gases and vapors and the method of painting.
2.3 for the process equipment with substances distributed in the painting workshop, if the airtight or semi-airtight device cannot be used, the side suction hood, umbrella hood, blowing suction type exhaust hood or slot side exhaust hood can be used respectively according to the production conditions and ventilation effect.
2.4 the mechanical exhaust system in the painting workshop that often emits harmful gas shall be equipped with a bypass exhaust pipe so as to continue to discharge harmful gas when the ventilation equipment stops working.
2.5 when painting and other work in a closed space, mobile air supply and exhaust devices should be set. The air flow of harmful gases must avoid passing through the operator's breathing belt.
The paint spraying room is ventilated
3.1 painting shall be done in the painting room with mechanical ventilation device.
3.2 airflow distribution in the paint spraying room should be reasonable, and dead Angle and eddy current should not be formed.
3.3 the side draft painting room of middle and small workpieces shall be equipped with a device for rotating the workpiece, so as to facilitate the operator to spray all aspects of the workpiece without being affected by the spray of paint mist.
3.4 use the bottom exhaust air supply at the top of the painting room, spray tall workpiece, should use the height tool, the height should ensure that the operator's breathing belt is not contaminated by harmful substances.
3.5 spray with groove workpiece, should use long handle spray gun, so that the operator's breathing belt is not in the area where the paint mist occurs.
3.6 it is suggested to use the following table for the control wind speed of the painting room:
Control the wind speed in the paint chamber
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Operating conditions airflow │ │ interference control wind speed design value
(artifacts in completely indoor) │ │ m/s m/s
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Automatic electrostatic painting or airless spray painting forget │ │ large spray room 0.25
(no indoor │ │ medium and small spray room 0.50
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Hand painted │ │ large spray room 0.50 0.25
│ │ medium and small spray room 0.75
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Hand painted │ │ large spray room below 0.75 0.50
│ │ medium and small spray room 1.00
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Note: (1) control wind speed refers to the cross section wind speed of airflow in the painting room.
(2) spray car, truck paint room for large; Spraying water pump, fan, etc. for the spray room, small.
(3) interfering air flow refers to the air flow generated by the draught or other air supply and exhaust system that affects the control of wind speed.
3.7 when lead or chromium coating is applied, the control wind speed of the paint chamber shall be 1.0-1.2m/s.
4 ventilation of powder spraying room
4.1 powder spraying shall be carried out in a special powder spraying room and operated by the operator outdoors.
4.2 the dusting chamber should be closed or semi-closed, and must be equipped with dust purification and recovery device. The dust removal efficiency of the recovery device shall ensure that it does not pollute the surrounding environment.
4.3 the discharge port of the dust purification and recovery device shall adopt measures to prevent dust from flying, so as to ensure that the maximum allowable concentration of dust in the air in the operating environment conforms to the provisions of TJ 36-79.
4.4 as far as possible, the air inlet of the exhaust pipe of the powder spraying room should be consistent with the flow direction when the dust is dispersed.
4.5 the recommended wind speed at the opening of the powder chamber is 0.3-0.6m/s.
4.6 the workshop with a powder spraying room must be separated and enclosed from other equipment systems to prevent interference with air flow.
4.7 pressure relief devices shall be installed in the powder spraying room and dust purification and recovery device, and the pressure relief outlet shall be directed to the roof or the direction that no one passes through.
4.8 the inner wall of the powder spraying chamber and conveying duct shall be smooth, the conveying pipe shall be inclined and have sufficient wind beam velocity to avoid dust accumulation.
4.9 spray chamber, dust purification and recovery device, electrostatic powder gun and piping system should be checked and cleaned frequently.
5.1 when the painting process and equipment are not fixed and local exhaust air cannot be used, comprehensive exhaust air shall be used.
5.2 under special circumstances, large area painting operation, due to the wide distribution, should use organized comprehensive exhaust, so that the operator is not in the air pollution.
5.3 local exhaust shall be used in the coating deployment room. If local exhaust cannot be used due to limited conditions, comprehensive exhaust can be used.
5.4 when vapors of several solvents (benzene and its homologues, alcohols and acetic esters) are released into the air at the same time, the total ventilation volume shall be calculated according to the sum of the air volume required for each gas to be diluted to the maximum allowable depth.
5.5 the amount of harmful gas dispersed into the painting workshop can be determined according to the number of air changes in the room according to the measured data or empirical data of similar workshops when no process design data or calculation method is available.
5.6 when harmful gas and steam are discharged from the overall exhaust system of the painting workshop, the air inlet should be set in the area with the highest concentration of harmful substances. The flow direction of the air distribution in the overall exhaust system shall avoid the flow of hazardous substances through the operator's breathing belt.
Air supply system
6.1 the painting workshop with local exhaust or overall exhaust shall be naturally ventilated; Mechanical air supply system should be set up when the natural air supply cannot make the harmful substances in indoor air conform to the maximum allowable concentration or the room temperature is too low to affect the production.
6.2 if the painting workshop is in a dusty environment, air filtration and purification devices should be set in the mechanical air supply system.
6.3 the content of harmful substances in the air sent into the workshop by the mechanical air supply system shall not exceed 30% of the maximum allowable concentration stipulated in TJ 36-79.
6.4 when the environmental sanitation around the painting workshop is poor, the air supply should be slightly greater than the air exhaust to maintain the indoor micro-positive pressure. When the indoor concentration of harmful substances is higher than the adjacent room, the air supply should be slightly less than the exhaust air, so that the indoor maintain micro negative pressure.
6.5 the position of the inlet of the mechanical air supply system shall meet the following requirements:
A. should be located in a clean outdoor area;
B. It shall be set in the downwind direction of the exhaust outlet with the minimum frequency of wind direction all year round, and it shall be lower than 2m of the exhaust outlet;
C. The bottom of the air inlet should not be less than 2m away from the outdoor floor;
D. If the air inlet and outlet must be located at the same height above the roof, the horizontal distance shall not be less than 10 times of the pipe diameter and shall not be less than 10m;
E. When harmful substances in the workshop are discharged through the skylight, air inlet should be avoided on the roof of the workshop.
6.6 the inlet air of the mechanical air supply system shall be sent to the working area or the working place where the workers often stay.
6.7 reasonably organize the intake and exhaust air flow to prevent the air containing hazardous substances from flowing through the operating area containing no or only a small amount of hazardous substances.
7 ventilation ducts
7.1 the air supply and exhaust system of the painting workshop shall be clearly designed; The air inlet and the air outlet should set the barbed wire, and should direct to the outdoor impossible to have the spark fall place; The moving parts such as the regulating valve on the air pipe shall be made of materials that are impact-proof.
7.2 lightning protection measures of exhaust duct shall comply with GBJ 57-83 "lightning protection design code for buildings".
7.3 ventilation pipes used in various processes in the painting workshop shall not be connected with ventilation pipes used in other processes or chimney flue conveying combustible materials.
7.4 for the ventilation system that needs to adjust the air volume, the air volume measurement hole shall be set at the section where the air flow in the air pipe is relatively stable.
7.5 to observe the air temperature in the duct of the high-temperature exhaust system, a temperature measuring hole and a thermometer shall be set on the duct.
7.6 inlet and exhaust devices and inlet and exhaust pipes shall adopt effective measures to prevent pollutant deposition and shall be cleaned regularly.
7.7 insulation, heat preservation or antifreeze measures shall be taken when the air temperature conveyed by ventilation and purification equipment and pipelines is significantly increased or decreased, or may be frozen.
7.8 inspection holes must be set for exhaust pipes with a diameter of less than 300mm and laid every 300mm or so, but the distance between inspection holes on air pipes with a large diameter can be increased. The inspection hole shall be located at the bend of the pipe.
7.9 the ducts of the ventilation system must be set up strictly to prevent air leakage, and should be disassembled for easy cleaning.
7.10 air duct support shall be firm and reliable, and the support shall be able to bear the dynamic load of the air duct in its own weight.
7.11 conveying high temperature gas duct, when temperature is 80-200 ℃, its appearance with the structure of the flammable structures and equipment should be kept more than 0.5 m distance, the distance from refractory structure and equipment should be kept more than 0.25 m.
7.12 the exhaust duct and pipe wall temperature higher than 80 ℃ transport inflammable and explosive gas, steam and dust should be not less than 1 m, horizontal distance between the hot gas duct should be laid in the transportation of low temperature gas duct. Transmission of above 80 ℃ gas or flammable and explosive gas pipeline application of non-combustible material.
7.13 electric wires, gas pipes, heat pipes and pipes for the delivery of liquid fuel shall not be installed on the wall of the ventilation pipe or through the air pipe.
7.14 when ducts pass through a flammable roof or wall, they must be blocked with a refractory or emptied around the ducts where they pass.
8.1 the fan room of the painting workshop shall be separated from other rooms and shall not be used for other purposes.
8.2 the air supply and air exhaust equipment of the painting workshop shall not be arranged in the same ventilator room. Exhaust equipment shall not be arranged in the same ventilator room with other ventilation equipment used in rooms without explosion risk.
8.3 when air volume of ventilator is determined, air leakage volume of air duct and equipment shall be added. General air supply and exhaust system additional 5-10%; Dust removal system plus 10-15%.
8.4 when determining the ventilation fan's air pressure, the added value of pressure loss shall be taken into account at the same time. General air supply and exhaust system additional 10-15%; Dust removal system plus 15-20%.
8.5 industrial enterprises should choose low-noise machines or adopt sound insulation, muffler and other measures. The noise level in the workplace should comply with GB 87-85 "design code for noise control in industrial enterprises".
Activated carbon adsorption method
9.1 purification of room temperature organic gas discharged from painting can be carried out by fixed bed activated carbon adsorption method and steam desorption method.
9.2 activated carbon is used as the adsorbent. For example, the thickness of the adsorption bed is 0.5-1m, and the velocity of the empty tower is 0.2-0.3m/s, and the highest is not more than 0.5m/s.
9.3 should be set in the adsorber thermometer, temperature alarm and fire water pipe, immediately report to the police when activated carbon layer temperature of 150 ℃, close the fan and adsorber import valve. If the temperature continues to rise, you should open the water valve, water cooling.
9.4 pressure gauge and pressure relief pipe (or safety valve) shall be set at the top of the adsorber.
9.5 a gas sampling tube shall be set at the outlet of the air outlet of the adsorber, and the concentration of the gas shall be measured regularly. When the harmful gas leaks, the adsorber shall be stopped and desorption shall be carried out.
9.6 a pressure gauge shall be installed on the air duct at the air outlet of each adsorber to measure and adjust the air discharge through each adsorber.
9.7 a filter for removing impurities and dust shall be installed in front of the fan, and a pressure gauge shall be installed for the filter. When the resistance of the filter exceeds the design resistance, it shall be cleaned immediately.
9.8 a bypass exhaust pipe should be set before the filter. When the adsorption purification system fails or the work ends, the exhaust pipe valve should be opened immediately to temporarily empty the harmful gas to prevent poisoning or explosion accidents due to excessive concentration.
9.9 the flame arrester must be installed after the filter. Safety exhaust pipe must be set up in oil-water separator, oil storage tank, gas-liquid separator and other equipment.
9.10 the temperature shall be set on the steam pipe for desorption