Shop Air Filters. huh?

[David Hostetler]

Okay guys, how about a test? Does anyone have a manometer built? I can piece one together after the holiday, and a test would prove, or disprove the assertion. I still think a discernable pressure differential is complete hogwash, but actual testing will show without a doubt if it is or not. Even if it is, say for example your shop is in an attached garage, what does it matter? If there is enough pressure differential to blow by the weather seals either your seals are in terrible shape, or your ears will implode...

[Scott T Smith]

Actually due to Venturi effect could he actually be pulling outside air into the shop?

Good point, but the angle on the end of the tube would have to be reversed in order for it to draw a vacuum.

[dan grant]

I just run my air compressor and air filter at the same time to offset each other.

your quick tonight

[Van Huskey]

I think the way to accomplish the task with certainly would be to use a fan that flows to the outside with just enough flow to keep constant flow through the air infiltration sites from the rest of the house, it wouldn't have to be a lot but more than this "tip" will produce.

[Phil Maddox]

When I over pressurized the shop this way, I just have my wife fill up the tub with water in the house to even out the pressure.

[Matt Meiser]

I guess I should submit my brother's tip about letting all the air out of your compressor to reduce its weight when moving it.

True story that happened 8 years ago today when we moved here. He bumped the valve on my compressor and a small amount of air from pressure building due to temperature change came out. He blurted out "no wonder this ______thing is so heavy--it's full of air!" we had to take a break at that point

[Alan Schaffter]

Oh, well I might as well weigh in. It's a totally ridiculous concept, but evidently had just enough plausibility to get published?

First off, the initial statement,, "One of the drawbacks I found to shop filters is that they increase the air pressure inside the shop." is totally incorrect. Not sure how the author could come up with such a statement!?!?!?!?

But, if for some reason a connected shop was pressurized by any source, that small tube would not pump any air out unless the exit filter was totally blocked and even then it might not work. Reasons:

• A squirrel cage fans create little to no SP.

• The SP resistance of anything but a totally clogged filter is much less than the SP resistance of that tiny tube, especially if the unit is mounted in typical shop locations where the tube would need to be longer than a few inches. Think how much pressure it takes to blow air through just a short straw!!

,

• Depending on how the shop is constructed and sealed and how well the wall and the door between the shop and house are sealed, IF any air did get blown out via this system it is likely makeup air will infiltrate the shop from outside and not necessarily from the house.

[Ron Jones near Indy]

I have found that my shop dog's wagging tail will cause enough air movement to offset any air pressure gain from my JDS unit. I always knew he was a valuable asset to my shop.

[Anthony Whitesell]

I guess I should submit my brother's tip about letting all the air out of your compressor to reduce its weight when moving it.

True story that happened 8 years ago today when we moved here. He bumped the valve on my compressor and a small amount of air from pressure building due to temperature change came out. He blurted out "no wonder this ______thing is so heavy--it's full of air!" we had to take a break at that point

As for you brother's situation, I don't think you could tell the difference between full or empty. I race go karts and we used portable air tanks. About 5 gallon tank but without the compressor and motor. Just the tank, a small gauge and a hose for filling the tires. It is heavier after being filled than when you carried it to the compressor, after you spent some time lugging it around. Ten atomspheres of pressure added to an aluminum tank does change it's weight perceptively.

[Chris Parks]

I suggest leaving all lights off as when they get hot the heat causes the air to expand and then the air can't escape and if they are left on long enough we will have an over pressure situation and the whole lot will explode. Now the manufacturers of all light globes are going to have to put warning labels on them saying to leave a door open to prevent the risk of explosion. I might have it all wrong of course........

[Thomas Bank]

I guess I should submit my brother's tip about letting all the air out of your compressor to reduce its weight when moving it.

I've convinced more than a few people that a full tank of helium is lighter than an empty one...

[Phil Thien]

As for you brother's situation, I don't think you could tell the difference between full or empty. I race go karts and we used portable air tanks. About 5 gallon tank but without the compressor and motor. Just the tank, a small gauge and a hose for filling the tires. It is heavier after being filled than when you carried it to the compressor, after you spent some time lugging it around. Ten atomspheres of pressure added to an aluminum tank does change it's weight perceptively.

Not surprised the weight would change, but I'm surprised you'd be able to feel the difference. I was told scuba tanks weigh about a pound more when full than when empty. But those things hold something like 3000 to upwards of 4500-PSI. They are also much smaller than 5 gallons, though.

I wonder how much more your tank weighs when full.

[Bob Deroeck]

Hi,

Ideal gas law shows a 5 gallon tank at atmospheric pressure and 60 F contains 0.05 pounds of air. At 100 psig the same tank contains 0.40 pounds of air. As I age my body is complaining more when lugging my compressor. It must be due to the extra air in the tank.

Bob

[Phil Thien]

I guess it doesn't surprise me that he can feel that 1/2 # then, as the aluminum tank starts-off pretty light (I'd guess). I know a lot of scuba guys can feel the difference between a full and empty tank, and those things are kinda heavy and they're only seeing a 1 # difference.

Kinda interesting.

[Anthony Whitesell]

And we carry the tanks several hundred yards throughout the day/weekend. To the compressor, to the work area, to the starting line, back to the work area, back to the compressor, back to the work area. If you put an empty and a full one next to each other, you can actually tell. I'm only talking full vs empty. Not anything in between.