How to rid moisture in sandblast media

[tmt_92021]

Does anyone know of a way to keep moisture build up in the media of a sandblasting cabinet. The moisture keeps the media from flowing downward to the suction tube. Thanks.

[monte55]

out of compressor with at least 25 ft hose allowing the hot air to cool and the moisture to condense to liquid, then through a water separater then to your hose with tool. If you have lots of money, get a refrigerated air drier
system. hope this helps

[HayTay]

Originally Posted by tmt_92021 Does anyone know of a way to keep moisture build up in the media of a sandblasting cabinet. The moisture keeps the media from flowing downward to the suction tube. Thanks.

Unless you are storing your media in a moisture rich environment the media is not the problem. Except the moisture that is always present to a greater or lesser degree due to weather conditions and the associated humidity, almost all of the moisture that is present in the media comes from the compressed air used to project the media out of the nozzle.

If your doing sandblasting on a hobby or occasional level what you need is a good moisture separator as close to the sand blast nozzle as possible. A moisture separator will filter the excess water from the incoming air supply. Another name for moisture separator is condensate separator, you can check them out on McMaster-Carr's website by looking at "Compressed Air Condensate Separators". If your doing high volume sandblasting using multiple sandblasting cabinets or your shop has other high volume compressed air requirements you should look into an air dryer in addition to using moisture separators.

Additionally, I've seen a lot of people who have moisture separators that still have problems with moisture in their media. The moisture that collects in the moisture separator must be drained periodically. This depends on a lot of factors including humidity, the dew point, and the amount of sandblasting being done. Moisture separators should be drained prior to the start of sandblasting and periodically during the blasting session. After a while you get the feel of when to drain the moisture separator.

Moisture also collects in the tank(s) of the air compressor and they should also be drained daily. Look for the petcock located at the bottom of the tank.

As for moisture already present in your media, the media reservoir and ,both media and air supply hoses should be emptied and thoroughly cleaned out. Fresh media should be used to replace the moisture rich media.

Depending on the media, I've used several methods to remove the moisture from wet abrasive. If the media is sand (BIG NO-NO with OSHA), aluminum oxide, crushed glass, glass beads, silicon carbide, steel shot, or steel grit the media can be spread out on trays and either baked, blow dried or left to dry in the sun. On the other hand, if the abrasive is pumice (very fine powder), corn cob, plastic, or walnut shells I would use only the tray and sun dry method.


Happy blasting,

HayTay

[NC Cams]

Uncooked rice in a salt shaker is a natural dessicant. Might work in a blast cabinet.

The important thing is to NOT let the moisture get into the cabinet via the air stream.

Pipe layout can have a lot to do with how much and if water gets to the blast media. I saw a neat outline on pipe layout in a dessicant drier container for compressed air. They essentially had the pip (metal to act as radiator) flowing UP hill from the compressor. Water would condense and flow back towards the compressor but not into due to the was the tubing flowed.

All T's were upside down. Air entered the pip from the TOP with the leg of T pointing up. This way, any water than condensed could be drained back down the sloping tubing to a drain tap.

Lines taking air from the pipe also were via upsidedown T's. Condensed water didn't flow up hill. There were other tricks but it all added up. Basically, you have to THINK before you plumb and remember that water flows down hill, air is lighter than water and cold is on the right.

[HayTay]

Compressing air generates heat. Hot air can hold more moisture than cold air. Think of the weather, in the summer it is usually "hot and humid" and in the winter it is usually "cool and dry". This is not always because there is less moisture available but because of the air's ability to hold moisture. The weather cycle is a prime example: Hot air laden with moisture rises into the atmosphere where it cools and the moisture condenses to form clouds. When the condenstation reaches levels where it can be no longer sustained in the atmosphere it falls to earth in some form of precipitation.

That may be too abstract, let's relate that to beer. The beer you drink will tend to "sweat" more in the summer than in the winter. How's that? Any thread that mentions beer is bound to generate more responses.

Taking into consideration the above arguments, most compressors, due to the "noise factor" are not located in the ideal environment. These compressors are usually outside under an awning, or in a shed, or on an outside wall in a room without environmental controls. Simply putting the compressor in an interior room that is temperature controlled can reduce the amount of moisture present in the compressed air.


Meterology101, PSU W-B Campus, 1987,

HayTay