Harbor Freight Tools that don't suck

[patrick_g]

Water - Here's Why

Yeah, thanks, I got it but...

If there isn't water in the air than there isn't water for the compressor to remove.

I understand why compressors have condensate to drain. Compressors don't make water, just remove it from solution. Water is actually in solution in the air. If you dry the air upstream of the compressor then there is no water to condense in the compressor.

My question related to whether or not the dryer intended for use downstream would work OK upstream. One of my concerns is that the piston on its suction stroke would be starved for air by the flow resistance of the dryer. That is why I mentioned an "accumulator" tank for the input. The air coming out of the dryer would flow through that tank on the way to the compressor. Then when the compressor was trying to suck in a cylinder full of air it would be sucking on the capacity of the accumulator not the capacity of the itsy bitsy diameter output line of the dryer.

If most of the water was removed upstream of the compressor then the compressor's tank should stay dryer.

Not cost effective but... you could put a dehumidifier (small air conditioner with tank to hold condensate or plumbing to run it to a drain) in an enclosure and let the compressor suck its air from that enclosure. Another way to give the input of the compressor dry air.

Sorry I didn't make my question clearer. ...one of the shortcomings of not being in your audience's presence.

Pat

 

[ThomasH]

Pat -

Two problems come to mind with what you are suggesting. First, the HF unit works simply by cooling the air, and the water condenses out of the air. If the air is not heated, it will not be but a fraction as efficient at removing water. Secondly, the volume of air out of the compressor is a fraction of the volume on the intake side, so the unit would have to be upsized in order to support the intake needs.

Tom

 

[crazyal]

My refrigerated dryer has a simple bowl where the compressed air flows into it spraying against a disk then out of it. The water, which was a vapor when it went in is now a liquid and collects at the bottom. The cooling of the air only serves to reduce the temp of the water so it turns to a liquid.

If you try to do it before the compressor the cooling part would work but the water separator wouldn't (as it needs the air flow to spray onto the disk to get the water out of the air). Plus the last thing you want to do is restrict the air going into the compressor. Compressors don't suck, they create a low pressure zone that requires atmospheric pressure (about 14psi) to push the air into the pistons.

 

[patrick_g]

Pat -

Two problems come to mind with what you are suggesting. First, the HF unit works simply by cooling the air, and the water condenses out of the air. If the air is not heated, it will not be but a fraction as efficient at removing water. Secondly, the volume of air out of the compressor is a fraction of the volume on the intake side, so the unit would have to be upsized in order to support the intake needs.

Tom

Tom, The volume thing is what bothered me and brought up the tank to be added to the input but I see your point. Now as regards heating... heating lowers relative humidity and detracts from condensing out water.

There is a Viet Namese American with a system using special cool tubes that would help with drying. Placed in the air stream up stream of the chiller they pre-cool the air condensing more water than without them when the air passes over the evaporator coils and because you don't get something for nothing the air gets the heat back after passing through the cool tube and this warming lowers the relative humidity of the treated air. Sets of these cool tubes are available off the shelf. They use no power beyond a little air friction passing the air through a heat exchanger twice and dramatically increase de-humidification performance. They have no moving parts except vapor and liquid inside the metal tubes. They are typically configured in a "U" shape to facilitate passing the air stream through twice.

I don't recall the guys name but here is a link to a Gov site telling about it. These tubes are used for moving heat from one place to another also such as electronics waste heat internal to the F-111 Swing Wing to the outer skin where it is shed. Hot running cpu CHIPS IN FAST pc'S use them.

Energy Savers: Dehumidifying Heat Pipes

Patrick.

 

[sixdogs]

This is one of the best low-buck HVLP paint guns around. It is not a cheap gun. It's usually on "sale" for around $30 and the 20% off coupon makes it better. I have put down a lot of alkyd enamel as well as acrylic enamel on farm equipment and it works like a champ. Buy the throw-away paint cups--often on sale for $6 for 5 of them-- and clean-up is no longer a chore but a couple minutes.

HVLP Spray Gun w/ Gravity Feed

5 Piece Air Spray Gun Disposable Paint Cups

Painting is so easy now I have been using more cups than I figured.

I like this spray gun stand--clamp it tight.
Universal Spray Gun Stand


This one is awkward and not worth it.
Gravity Feed Spray Gun Stand

 

[ThomasH]

<snip> Tom, The volume thing is what bothered me and brought up the tank to be added to the input but I see your point. Now as regards heating... heating lowers relative humidity and detracts from condensing out water.

Patrick - not to argue the point, but the differential temperature of going through the cooler is what condenses the moisture (at least up to a point). If the air is cooler, the AC portion of the cooler won't be as effective as when it was warmer. In other words, AC units are more effective when the difference in temperature that they are trying to cool is a good bit higher than the ambient room temperature. It is easier for an AC unit to achieve a 40 or so degree temperature drop (and cause condensation) with a higher air temperature.

Tom

 

[kootch88]

I try to never by Chinese whenever possible, although that is very difficult. I used to buy whatever was cheapest as long as the quality was there but I realized I was just as responsible for shipping jobs out of our country as the corporations looking out for the best interest of the company rather than our country. Harbor Freight is of course Chinese Central.

I know, I bought a tractor made elsewhere, but that was purely for quality, my physical requirements as a cripple and price too, I can not lie.

My friends think I am crazy for doing this, and even more so for trying to buy from the local guy, but that is also why I did not go to N.H. to buy my tractor, because I feel an obligation to do what I can to support workers here in the U.S. and local businesses.

A quick disclaimer, my wife is ethnic Chinese, and somehow she seems disconnected from the conditions in that country, unconcerned almost. Perhaps because she comes from money there.

 

[Brad_Blazer]

Yeah, thanks, I got it but...

If there isn't water in the air than there isn't water for the compressor to remove.

Pat

You didn't quite get the linked article. Two things reduce the ability of water to remain a vapor in air: high pressure and low temperature.

When you reduce pressure through a high efficiency nozzle the temperature effect outweighs the pressure effect and even more water will come out which is why water is such a problem when compressed air is used. Of course water also condenses whenever the temperature of saturated compressed air drops and this will occur throughout a system without a dryer.

The compressed air dryer uses both high pressure and low temperature in combination to reduce the fraction of water in the air. A dehumidifier operating at atmospheric pressure would have to run much colder to achieve the same effect which would use more energy and create problems with freeze-up i.e. the moisture would always freeze on the coils which would require a complicated thaw cycle.

The best place for the air dryer is after the compressor tank. The tank will act as a pre-cooler, removing moisture due to compression and cooling of the hot compressed air as it approaches room temperature. Since there is water and air in your tank the relative humidity will always be near 100% based on the temperature and pressure in the tank. The post-tank dryer will then remove more moisture so you can use the air without getting further condensation.

 

[mbrun]

rsewill,
Typical warranty below from HF on hand tools.
"Manufacturer Warranty Detail Lifetime Warranty. We guarantee this Tool to be free from defects in material and workmanship for the life of the product. Limitations apply."
If it is defective in normal use they will replace the tool just like Sears. I've never had a problem returning an item. Sometimes I just get my money back. Same thing I do at Lowes and Sears.

I have always found that wording amusing, "for the life of the product.". Isn't the life of the product the period during which the product in-fact performs or is capable of performing its intended function? Once the tool fails this criteria is that not the point at which it is dead? So once the product is dead, does that not mean the tool is no longer covered by the warranty? Hmmmmmmmm?

 

[sixdogs]

I have always found that wording amusing, "for the life of the product.". Isn't the life of the product the period during which the product in-fact performs or is capable of performing its intended function? Once the tool fails this criteria is that not the point at which it is dead? So once the product is dead, does that not mean the tool is no longer covered by the warranty? Hmmmmmmmm?

I think that's just a hedge against legal claims or things that might happen decades from now on issues unseen at the moment and out of bounds of the product and it's intended use. Almost everything today is a "Limited Lifetime Warranty" and I figure it's a "just in case" clause and a sign of the times. HF has 100% stood by issues for me.