The dyeing chamber is a fairly clean and airtight room, which is necessary for the dyeing process of various objects and products. The operating conditions of such production suggest the presence of severe air pollution with vapors of dyes and solvents. To ensure the quality of work performed and the safety of the health of the operator, good ventilation is necessary in such a box.
Types of ventilation systems
Any supply and exhaust system for painting rooms should provide high-quality work in two modes: in the ventilation mode and in the drying mode. In ventilation mode:
- The supply ventilation of the spray booth should provide this room with purified and heated air up to 30 ° C.
- The hood should provide a uniform intake of air masses from the painting room, cleaning from contaminants and removing the cleaned air masses into the atmosphere.
In this mode, at least 40 times the air exchange should be provided. A much larger multiplicity can also be used so as not to exceed the MPC of toxic vapors of solvents used in painting. Moreover, the supply of fresh air flow should be carried out from the top of the painting room. The intake of air masses should be carried out from the bottom of the box along its entire perimeter.
In the drying mode, the ventilation system must supply filtered air heated to 60 °C to the room.
There are two main types of room ventilation for such enterprises:
- Supply, with mechanical impulse. The inlet purified air is supplied from the roof of the box, and the contaminated air enters the filter elements through the holes in the floor and is released into the environment under the action of natural draft.
- Mechanical, supply and exhaust. It differs from the supply only in that the exhaust ventilation of the spray booth is done with a mechanical impulse.
It should be noted that the performance of the supply fan must be higher than the capacity of the exhaust fan. Due to this, excess pressure is created in the room, at which dust and other mechanical impurities cannot enter it through natural cracks.
Filtration of air masses
The ventilation system of such industries must be equipped with air filtration, which includes:
- A glass fiber filter installed in the space above the ceiling to clean the air flows entering the box.
- Coarse pre-filter elements to extend the life of expensive fine filter elements.
- Fine filters, which are mounted directly in the ceiling of the room
- A cardboard filter that takes on all the contaminants when the air flow leaves the box.
- Charcoal filter for absorbing unpleasant odors from the air and its final cleaning before being released into the atmosphere.
Calculation of air exchange and equipment performance
The calculation of the performance of ventilation equipment for painting boxes is carried out based on the volume of the room and the frequency of air exchange. The whole complexity of the calculation lies in the fact that the rate of air exchange for ventilation of spray booths, SNiP does not regulate in any way. The multiplicity values are calculated based on the MPC of solvents and aerosols in the air masses of the box when painting and drying the painted product.
MPC for the solvents most used in coloring:
- Gasoline — 5 mg / m3.
- Xylene — 0.2 mg/m3.
- Toluene — 0.6 mg / m3.
- Benzene — 1.5 mg/m3.
The highest maximum allowable concentration of the solvent in the air is for the pentane solvent, the MPC value for which is 100 mg / m3.
The speed of movement of air masses in such production is calculated depending on the technological process and the MPC of aerosol compounds in the air. According to the “Designer’s Handbook” part — 3 of 1992. under the editorship of N.N. Pavlov and Yu.N. Schiller, when working with the release of aerosols, the speed of movement of air masses should be at least 1.2 — 1.5 m / s.
The video shows the effective operation of the ventilation system:
Do-it-yourself ventilation for painting plants
After completing the finishing work and installing lighting equipment, it was the turn to equip the garage for painting, with a ventilation system.
- An air intake should be arranged under the ceiling. Air intake can be carried out using a heat gun with the required capacity.
- From the heat gun (under the ceiling), a network of flexible air ducts should be laid out with eight air supply points, made evenly around the entire perimeter of the painting box.
- Each inflow point should be directed towards the center of the chamber.
The floor of the painting room is the most important element of its ventilation system. It is made of perforated metal, through the holes of which the contaminated air masses are pumped out.
To organize the hood, you should:
- Raise the floor level by 20 cm.
- Make a central part from a perforated sheet of metal or weld a lattice from a corner and fittings.
- Install and seal an air duct under the floor to remove air masses from the room to the atmosphere.
After completing all these procedures, you will make sure that do-it-yourself ventilation in the spray booth is quite difficult, but quite possible.
If you decide to make a painting room with your own hands, then when calculating, be guided by a 200-fold air exchange created by a supply fan.