Air Distribution

That's because you don't know the difference between HEAT and TEMPERATURE. Things can be colder in temperature yet contain more heat. At least if you have progressed in scientific understanding to the 19th century. A bucket of ice contains more heat than a bucket of steam.

Sure. It is indeed convenient. Just not economical.

You can run your air tools off a 3500 psi scuba tank, but it is a huge waste of energy.

I don't see that as a correct analogy in the case of air flow through a regulator. In that case the mass flow of air will be the same so any heat liberated should be seen to heat the regulator or outgoing air stream. My understanding of a regulator operation is that it is closer to a switching voltage regulator rather than a linear regulator so much more efficient.

But a pound of steam contains a lot more heat than a pound of ice. ALLWAYS.

In a nutshell: The operating machine (piston, motor, whatever) uses air-------pressure drops below your set level-------a poppet style valve opens and allows air pressure to enter the machine----the pressure rises in the machine to your set point-----air stops flowing into the machine----now repeat this rapidly and you have a modern pressure regulator.

No air blowing off No "hot" regulator Understand? Unless??? Are you a quibbler?

dennis in nca

I believe you just don't understand how regulators work.

But there is that question about "quibbling" to be answered.

dennis in nca

"> > Throttling is the process of lowering the pressure by friction."

A regulator is not a throttle, it's a gate.

dennis in nca

"My understanding of a regulator operation is that it is closer to a switching voltage regulator rather than a linear regulator so much more efficient."

Exactly. And the name sometimes used to name this analogy is a "gate" similar to a common switch.

And I'm 100% certain that many hundreds (if not thousands) of engineers have worked untold hours making this regulator (gate) operate as quickly and efficently as possible.

So back to where we were. Pumping your system to a higher pressure will have a more economical effect in larger buildings with more air line because, in effect, you are turning your distribution network into a more efficent extension of your compressor's tank.

Don't worry about wasting your energy dollars, they're not wasted.

dennis in nca

No. Any expansion of compressed gas loses energy, just as any compression requires it. It matters not how the trip is made from one state to another, all that matters are the end points, and they are the same whatever regulator principle you are using.

Let me state it as simply as I can in terms of conservation of energy.

It takes a certain amount of energy W1 to compress a given volume V of free air to some pressure P1. It takes *more* energy W2 to compress the same V to a higher pressure P2, so W2 > W1. Now if you output this same V at a down-regulated pressure P to your tool, where P

"Richard J Kinch" wrote: (clip) Here's a thought problem to consider: suppose you have a compressed

Analogously, if you discharge a perfect capacitor with a perfect

^^^^^^^^^^^^^^^^^^^^^ As to releasing compressed gas and doing no work, I can think of only one example: popping a balloon in outer space. The air molecules would leave the area at some high velocity and keep going forever. A perfect capacitor shorted with a perfect conductor cannot exist. It would result in infinite current, and I guess the energy would leave in the form of electromagnetic radiation.

But I agree with the point you are driving at: letting compressed air drop to a lower pressure without doing work must produce heat, some of which is unavailable, thermodynamically, to do work. In actual practice, none of the heat is used--all is wasted, because people do not put heat engines in their compressed air lines.

If you want to get picky, releasing the pressure through an orifice like that regulator develops COOLING, just not very much.

And with an electric motor on a compressor reducing the duty cycle between run times is very important. Short cycle the compressor motor for fifteen seconds on and three minutes off because you have no excess receiver capacity, and you'll soon have a burned out motor from deep winding burns.

If you have enough storage tank capacity (excess pressure above shop lines) so the cycle is five minutes on and 120 minutes off, the same motor will live a long useful life.

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Depends on the regulator. VERY MANY work as described, but there is more than one way to skin a cay - or regulate air pressure.

Not so. the air will be cooler at the output of the regulator than at the input. But it will be significantly _less_ cool than if expanded through an air motor or turbine.

The wasted energy has already happened, it's coming out of the air cooler or compressor cooling system. If the air pipe to your windy drill is almost too hot to hold, due to no cooling in the system, then your efficiency will be noticeably higher than if the inlet air is at ambient temperature. If you use a higher tank pressure, you waste more heat out of the air cooler. You don't get that heat back. Ever...

A reasonable assumption is that for 90psi air, it takes 4hp of compressor to produce 1 hp of air-tool power. That's not good.

Mark Rand RTFM

We've been here before...And the last time we went through this, Mr. Kinch was one of the few here that knew what he was talking about. Restating the above: Forget about what is happening in the regulator, just consider this: Does it take energy to raise the pressure of a fixed volume of air? Work is done by a piston or other method. Obviously, yes, so how can you let air expand (without doing useful work) and not lose energy?

And how much MORE Hp at 100, 110, 120 and 130 PSI? That's the question. Is it linear, delining, in increasing slope?

Yes, so? That's a given going in - you lose the potrential energy when you get rid of that heat. But the heat is bad on the equipment anyway, it's counter productive trying to hold it in.

You lose a little energy dropping the 150 PSI air in the tank down to 90 in a regulator for the tool input - but that air tool is still a hell of a lot smaller, and lighter, and cooler running than an equivalent HP electric tool.

Much easier to counterbalance for all day use on an assembly line, and can run all day without overheating and failing. (Just have a mist oiler on the air input so it doesn't seize up.)

And you eliminate the shock hazards of running electric tools around water, and seriously reduce the fire hazards (electric sparks) of running electric tools in hazardous work areas around flammables.

Air tools are a trade-off in efficiency - but when you need to make the trade to get a smaller and lighter tool that does the same work, you do it willingly.

If you need to keep energy efficiency higher than with pneumatic, you can do the same thing with hydraulic tools. Put a PTO hydraulic pump on the truck, and they make twin hose reels and hydraulic pavement breakers, concrete saws,chain saws, rammer and soil compactors, etc. So Cal Gas Co. rigs a lot of their service trucks this way.

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You're no doubt correct and I was addressing the comon regulator we all use in our shops.

dennis in nca

Yes, the energy wasted in after-coolers and refrigerated air dryers is high but "waste" can be defined in more than one way. I use the common usage in a machine intensive environment where keeping your machines running at peak efficiency is the goal; the costs are absorbed by your budgeting/pricing process.

This is the reason why having a high pressure system or a screw type compressor is important in industry.

Nothing wrong with saving money wherever possible.:)

dennis in nca