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6. Paint Mixroom
Mixroom is a special area equipped according to all requirements and safety instructions made for work with the 3d danger class materials. This room is fully ventilated; moreover each tank is connected to separate outlet ventilation for taking out volatile solvents and reducing risk of explosion.
The process of ready-mix preparing is very simple and consists of the following stages:
- A barrel with initial PWM viscosity (secondary primer, basecoat or ) is thoroughly mixed up on device looked like rollers, the barrel is rotated during 15 minutes clockwise or counterclockwise.
- Mixed-up barrel is passed to tank.
- Paint is downloaded by mini-pump into tank.
- According to dilution percentage of acceptance test a solvent is added to tank with paint.
- Mixing of paint and solvent is lasted about 1 hour, after that material viscosity is measured by viscosity gage. If viscosity is normal, it’s ok, in other case it is necessary to add stiff paint or solvent and make some measurement in an 1 hour.
- Measuring control is repeated every 2 or 3 hours, depending on the length of paint pipe.
It is important to remember that if the material viscosity decrease or arise above specification it will affect the paint line and lead to mass defects.
This department is a top-priority one for paint line.
Material filtration is accomplished in special “bowls”. Filter change is made after termination or pressure fall (boosting).
- For secondary primer and clearcoat there should be set a filter of 100 micron cell.
- For metallic and non-metallic there should be used a filter of 200-250 micron cell. If the filter cell is lower, filter will “catch” metallic and the paint of bodies will be of different colors and shades.
Measuring of material density:
- Secondary primer and clearcoat are measured by viscosity gage B3-246, nozzle #4 (little known fact, progenitor is cup Ford-4).
- Base enamel AEO and AEM is measured by viscosity gage ISO-4.
Viscosity gage is a special cup with nozzle which defines material density.
IMPORTANT in MIXROOM designing:
- The closer mixroom is set to paint booth the lesser money you will spend in future for the whole system servicing, i.e. pipeline flushing, draining, refilling, material renewal.
- Usually such rooms are located in separate small building very close to painting shop.
- Angle of pipe rotation should be maximum 60 degrees.
The above mentioned conditions will cut down expenses for pipe installation, pumps power, wastage while systems filling with paint.
In the design it is necessary to consider speed of paint flow in pipe, otherwise there will be a lack of materials in painting booth.