Blasting units containment units for blasting operations where the operator works inside, protected by helmets and special clothing.
They are designed to prevent traditional open-pit sand operations by eliminating the high degree of pollution and allowing the use of nobler abrasives as they accept adaptations of ventilation, recycling, purification and dust filtration systems.
They also have the advantages of being weather-independent and can be mounted close to or even on the production lines themselves.
2-1) Cabins themselves
They are developed according to the probable maximum size of the pieces, having units with 7 or 8 m3 or more than 5,000 m3, for the ship industry, generally.
They can be built in masonry or structured metal or in modules, the important thing is that walls and ceilings are continuous, without openings.
Generally, with the help of hoods, a horizontal air circulation is carried out which drags the suspended dust in the longitudinal direction of the cab (smaller section). Air is suctioned through air vents mounted at one end, through openings protected by screens and shields at the other. As with cabinets, the presence of internal negative pressure is also important.
The main (service) and auxiliary (jatista) doors must be hermetically sealed with rubber seals. Often the ventilation openings are in the main doors themselves and the pickups in the opposite bottom.
2-4) Abrasive Collection
There are several systems for collecting abrasive that falls on the cabin floor to bring it back into the process:
It is the simplest process and one that requires the least investment. The floor is coated with flat sheets and the material, during a break in blasting, is dragged by hand or with vehicles suitable for hoppers or laterally installed conveyor threads.
2-4-2) Helical threads
In this case the floor is fully lined with grids that do not retain the abrasive that is continuously collected by lower rails with helical threads, concentrating the material at one or more points.
2-4-3) Dragging System
Under the mesh floor, flat and flat rails are mounted and the collected material is dragged by reciprocating longitudinally moving vanes.
2-4-4) Suction system
In this case, under the mesh floor, parallel “M” rails are mounted and the abrasive is collected and transported by suction. Both this system and the former have the advantage that they can be mounted directly on industrial floors, requiring little or no civil work.
2-5) Purification of Abrasives
As in the case of cabinets, the collected materials are taken to a purification system. When steel shot is used, which is the most common abrasive in booths, it is conveyed to the scrubber by means of a tank lift. The dusted and sifted material falls into silos, from where it returns to the process. In the case of suction pickup, generally employed for lightweight materials, cyclones are used to collect the material and separate dust impurities. In cases where purification requirements are higher, other features such as vibrating screens and magnetic filters may be interspersed.
2-6) Dust collectors
These are indispensable systems for trapping dust entrained by ventilation before returning air to the atmosphere. The air intake, in addition to inside the cabin, must suck from the lift and the purifier creating, as has been said, negative pressure throughout the system.
cabs The current technological development allows a wide versatility in the cab design, adapting them to the most diverse operating conditions.
2-7-1) Marine and Offshore Cabins
Theoretically, there are no limitations on the maximum dimensions with which a cabin can be constructed.
Problems such as moving large and heavy weight irregular parts are solved with the ingenious multi-rail system with cars freely positioned under their support points.
Each particular case requires special devices to rationalize operating conditions.
2-7-2) Blasting and painting booths
The development of multicyclone dust collectors to replace bag filters or cartridges that do not resist paint particles and solvent gases has opened the possibility of using booths for blasting and for subsequent painting reducing the time between the two operations and eliminating the movement of parts.
2-7-3) Climatized cabs
To safely avoid contamination of already blasted parts and to guarantee the maximum temperature requirements required by modern protective inks, the cabs can be adapted to complete cabs which maintain the internal temperature. below 26 ° C and between 45 and 50% relative humidity during all blasting and painting processes. In this case, the internal pressure becomes positive and the expelled air is purified for dust and solvent gases by special filters before being released into the atmosphere.
2-7-4) Shot Peening Cabs
Devices for moving parts such as rotary tables or shafts or driven cars, for moving pistols or pressure nozzles, with programmable timers, in short, with all devices required for repetitive operations and Impersonal features, such as those required for shot peening, can also be adapted to booths of any size.