Scroll Compressors: Specs, Volume, Pressure & More

In summary: I am not sure. I am looking for a scroll compressor to use on a project I am working on, and don't really need anything specific. Volume and pressure are something I am curious about, but I don't have any other requirements.If anyone can help, THANKS :smile:In summary, Ron is searching for information on scroll compressors, and is looking for a specific type that he does not need. He is also looking for dealers or outlets that carry them, as they are usually surplus and have the best prices.
  • #1
RonL
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After quite a bit of searching I have had little sucess finding specs or sources of buying just the scroll compressor head. Wiki and a few other sites have good animation that helped in the understanding of just how they work, and what makes them good for some applications.
Most information has been very shallow, I would like to find information on, speed, volume, pressure, and specific size and mounting options, as well as possible dealers or outlets. Surplus is usually best for price, but there seems to be little supply on the market.

If anyone can help, THANKS :smile:

Ron
 
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  • #2
RonL said:
After quite a bit of searching I have had little sucess finding specs or sources of buying just the scroll compressor head. Wiki and a few other sites have good animation that helped in the understanding of just how they work, and what makes them good for some applications.
Most information has been very shallow, I would like to find information on, speed, volume, pressure, and specific size and mounting options, as well as possible dealers or outlets. Surplus is usually best for price, but there seems to be little supply on the market.

If anyone can help, THANKS :smile:

Ron

Maybe I should have used the words "air end".

Again I don't want to have to buy one with a motor, or an A/C compressor unit.

Thanks for any links or information.
 
  • #3
You haven't really told us anything about what you are trying to do...

What are you compressing? What voume and pressure do you want?
 
  • #4
Hi RonL. I generally look for things like this at ThomasNet:
http://www.thomasnet.com/
Be prepared to make some phone calls too. You can do a search but with the more complex things such as compressors, you're better off calling and talking to a sales person live.

Thomas Register used to have a line of green books that looked like a set of encyclopedias. They'd come out once a year and cost a small fortune. Now with the internet, that line of books has gone away and replaced by the ThomasNet web site. There are others like it such as GlobalSpec.com but I'm kinda partial.
 
  • #5
Whoa. I completely forgot about the old Thomas books.
 
  • #6
Yea, the Thomas books were like the internet on paper. They were so expensive, and so valuable, that when some department bought a new set, the old ones could be auctioned off to subsidize the new set.

Alas, they've now gone the way of the slide rule.

I'm not complaining though, mind ya. :tongue2:
 
  • #7
Thanks Russ, Fred, Q,

I have seen scroll compressors in books in the past, but the mind could not quite grasp the operation, a link in some other thread took me to wiki, where they showed an animation of operation, the mention of no need for valves or lubrication in some cases, gave me reason to look at these compressors opposed to vane units.

I have two vane motors that are rated at just under 5 HP, RPM 3,000 and if I remember correctly 14 CFM@ 100 PSI. These require some method of lubrication, which poses some unknowns for me. These motors are quite small and lite, when compared to most other things in the 5HP range. I would like scroll units somewhat like these.

As for the Thomas directories, I do have two old sets that I picked up from the main branch of the Austin library many years ago (they were updating, and selling off old books) like PF they take up a lot of time.:biggrin: They always seem to be behind something, and too much trouble to dig out. Their best service so far has been holding up 4 other shelf boards.:rolleyes:

This is still in relation to an energy system that I am working on, both In my mind and physically. Due to the size of my system tanks (largest is 250 Gallon) my bobcat has had to give up it's seat on the trailer:rofl:.

I'm keeping most of this separate from my real goal of having a propane based heat absorption unit. My knowledge is building thanks to PF, just not at the pace I had hoped for, I'm back home for a while and hope to get caught up, and back on track as soon as I can figure out where the track is.:confused:

Russ, as for the PM on the lead acid battery, that is still on the back burner and I have the components to work on a prototype, looks like prep work for father's day has taken first place, so my questions will come some time after that.

Thanks All

Ron
 
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  • #8
russ_watters said:
You haven't really told us anything about what you are trying to do...

What are you compressing? What voume and pressure do you want?

To answer a little of this question, the compression of two materials, one air and the other propane vapor, the propane is a closed system and enclosed in a tank. Air is drawn into the same tank and compressed but kept isolated from the propane, and then exhausted at a colder temperature. (100 F degrees in, and 33 F out) air flow volume determines KW output.

The working of this design will focus on a single power shaft, which involves 4 or more (vane or scroll) units plus a generator that serves as both a drive motor if needed at any time, and a method of extracting power, which is needed to equal out the change in temperature of the air that flows through the system.
I would like high pressure which would reduce size, but around 100 psi keeps things at a safer level.

The basis that I'm working on is, all mechanical work takes place inside the cold reservior, which moves heat of compression and frictional heat into a cold propane liquid, which in turn raises propane gas pressure (waste heat is always recycled).

The use of two drive units (air and propane) and two scavaging units with a length of tubing and check valves of proper pressure ratings between them will assure that pressures stay at proper levels.

An insulated inner tank will serve the need of two levels of pressure and temperature in the propane portion of the system.

Again as said before in another thread, the most important goal of this design is lots of cold air, the electrical output keeps the system from overheating.
I think what's different here is the intake and discharge are interacting with just one reservior. It's easy to get lost inside and hard for me to put into words, but it is kinda like the dog that chases his tail and never catches it.:smile:
 
  • #9
Q_Goest said:
Hi RonL. I generally look for things like this at ThomasNet:
http://www.thomasnet.com/
Be prepared to make some phone calls too. You can do a search but with the more complex things such as compressors, you're better off calling and talking to a sales person live.

Thomas Register used to have a line of green books that looked like a set of encyclopedias. They'd come out once a year and cost a small fortune. Now with the internet, that line of books has gone away and replaced by the ThomasNet web site. There are others like it such as GlobalSpec.com but I'm kinda partial.

I found a little information on a base mount unit that is v belt driven, all data is about the same as the vane motor, but at 49 pounds it is almost three times as heavy as the same 5 hp vane motor and almost twice as large.
Having the option of a dual output shaft on the vane motors will let me set them in a straight line, and have a more compact configuration.

Thanks for the help:smile:
 
  • #10
Well my AC friend finally delivered two 5 ton rated scroll compressors, they appear to be small in diameter(which is good) and are quite heavy, hopefully it is in the shell and motor weight. I will need to disect them carefully, in order to use the portion of the shell they are mounted in. I'm trying to decide between using a disc grinder (messy and more pron to be dangerous) or a metal cutting band saw (will have to build a jig and rotate the shell two or three times) much slower.

And then there is the smokey cutting torch.:uhh::frown:

Have any of you guy's done this before?

Anyone with any information please speak up.:smile:

It always amazes me how many times threads are viewed and no one comments in any way.
I'm not just talking about my post and threads.

Ron
 
  • #11
Some good news, I found what seems to be the main market for scroll compressors, the two that I have are Copeland refrigeration units (57,000 and 61,000 BTU) the spec tag says the rating for pressure is 20 bars, this just might compensate for the extra weight.

I have decided to set up a lazy suzan style turntable on my work bench and build a solid mount for an angle grinder, then separate the base from the shell, just above the internal motor mount, which will allow the motor to drop out. Depending on my design options the two shells will be clamped togeather forming a dual air end unit.

As best I can tell the coupling between the motor shaft and the compressor unit appear to be a slip fit, something like a Lovejoy flex coupler.

After this weekend maybe I can put some time in on this project.:smile:

Ron
 
  • #12
Tell me how it works out! And please post pictures!
 
  • #13
chayced said:
Tell me how it works out! And please post pictures!

Thanks, I will :smile:
 
  • #14
RonL said:
To answer a little of this question, the compression of two materials, one air and the other propane vapor, the propane is a closed system and enclosed in a tank. Air is drawn into the same tank and compressed but kept isolated from the propane, and then exhausted at a colder temperature. (100 F degrees in, and 33 F out) air flow volume determines KW output.

The working of this design will focus on a single power shaft, which involves 4 or more (vane or scroll) units plus a generator that serves as both a drive motor if needed at any time, and a method of extracting power, which is needed to equal out the change in temperature of the air that flows through the system.
I would like high pressure which would reduce size, but around 100 psi keeps things at a safer level.

The basis that I'm working on is, all mechanical work takes place inside the cold reservior, which moves heat of compression and frictional heat into a cold propane liquid, which in turn raises propane gas pressure (waste heat is always recycled).

The use of two drive units (air and propane) and two scavaging units with a length of tubing and check valves of proper pressure ratings between them will assure that pressures stay at proper levels.

An insulated inner tank will serve the need of two levels of pressure and temperature in the propane portion of the system.

Again as said before in another thread, the most important goal of this design is lots of cold air, the electrical output keeps the system from overheating.
I think what's different here is the intake and discharge are interacting with just one reservior. It's easy to get lost inside and hard for me to put into words, but it is kinda like the dog that chases his tail and never catches it.:smile:

I have looked at this before and sometimes things just come into focus.

http://en.wikipedia.org/wiki/Maxwell's_demon

Maybe if I'm wrong someone can say why.

If one scrolls down the page to experimental work by David Leigh, it seems that his work is much like what I'm building, where two gases exchange energy and the generator serves the demon function. He used light, I'm drawing heat from the atmosphere.

I'm not sure, based on very little response, that anyone really understands what is described above in my system. The view count has been pretty high. (Imo)

Time is flying and I'm missing my golden opportunity, the temperatures here are triple digets (103 yesterday) Too hot to work outside.:yuck:
 
  • #15
Scroll compressors can go up to 7-8 bar (atm) so one might be enough. They have a very good m3/min depending on size and can work even without lubrication ( bit more expensive).

If the sole purpose is cold air then the propane seems useless. Use water instead to absorb the heat.
 
  • #16
Lok said:
Scroll compressors can go up to 7-8 bar (atm) so one might be enough. They have a very good m3/min depending on size and can work even without lubrication ( bit more expensive).

If the sole purpose is cold air then the propane seems useless. Use water instead to absorb the heat.

The sole purpose is not just cold air, the propane and electricity is how such an extreme difference of high and low temperature can be defined within a single cold reservior. The power and pressure differences are worked through the air motors as both, compression and expansion devices.

My thinking might be flawed as to which is best in the long run, I shy away from water because of ice, and the fact that in steam range (might be best) heat tends to move out of the system.

Propane gives the added value of drawing in heat from the atmosphere as well as absorbing the waste heat of compression, when in it's low temp state.
IF NEEDED, it can contribute to the heat value of the system, as it is a combustion type fuel.

The fact that so many forms of stored energy can be designed inside the cold reservoir, steam could in fact come into play in the system as an intermediate power provider. The overall goal is to pull air in at a higher temp and discharge it at a much colder state.

The fact that this refocus of waste heat (of compression) into a driving power, let's the final facts come out to three things,

A. BTU's removed from total air flow.
B. Water drop out from condensation.
C. Electrical Wattage (output) equal to sum of BTU removed from air.

Ron

P.S. The copeland specs on the side of the compressor states a 20 bar max pressure (it is a scroll)
 
  • #17
RonL - Did you have any luck locating a scroll compressor (only) unit? I have a similar project? If so, can you point out the solution for me?

Big thanks in advance,
 
  • #18
franko9 said:
RonL - Did you have any luck locating a scroll compressor (only) unit? I have a similar project? If so, can you point out the solution for me?

Big thanks in advance,

So many things change my focus with the greatest of ease, so no I have not gone beyond where I was in post #11.
The big holdup...? I simply can't make a decision about how and exactly where to cut the housings so that I can still use the end sections and not ruin the critical alignment of the scroll unit.
Work and other factors have been the main cause of the project setting in a paused condition, but it is still in the plan for what I want to do.

Thanks for asking, it will be a good motivator.

Ron

PS in searching the net I did see some units in designs that mount solid and a motor is added using belt and pully.
These were physically the wrong shape and size for what I want to do.
 
Last edited:
  • #19
Back when Trane had engineers in the USA (now in India), I used to work there. Being in the environment, gave me some insider knowledge on compressors, including the scroll. All compressors need predigious lubrication. In the reciprical types, the oil settles to the bottom of the compressor housing and gets drawn up through an angled hole in the shaft.
I'm not certain how the oil gets drawn into the scrolls working area, BUT it's absolutely essential that it's soaking in oil. The oil forms the gas-tight seal and, it gets between the metal peices, preventing them from rubbing.
In and AC/Heat pump, oil mist is continually leaving the compressor and getting mixed up with the refrigerant, but the cycle has a preference for bringing oil back to the compressor, so it doesn't dry out.
If you reverse the process and use the compressor as a generator (which a scroll can do for awhile - if properly modified) then the oil will tend to settle outside the compressor, and eventually you run dry. Shortly after that, your scroll self detructs (had experience with this during R&D).
Now vacuum people have another type of scroll that runs dry. It uses graphite surfaces that wear together and shortly need to be replaced. These puff microscopic carbon powder instead of the oil you see with most vacuum pumps.
 
  • #20
Mike_In_Plano said:
Back when Trane had engineers in the USA (now in India), I used to work there. Being in the environment, gave me some insider knowledge on compressors, including the scroll. All compressors need predigious lubrication. In the reciprical types, the oil settles to the bottom of the compressor housing and gets drawn up through an angled hole in the shaft.
I'm not certain how the oil gets drawn into the scrolls working area, BUT it's absolutely essential that it's soaking in oil. The oil forms the gas-tight seal and, it gets between the metal peices, preventing them from rubbing.
In and AC/Heat pump, oil mist is continually leaving the compressor and getting mixed up with the refrigerant, but the cycle has a preference for bringing oil back to the compressor, so it doesn't dry out.
If you reverse the process and use the compressor as a generator (which a scroll can do for awhile - if properly modified) then the oil will tend to settle outside the compressor, and eventually you run dry. Shortly after that, your scroll self detructs (had experience with this during R&D).
Now vacuum people have another type of scroll that runs dry. It uses graphite surfaces that wear together and shortly need to be replaced. These puff microscopic carbon powder instead of the oil you see with most vacuum pumps.

Thanks Mike,
Some of that kind of information is so hard to find and dig out, I did find a little about the dry running units and the information sounded like the longer they ran the better the seal, which is what you said, but no indication about how quick repair or replacement have to happen.

You have read this thread and maybe others, in a closed design I see no real problem using propane as a refrigerant, do you know of a lubricant that would work well and not dilute too much? I'm not sure how, but I think distribution and recovery are things that can be designed for, without too much effort. Any advise or thoughts?

Thanks
Ron
 
  • #21
Refrigerants and lubricants are typically chosen to be readily dissolve into one another and yet be non-reactive chemically. Mineral oil would probably work great with propane.

After selecting some lubricant and refrigerant, a thick walled test tube is used to perform an accelerated compatibility test. A sample of each material found in the compressor, mild steel, spring steel, copper, insulated copper, plastic from the motor, is placed in the tube along with a sample of the lubricant. The tube is sealed to a high vacuum system - perhaps using a turbo pump or liquid nitrogen to get a very low vacuum (less than .1mT). Then, the refrigerant is added to the tube by cooling it with liquid nitrogen. Afterwards, the tube is flame sealed.

Any number of these tubes are placed in thick-walled steel vessels and baked at 200C for a few months. It's not unusual for the tubes to explode due to the pressure, so they need to be kept separate and very heavily covered.

After a few months, the tubes are cooled and studied for signs of corrosion, color change, etc.

Water and dirt is a bad thing in the system. And yet it often resides in home air conditioners due to poor discipline, disinterest, or lack of education on the part of the personnel that install the plumbing and oversee the construction. Typically water will destroy the compressor within the warrantee period.

Reverse operated scroll breaks down quickly, so check valves are typically used to keep the back pressure from starting them operating backwards. If one achieves sufficient speed and becomes powered, it will continue to turn backwards.

I also know that during normal operation both scroll and recips were pretty wet with oil. These machines were taken in gaseous refrigerant and expelling much hotter gaseous refrigerant, so having the refrigerant wash out the oil wasn't so much a problem.

What may be a problem is where the oil tends to accumulate. In these machines, it tends to splatter and splash and some will leave the compressor as a mist. Eventually, the mist dissolves into the condensed liquid refrigerant and goes on to the expansion valve, evaporator, and back to the compressor. Pretty much, it is a straight shot back into the compressor and it tends to be much harder to leave.

If you're boiling off refrigerant - like in a generator, I imagine the oil's going to accumulate where the refrigerant is boiling. That would create a bad situation for the compressor (now generator) because the boiler is effectively acting as a distillery and sending back dry, clean gas.

Perhaps in that case, a small portion of the liquid from the boiler could be continually sent to the compressor and evaporated there, thus allowing the oil to have a return path.

I hope this helps a bit,

Best Regards,

Mike
 
  • #22
Mike_In_Plano said:
Refrigerants and lubricants are typically chosen to be readily dissolve into one another and yet be non-reactive chemically. Mineral oil would probably work great with propane.

After selecting some lubricant and refrigerant, a thick walled test tube is used to perform an accelerated compatibility test. A sample of each material found in the compressor, mild steel, spring steel, copper, insulated copper, plastic from the motor, is placed in the tube along with a sample of the lubricant. The tube is sealed to a high vacuum system - perhaps using a turbo pump or liquid nitrogen to get a very low vacuum (less than .1mT). Then, the refrigerant is added to the tube by cooling it with liquid nitrogen. Afterwards, the tube is flame sealed.

Any number of these tubes are placed in thick-walled steel vessels and baked at 200C for a few months. It's not unusual for the tubes to explode due to the pressure, so they need to be kept separate and very heavily covered.

After a few months, the tubes are cooled and studied for signs of corrosion, color change, etc.

Water and dirt is a bad thing in the system. And yet it often resides in home air conditioners due to poor discipline, disinterest, or lack of education on the part of the personnel that install the plumbing and oversee the construction. Typically water will destroy the compressor within the warrantee period.

Reverse operated scroll breaks down quickly, so check valves are typically used to keep the back pressure from starting them operating backwards. If one achieves sufficient speed and becomes powered, it will continue to turn backwards.

I also know that during normal operation both scroll and recips were pretty wet with oil. These machines were taken in gaseous refrigerant and expelling much hotter gaseous refrigerant, so having the refrigerant wash out the oil wasn't so much a problem.

What may be a problem is where the oil tends to accumulate. In these machines, it tends to splatter and splash and some will leave the compressor as a mist. Eventually, the mist dissolves into the condensed liquid refrigerant and goes on to the expansion valve, evaporator, and back to the compressor. Pretty much, it is a straight shot back into the compressor and it tends to be much harder to leave.

If you're boiling off refrigerant - like in a generator, I imagine the oil's going to accumulate where the refrigerant is boiling. That would create a bad situation for the compressor (now generator) because the boiler is effectively acting as a distillery and sending back dry, clean gas.

Perhaps in that case, a small portion of the liquid from the boiler could be continually sent to the compressor and evaporated there, thus allowing the oil to have a return path.

I hope this helps a bit,

Best Regards,

Mike

Thanks Mike,
I believe that will be a lot of help, it will take several readings, a lot of thought and consideration, but I think after a while I will understand what can and can't be done and why.
Thank you very much.

Ron
 

1. What is a scroll compressor?

A scroll compressor is a type of positive displacement compressor that compresses air or gas by using two spiral-shaped scrolls. One scroll remains stationary while the other orbits around it, creating a series of gas pockets that decrease in volume and increase in pressure as they move towards the center.

2. What are the advantages of using a scroll compressor?

Scroll compressors have several advantages, including quiet operation, high efficiency, and low maintenance. They also have fewer moving parts compared to other types of compressors, making them more reliable and durable. Additionally, scroll compressors have a smaller footprint and are more lightweight, making them ideal for use in limited space applications.

3. What are the specifications of a scroll compressor?

The specifications of a scroll compressor can vary depending on the manufacturer and model. However, some common specifications to consider include the compressor's maximum pressure, flow rate, power requirements, and noise level. It is important to choose a compressor with specifications that meet the specific needs of your application.

4. How does volume and pressure affect a scroll compressor?

The volume and pressure of a scroll compressor are closely related. As the volume of gas decreases in the compressor, the pressure increases. This is due to the compressor's unique design that traps and compresses gas in a smaller space. The higher the pressure, the more compressed the gas becomes, resulting in increased energy efficiency and performance.

5. What are some common uses for scroll compressors?

Scroll compressors are commonly used in various applications, including air conditioning and refrigeration systems, heat pumps, and industrial processes. They are also used in medical equipment, such as oxygen concentrators, and in automotive air conditioning systems. Their high efficiency and compact size make them ideal for use in residential, commercial, and industrial settings.

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