GardnerDenver Compressor

[ColoradoDoug]

I'm looking at a GardnerDenver screw type compressor and had a few questions. The seller stated that the motor was 460v. I've seen others for sale that show 230v. Do most of these motors have the option of 230 or 460v? Would the 30hp be downrated with 230v? What are common wear points or problems to look for with a screw type compressor like this? Anything else to look for? The price is pretty good. Are they normally quieter than a normal rotary style compressor, or louder? I haven't really been looking for a screw type compressor, but I figure more is better and saw this one.

Sorry, it's a model EBERGD.

 

[Canadian Cowboy]

A screw compressor will be a 3 phase motor not single phase the voltage/voltages will be stamped/printed on the electrical motor name plate example 208/230/460
If only one voltage is stamped on the plate than the motor will only work on that one voltage.

CC

 

[Canadian Cowboy]

The auction listing states 208v only if that is the actual case and you have 460v than you would a step down transformer big enough to handle the motor amperage draw.

CC

 

[EOC_Jason]

^^^ You will have to check the plate on the motor to see what it can be wired to use. Likewise the motor starter you might have to adjust or change components.

Most of the cost in a screw compressor is the air-end. You need to see if they have a maintenance log. Oil filter & separator are changed every 2-3 months usually, and oil is changed annually (approx). You also need to find out how many hours are on the unit. The air end has a finite life span and if it's getting close to that time to replace it then you are going to be spending a lot of cash in addition to the compressor purchase.

Another thing to check is you are wanting a certain HP at a certain voltage. Make sure your breaker panel can support the size breaker you will be needing.

 

[koditten]

Unless you are going to use this machine in an industrial environment, you will not be getting a deal at any cost. Rotory screw machines are designed to run constantly.

What is the CFM of this unit?

Unless the machine has logged maintanance records that show that oil changes have been done properly, I would steer clear.

I work with rotory screw compressors everyday, the only thing I would use one for would be if I had to run a sand blaster...alot

I guess it would help to know what size of shop you have.

I know there are some small units out there that might serve a home owner, but I have not dealt with them.

I run and service the things every day and I love them, but I would not want one for my own shop.

Plusses

Unlimited air supply
fairly quite
Few moving parts
Used ones are cheap
proper maintanace equals ulimited lifetime. I have a quincey that has been running since 1994 with shut downs for maintanace only.

Minuses

Pay for electricity if you are using 10 cfm or 30 cfm, the cost is close to the same because motor is running all the time
Yearly oil and filter changes, quarterly on air filter.
Need to run for a long time to get up to operating temps or maintance issues will arise.
Most require 3 phase power

These are a few off the top of my head, there are others, but i think you get the idea.

Later

KO

 

[alan camby]

I'm looking at a GardnerDenver screw type compressor and had a few questions. The seller stated that the motor was 460v. I've seen others for sale that show 230v. Do most of these motors have the option of 230 or 460v? Would the 30hp be downrated with 230v? What are common wear points or problems to look for with a screw type compressor like this? Anything else to look for? The price is pretty good. Are they normally quieter than a normal rotary style compressor, or louder? I haven't really been looking for a screw type compressor, but I figure more is better and saw this one.

Sorry, it's a model EBERGD.

Some motors are able to run on 230 or 460 3 phase and some are voltage specific. If the motor will run on 230 then the HP would be the same as if it ran on 460. The amperage will be about double for the 230 option though.

Like already mentioned, the machine might have been spec-ed out to be a 460 machine. Motor might be able to be wired 230 but the contactors, and wiring might not be able to handle the higher current. Control transformer might not be multi voltage either.

If you think you can run this machine at home forget it. I assume you want to put this in a factory or a shop that has 3 phase.

 

[Bob C]

Unless you are going to use this machine in an industrial environment, you will not be getting a deal at any cost. Rotory screw machines are designed to run constantly.

What is the CFM of this unit?

Unless the machine has logged maintanance records that show that oil changes have been done properly, I would steer clear.

I work with rotory screw compressors everyday, the only thing I would use one for would be if I had to run a sand blaster...alot

I guess it would help to know what size of shop you have.

I know there are some small units out there that might serve a home owner, but I have not dealt with them.

I run and service the things every day and I love them, but I would not want one for my own shop.

Plusses

Unlimited air supply
fairly quite
Few moving parts
Used ones are cheap
proper maintanace equals ulimited lifetime. I have a quincey that has been running since 1994 with shut downs for maintanace only.

Minuses

Pay for electricity if you are using 10 cfm or 30 cfm, the cost is close to the same because motor is running all the time
Yearly oil and filter changes, quarterly on air filter.
Need to run for a long time to get up to operating temps or maintance issues will arise.
Most require 3 phase power

These are a few off the top of my head, there are others, but i think you get the idea.

Later

KO

Good Info. Let me add a plus to your list.

HEAT, The aftercooler is probably pushing around 160 degrees F, you paid for it, why not vent it thru your shop in the winter time.

 

[930dreamer]

Post some pics and hp from the motor.

 

[ColoradoDoug]

I think I'll pass on it. My knowledge of the screw typ compressors is very limited, that's why I asked. I'm not concerned about the 3 phase portion, but I don't want to have it run all of the time. I have my eye on a couple Quincy compressors as well that I may look at picking up.

Thanks

 

[Bob C]

I think I'll pass on it. My knowledge of the screw typ compressors is very limited, that's why I asked. I'm not concerned about the 3 phase portion, but I don't want to have it run all of the time. I have my eye on a couple Quincy compressors as well that I may look at picking up.

Thanks

Yup, all screws perform best at 100% duty full load wide open. I seriously doubt you could max it's delivery flow.

 

[pop pop]

Plus the air will have more oil contamination than other types of compression.

 

[koditten]

I forgot about that. Screw compressors make water as well as compressed air and it doesn't sit at the bottom of the tank. It goes straight out to point of use.

KO

 

[Bob C]

Plus the air will have more oil contamination than other types of compression.

Not necessarily true. Screws are oil flooded, however a properly maintained screw will deliver less parts per million oil to air than a typical reciprocating compressor. I have multiple screws in critical arenas such as breathing air in a foundry, food processing in a chees mill, air bubbling in a plant that deals with fructose syrup and I have 4 vacuum screws in a meat plant where they **** the meat thru pipes. Granted all of these layouts require food grade and breathing filters dor very fine filtration.

See, in a screw, the oil performs 4 functions.
1.) "Lubrication" of the screws and associated parts
2.) "Sealing" between the screws as they are only thousandths of an inch apart.
3.) "Cooling" as the oil carries the heat thru an oil aftercooler to be removed from the oil.
4.) "Cleaning" of any foreign particles that get past the intake filter. These are carried to the oil filter for collection.

As the air has passes thru the screws it is mixed with oil and passes thru the seperator that removes the oil from the air. Here is where the oil is returned to the sump and the air continues on it's way. Seperators are suprisingly efficient in oil removal. Much better than recips.

There are many configurations of oil and compressed air flow thru a screw. what I described is just a basic setup.

 

[Bob C]

I forgot about that. Screw compressors make water as well as compressed air and it doesn't sit at the bottom of the tank. It goes straight out to point of use.

KO

In some applications, this technically is correct. A proper system layout for water collection and containment is necessary.

In a tank setup, the air/water mix is sent to a storage tank first. If this is piped in a certain fashion, it can be a VERY GOOD seperator of the water because we are going to use the high pressure forced air flow of the screw compressor. Remember it pushes air like a jet engine.

Lets say our discharge line off the screw is 2" and our tank is a 400 Gallon vertical with 3" inlet hole 2 feet from the bottom. Install a street elbow on the inside of a double tapped hex bushing and install the bushing in the tank. Have the street elbow horizontal to the floor. Connect your discharge line to the bushing. Connect the shop air system to an outlet near the top of the tank. (much harder for water to rise)

Now, when the discharge air/water mix passes thru the bushing, it will be redirected into a cyclone in the tank like a centrifuge. The heavy water will be rung out to the tank's sidewalls and drop to the bottom for collection in the water containment system. This takes the bulk of the water away before the water seperator filters and dryer.

 

[koditten]

Well said , Bob, but I think we are off topic now. You are turning this thread into work, because it is exactly what I have to deal with every day

KO

 

[Bob C]

Well said , Bob, but I think we are off topic now. You are turning this thread into work, because it is exactly what I have to deal with every day

KO

Sorry bout that.

 

[pop pop]

We had two early (70's) Pac Air screws from IR @ 300 hp each. Maybe the set up wasn't so good cause we got lots of oil carry over and multiple motor failures. Never wanted another. We didn't have any oil separation on the recips and got little oil. Had one 600 hp Fuller vane that pumped a lot of oil until we learned how to operate it better.