Quincy Rotary Question

[Doubled33]

I am in need of a new / new to me compressor. I am in a remote location and priced a new QR 340 and fell over at the 10K number.

The used market is almost non existent.

There is a local used low pressure QSLP 15 rotary compressor for sale.

I have two questions.

Can it easily be converted to produce say 125 or more PSI?

Can the motor be changed to 10hp single phase and have less CFM? Basically is this like the piston compressors where the rotary screws have a HP range they work in?

 

[Walkers]

I wouldn’t count on it, mostly since it is a series designed for low pressure. Most likely you would have to change so many components as to make it not worthwhile.

 

[NOEYEZ]

I am in need of a new / new to me compressor. I am in a remote location and priced a new QR 340 and fell over at the 10K number.

The used market is almost non existent.

There is a local used low pressure QSLP 15 rotary compressor for sale.

I have two questions.

Can it easily be converted to produce say 125 or more PSI?

Can the motor be changed to 10hp single phase and have less CFM? Basically is this like the piston compressors where the rotary screws have a HP range they work in?

 

[MacMcMacmac]

Some of the smaller Quincy encapsulated screws used the same air end running at different rpm. The top end of the range was hitting near on 10k rpm before the next size up went to a bigger frame. You can be sure this compressor is geared to pull the maximum HP out of whatever motor is attached to it, so putting on a smaller motor is probably not going to work even at low pressure, let alone trying to get full 125psi performance out of it. This is more of a blower than compressor.

 

[BarrelRoll]

Shoot I was just over at our water treatment plant with a high flow low pressure Quincy. I haven't looked at what makes it high flow low pressure. I'm thinking it's not just adjusting the pressure switch and pilot valve. When I worked on compressor full time Sullivan Palatek were rock solid machines we joked were built out of a Grainger catalog, parts were very easy to come by. I take care of a dozen atlas copcos now and wouldn't buy one, the smaller machines are ok thought he bigger machines all have issue. There's no reason for a digital controller on a rotary screw machine besides to cost you more money.

 

[Walkers]

On thinking about this, you could probably go to the quincy site, look for the parts list for that compressor, get the p/n for that air end, then look to see if it is used on any higher pressure units.

 

[MacMcMacmac]

It might be, however, it will be geared appropriately for the higher pressure and horsepower requirements. Usually, low pressure, high flow compressors have oversized air ends to move a large volume of air for a given horsepower. If you want higher pressure at the same, or lower HP, you are going to have to gear down that air end by quite a lot, even if the gears exist, which they probably don't. It's not a simple as putting a bigger or smaller pulley on a recip. Most screws rotational speeds are governed by a fixed gear ratio in the gearbox, unless driven by a VSD or directly coupled to the motor shaft. The screw will also lose most of its efficiency if used below its minimum designed rpm.

The only way I could see this project being worthwhile is if you had access to a 10hp airend and had the skill to install it, since you already would have all of the supporting equipment to operate it. Not impossible, but it would be an undertaking for sure. You could always belt drive it if necessary.

 

[Doubled33]

On thinking about this, you could probably go to the quincy site, look for the parts list for that compressor, get the p/n for that air end, then look to see if it is used on any higher pressure units.

I tried this. I found a catalog but not sure it was the correct one. There is also a high probability I did not know what I was looking for.

 

[Doubled33]

It might be, however, it will be geared appropriately for the higher pressure and horsepower requirements. Usually, low pressure, high flow compressors have oversized air ends to move a large volume of air for a given horsepower. If you want higher pressure at the same, or lower HP, you are going to have to gear down that air end by quite a lot, even if the gears exist, which they probably don't. It's not a simple as putting a bigger or smaller pulley on a recip. Most screws rotational speeds are governed by a fixed gear ratio in the gearbox, unless driven by a VSD or directly coupled to the motor shaft. The screw will also lose most of its efficiency if used below its minimum designed rpm.

The only way I could see this project being worthwhile is if you had access to a 10hp airend and had the skill to install it, since you already would have all of the supporting equipment to operate it. Not impossible, but it would be an undertaking for sure. You could always belt drive it if necessary.

Thanks for this. Definitely more than I want to deal with. It is not beyond my skill set, but beyond my knowledge level of these compressors.

 

[Packard V8]

I am in need of a new / new to me compressor. I am in a remote location and priced a new QR 340 and fell over at the 10K number.

The used market is almost non existent.

There is a local used low pressure QSLP 15 rotary compressor for sale.

I have two questions.

Can it easily be converted to produce say 125 or more PSI?

Can the motor be changed to 10hp single phase and have less CFM? Basically is this like the piston compressors where the rotary screws have a HP range they work in?

FWIW, 10hp single phase motors are almost non-existent and high dollar, plus usually requires an industrial transformer supply. Are you saying you have no access to three phase power, but still need a big compressor?

What is your remote location? If you can get three phase, we've got a rebuilt 25hp Kaeser rotary which needs a good home and will make you a heckuva deal.

jack vines

 

[Doubled33]

FWIW, 10hp single phase motors are almost non-existent and high dollar, plus usually requires an industrial transformer supply. Are you saying you have no access to three phase power, but still need a big compressor?

What is your remote location? If you can get three phase, we've got a rebuilt 25hp Kaeser rotary which needs a good home and will make you a heckuva deal.

jack vines

I have access to a 10hp single phase but not my first choice. Power here is .45 per kWh.

I need over 20 cfm to run a blast cabinet at my house. I only have single phase but have a meter upgrade so I have plenty of amps.

I have an air dryer that is good for almost 40 cfm.

My current set up was a Curtis 7.5, but got dropped in shipping and crushed and bent a lot of things. I am on day 70 of moving insurance but that is another story. I will get pennies on the dollar.

Blasting is a hobby as I have an restoration project of a S1 E type. I have blasted off an on all my life for my use and helped alot of others. Bottom line is not an income source and have to be diligent on budget.

I am in Hawaii. We have a Quincy and IR place on island.

Thanks for the offer on the big machine.