Compressed Air Dryer for Home Shop

I have something similar to a drip leg. I put inline an extra regulator that I don't really need. The bottom of the regulator assembly has a drip bowl. It seems like a good idea but it doesn't catch much water.

Thank you,
Bruce

Your drip leg should be at the bottom of a long vertical pipe, as long as you can make it and as near the reservoir as it can be. The drip leg should be DRAINABLE, and do it. As far as it is practical, locate this vertical in the coolest part of your shop... let that moisture condense, it'll hit the drip leg so you can get rid of it.

Inline filters help a little bit, several versions can be had for <$50 USD each.

Thank you,
Bruce

Heat the air before using it.

What type of volume you talking about when you do use it?

Desiccant air dryers are less expensive. Price usually is dependant on flow volume.

Sand Blasting does require a large flow,.... +15 CFM's at least.

I don't have a flow volume in my head. Pressure is about 90 PSI and sand blaster guns I have would be a low quality and a medium quality gun for the home market. Spec sheets lost years ago.

A large pressure cooker such as those used for canning. could act as a receiver. the hard part would be routing the evaporator coil from a dehumidifier inside the pressure vessel and sealing it while it is still connected to the dehumidifier unit.

The other concerns would be the pressure limit for the vessel and the evaporator tubing.

Basically a DIY cold plate dryer. The time, materials and safety of that project just don't have a light bulb lighting up in my head yet.

I admit it is complicated from a construction standpoint, but as far as cost, used dehumidifiers and those big pressure cookers are pretty common in flea markets and garage sales. I made a vacuum dryer for smaller motor stators with a pressure cooker, a hot plate and a vacuum pump.

Those dorm room refrigerators make cheep coolers for minnow tanks.

Anyway, it was just a suggestion.

You keep your minnows in a refrigerator?

Only the ones that are not afraid of the dark.

Another one: the peltier unit out of a big Colman cooler?

That one I like. I don't know about the BTUs and ability to stay cold with this much air flowing over it but I do like the idea. Still, I'd like to blast this weekend and next weekend. Squeezing a DIY dryer in front of the other tasks is a problem.

I like the one SolarEagle gave, the logic of the distance from the tank and the surface area makes sense.

Forget the pressure cooker - they are only used up to about 15 PSIG. Anything you can do to cool the air before the receiver and then heat it, as Crabtree said, before the sandblaster will help.

Why not dry the sand? Heat-drying and then let cool for an our or two before blasting should not be that difficult. S.M.

I gave up on sand from the yard years ago. Too much effort to screen it and there was the risk of it being damp. This is "dry" blasting abrasive from Tractor Supply. I'm sure that it has some moisture content but it feels dry and flows well from the bag. My assumption is that all significant amounts of moisture are coming from the humid air.

In Florida we have two types of water. We have thick water that is found below sea level. We also have thin water that is found above sea level. My problem is either (or maybe both) that my air compressor is converting thin water to thick water and letting it flow down the line or as my compressed air expands it cools enough ambient air to condense the water out.

I wonder if the ambient air coming in through the sand line is condensing after mixing with the expanding air?

Bruce, are you using a pressure pot type sand blaster that hold ~100 lbs of sand?

If so, I've fought water that causes the sand to cake where it's picked up off the bottom of the pressure pot. I installed 3 additional valves (1/4" NPT ball valves), This way I can isolate the sand feed, and force blowing it out the delivery hose. If your pressure pot is the same as mine, it has a input regulator with a input ball valve. The output of the regulator splits into 3 hoses, one to the top of the pressure pot, and 2 to the bottom of the pressure pot where they recombine at a tee.

I can isolate any of these 3 pressure sources. I do wait for the 5HP compressor tank to cool down when this problem occurs and blow off the tank water. Then I can clear the wet sand from the where it comes out of the tank.

Thanks for the reply.

I do not have a pressurized sand pot. One is suction feed and the other is gravity feed. In both cases the sand is at ambient pressure.

I would try this first, it is cheap and should work well....

https://www.youtube.com/watch?v=ACPoyUM9yco

ps; if you have a split a/c unit nearby you could run the evaporator line along the length of the first pipe to cool it, if necessary.....

That looks simple and effective. I like it.

Thank you,
Bruce

Great link!

Very good common sense method of extracting moisture.

The spiral flat iron he spoke of could probably be replaced by a screen door spring,

stretched out to provide spacing between the coils,giving more surface area.

I know the following suggestion will result in quite a restriction for the flow volume,

but consider this idea:

Remove the condenser coil from the back of an old refrigerator and mount this to the

wall,and run your air through this,with a drain at the lowest point.

Also,drain your traps before you start the compressor,while the tank is the coldest.

If you have a choice when choosing to buy a compressor, choose the vertical over

the horizontal tank type.

This places your outlet further from the bottom so water is less likely to get into your line.

Good suggestions. Thank you.

That makes sense.

I'm not sure running two compressors in parallel is in my near future. I am, however, expecting my compressor to retire itself within the next year or two. Buying a replacement larger than necessary, along with other posted suggestions, all contribute to cooler air and less water.

Thank you,
Bruce

"For general utility sand blasting I use clean play sand from the big box stores"

I assume that you are referring to common beach or silica sand.

Not sure where you live, but silica sand has been banned as a medium for sand blasting procedures in most developed countries for more than 50 years and its use even in small operations carries a heavy fine in many of those countries, the use of a cabinet and filtering does not mitigate the liability.

Garnet, whilst more expensive, does a better job without the health risks.

Other alternatives include Corundum, crushed Walnut shells, glass beads, etc.

I use common play sand mostly, the same material that is used to sand blast bridges, trestles, large beams and the sort by many of the larger public and private corporations. It is compliance with NIOSH

http://www.cdc.gov/niosh/topics/blasting/

Full personal protection is provided by using a sealed blasting cabinet, negative pressure in the cabinet, a vacuum and a hepa filter prior to release of the air without the fine sand particles. It is only used within the cabinet. For exterior blasting most, if not all, blasting is done with sodium bi-carbonate, baking soda. With this product there is relatively no hazards other than personal contact with the high pressure discharge on the skin. For fine sanding the sand is removed from the blast cabinet, the cabinet fully cleaned and walnut shell flour, pecan shell flour or wood flour are generally used.

Don't know where you live but sand can be used here with appropriate precautions.

Good Luck, Old Salt

OK. That appears to be a US site. The UK and Australia (where I live) banned it in the late 1950s and Europe did so in the mid 1960s. The US would seem to be decades behind the rest of the world in providing adequate worker protection in this field.

Interestingly, this site (which is the same mob as the one you quoted) lists quite a large number of US case studies regarding silicosis among sandblast operators dating back to the 70s. Don't the health authorities over there pay attention?

Have a good look at the studies and you may be tempted to cease using that sand.

I was thinking of an old dorm fridge to contain the coil.

Does it need to be empty or can the beer still be in it?

Thank you for the detailed reply. Lots of good suggestions.

Big box store sand was what I used in between filtered yard sand and Tractor Supply blasting abrasive. I found the play sand was often very damp but construction sand was normally dry.

Bruce

Very interesting about the different sands sources. I tried construction sand but it was very wet from the washing of it during the suppliers processing. Tried drying it in the kitchen oven but that created too much shouting about me using her "work shop".

Tried the play sand and it was very dry with no wet clumps. Purchasing it in bags also it easier for me to handle it as compared to a shovel and bucket.

Good Luck, Old Salt

Run a pipe line from the nearest cool room or freezer to the intake of your compressor. Cold air does not hold as much moisture as dry air, then release it into a refrigerator or freezer again as often as you can afford compressing it again each time. When no more water settles out after each cooling use the compressed air for sand blasting ( or any thing else that needs dry air.). Second hand fridges can be collected for nothing from affluent friends. You seem technically capable to modify them for efficiency. Dry air for for very little cost. Happy sand blasting.

Thank you.

I never cease to be amazed at the time and trouble and cost people incur to avoid buying a dryer.

But even if you did fork out for one, you need to do a few things first to ensure the dryer would work properly, which means the air must be as cold as you can get it, and if you did these things you might find you do not need a dryer after all.

Much advice has been given already, but to sum up:

Make sure the compressor intake is in an area where it draws in cold air.

Make sure the compressors is kept cool.

Then make sure the compressed is cooled down and suitably drained at source, because it is at this point where the water vapour starts to condense. Without any cooling at source, the air will cool in the pipework and condensation takes place everywhere.

Make sure the compressed air is as cold as it can be at source. Initially by an aftercooler (a radiator and a fan) or a watercooler device - both followed by a filter/drain.

A readily available supply of cold water flowing through the cooler would be enough if the compressed air temperature leaving the cooler is below ambient - if immediately filtered an drained.

If the compressed air is not below ambient at the outlet of the cooler, then you will need additional cooling generated artificially by refrigeration techniques (a fridge dryer) or a coil in a fridge, again filtered and drained.

No more cooling will take place in the pipework, no condensation, and hence no water. Cooling by expansion at the blaster is not likely to be a problem because water vapour will not condense on the sand which is 'warm' by comparison.

Alternatively use desiccant techniques instead of a fridge techniques, but make sure the pre-cooling, filtering and draining has been done first. A pot of desiccant might last long enough for a work session, and the desiccant can be regenerated between work sessions.

Thank you.

I live in NC, and just use something like this. If things are really humid I'll crack the drain valve on the bottom of the tank in addition to the valve on the bottom of the filter.

Sandblasting, lacquer and automotive paint...no problems. At worst you might want to throw in a cheap in line dessicant dryer before your gun.

http://www.amazon.com/gp/product/B0000CBINA/ref=pd_lpo_sbs_dp_ss_2/178-9511459-5085022?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=lpo-top-stripe-1&pf_rd_r=1GD25S2C63D1ZQMKY1KK&pf_rd_t=201&pf_rd_p=1535523722&pf_rd_i=B003CLDT9I

Mine is clear, and I think it was about $15 from Lowes, Home Depot, or maybe an auto parts store.

The properly sized desiccant dryers perform better for an intermittently used home workshop. There is no additional energy consumption and the desiccant will last longer than you think. Mine will last over a year.

A refrigerated dryer is best for a high duty cycle production shop.

Maybe you could consider trying a different sand-blasting media that wouldn't turn to mud when exposed to water:

Media Guide

Note:
Above information is intended as a general reference guide. Consult Metal Preparations for specific media specifications.
1.) Sodium bicarbonate must be treated with a flow agent.
2.) Do not use silica sand in a hand cabinet.

Thank you.

I'm not sure but I may have been misleading with my term "mud". It is just wet sand clogging the gun and/or lines. I will try other blasting media but I suspect most will glob up when wet.

Bruce

It seems odd that while silica sand is specifically recommended against, three of the compared recommended media are fairly close physically and of similar chemical reactivity.

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I wonder why garnet dust, and dust from crushed glass or glass beads do not present the same hazards as dust from silica sand. Glass, whether crushed or beads is mostly silica. Garnets are crystalline silicate.

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It seems odd that the dust from these similar to silica media, once in the alveoli, would not be consumed by macrophages and trigger a similar inflammation response.

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Is it possible that the hazards are similar but that silica sand dust was the only media for which there was exposure on a large enough scale to enough people to notice the problem?

The main difference is that there is a whole lot less Silica dust in a comparable quantity of garnet. Most dust associated with Garnet blasting is Calcium Carbonate, Zircon and Ilmenite, which are all considered to be non-carcinogenic.

Silica sand consists of greater than 95% crystalline Silica whereas Garnet has around 0.2%.

The relatively smaller amount of silica dust thus produced by the use of Garnet, and the relatively larger grain size presents a lower risk than does pure Silica type sand.

Obviously, practical safeguards should still be observed as dust is still produced and can be inhaled using any media.

Often dangerous debris and heavy metals (ie. lead paint) are blasted off the surface of the job which have no direct correlation to the blasting media but which can be a health hazard in themselves

Thanks for the response.

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I understand there will, of course, be less silica dust if garnet is the media.

Calcium Carbonate and Ilmenite, are not garnets, but perhaps are part of some blasting media formulations sold as 'garnet'.

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I'll grant that the consumption of Zircon, Calcium Carbonate and Ilmenite is not carcinogenic. The thing is neither is consumption of Silica sand. Silica sand also has very low toxicity just like the other media listed. You could swallow a fair amount of silica sand or even dust every day, and with sufficient water to wash it down, and not have any long lasting adverse effects.

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Silica becomes problematic when it is inhaled as a fine dust. The thing is fracturing of glass media, garnets, zircon and even Ilmenite should typically be conchoidal/subconchoidal, like silica sand. Even if the other media do not create dust as quickly as silica sand, it seems like the problem would still be here, just slower.

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Your problem is that it is difficult and expensive to dry large quantities of air. If you are willing to dry air at a lower rate, you can use a desiccant, or a refrigeration type dryer with excellent results. You must just let your supply tank run down to the minimum acceptable pressure until it is recharged by by the dryer supply. If you require higher constant flow, you need to spring for a larger capacity dryer.

Thanks for the reply.

For my "quick and dirty" setup that I will need very soon I was thinking of basically what you described. It is not a good long term solution but if a "MacGyver" or "A-Team" solution is needed quickly for one weekend then it sounds good.