Abrasive Blasting 101
Updated February 2022: An abrasive separator reclaimer is a pneumatic centrifuge capable of separating usable abrasive from dust and unwanted worn abrasive while creating the negative cabinet air pressure required for all blasting cabinets. This not only helps reduce the cost of abrasives, it vastly improves visibility inside the cabinet as smaller dust and spent abrasive – carbon, paint and rust – are removed while the unit is being used.
Having a blast machine without having an abrasive separator reclaimer is comparable to operating an automotive engine without an oil filter. You will need to change the oil more often, even though some of the oil is still good. The more you travel, the more good oil you throw away. Blasting is the same: the more you blast without a separator reclaimer, the more good abrasive you will throw away.
Abrasive separator reclaimers are available in different efficiency ranges that should correlate to the abrasive size used. Some separators operate with media sizes between 0-150 mesh and others are intended for finer materials of 180-400 mesh. In addition, separator reclaimers are available in different cfm ratings, with larger separators for larger exhaust blowers. Keep in mind that cabinet visibility is directly related to cabinet air changes per minute.
Vacuum blowers are the lowest cfm used for abrasive blasting cabinets. They are used to meet the minimum requirements for negative cabinet pressure to prevent abrasive escape during the process, but unless you have lots of air changes per minute, visibility will be poor when cleaning dirty parts. The separator reclaimer is used so a larger blower can be installed creating better cabinet visibility and more cabinet air changes per minute without any abrasive loss. (For reference, most Media Blast units operate at one air change every 1-2 seconds based on the cabinet size.) This is not possible with any vacuum blower – even with the smallest of cabinets.
How does a blast cabinet reclaimer work?
Imagine a truckload of birds and someone beating on the side of the truck container with a baseball bat. This keeps the birds flying and constantly feathers. The object is to remove the bird feathers so you can see the birds inside the truck.
Yes, you can remove the feathers by cutting a hole in the truck container and attaching a blower assembly to the hole. Turning on the blower will suck the bird feathers out, but it also removes any bird that gets close to the blower exhaust holes! After a short time you have no feathers (hopefully) but you also have no birds. If you try to correct the problem by using a small blower, the feathers at the end of the truck in the dead air spots will simply fall down only to be uplifted by the wing beating to obscure your view. The solution is to put a net over the exhaust hole (which acts as a separator reclaimer) where the blower is attached. The net allows only the feathers to be removed but not the birds.
While this is a simplification, the separator acts as the net using an air centrifuge design. Nobody wants to use a blast machine full of used abrasive contaminated with rust, paint and carbon so being able to remove those particles with a separator is very helpful.
If the descriptive information on a machine includes phrases like “Includes Abrasive Recycle” it’s helpful to know that technically gravity acting on spent abrasive and pulling it down can be classified as “recycling”. Another thing to be wary of is “Abrasive Baffle Plate” which is the term used to describe a simple piece of steel over the cabinet exhaust hole.
Remember to ask your sales rep why a machine doesn’t come with a separator reclaimer included, and if they tell you that you don’t need it, ask them what size the exhaust blower is in cfm, cubic feet of air removed from the cabinet for visibility. If it’s 100 cfm they are most likely using a vacuum blower motor assembly to reduce the cost of the blower. As we touched on earlier, vacuum blowers are used to meet the minimum requirements for negative cabinet pressure to prevent abrasive escape during the process and typically