To avoid these ads, REGISTER NOW!

3 phase screw air compressor on a vfd thoughts?

G

Grant Gunderson

Well-known member
Joined
May 17, 2013
Messages
2,306
Location
Bellingham, WA
Been looking for a 5hp single phase unit but they are extremely expensive. Found a 7.5 hp used Quincy but it’s 3 phase. Any issues running one on a vfd?

It’s more compressor than I need but price is right.

Thoughts?

I’m aiming for screw do to noise levels.

My other option is most likely a Chinese option given my budget. Most of the year I have low air demands. 4 months a year I’ll need. 105 psi at 14cfm
 
To avoid these ads, REGISTER NOW!
B

Beerhippie

Well-known member
Joined
Oct 13, 2023
Messages
9,490
Location
Far NE Oregon
Due to the maintenance requirements of a screw comp, I'd shy away from used--but that's just me.

If they have maint. records for it, that would make me more comfortable. Check the cost of a maint. kit and frequency of maint. before buying--you might find that a deal-breaker.

Our IR screw needs oil and filters about once a year--@ $800 for the kit.
 
U

u3b3rg33k

Well-known member
Joined
Dec 18, 2017
Messages
4,038
Grant Gunderson said:
Been looking for a 5hp single phase unit but they are extremely expensive. Found a 7.5 hp used Quincy but it’s 3 phase. Any issues running one on a vfd?

It’s more compressor than I need but price is right.

Thoughts?

I’m aiming for screw do to noise levels.

My other option is most likely a Chinese option given my budget. Most of the year I have low air demands. 4 months a year I’ll need. 105 psi at 14cfm
Click to expand...
I wouldn't shy away from it personally but I love slapping VFDs on things.

used VFDs are a thing btw. I'd rather grab a name-brand used unit of the *bay than a no-name brand, every day of the week and twice on sunday. just grab a 10HP rated drive for your 5HP load - that's the rule of thumb if you wanna single-phase inlet a drive.
 
OP
G

Grant Gunderson

Well-known member
Joined
May 17, 2013
Messages
2,306
Location
Bellingham, WA
American Locomotive said:
The only issue will be dealing with the controls (if it has any). You can't just hook a VFD up to the cord and have it work. The VFD has to go directly to the motor, and nothing else.

Your air demands are pretty low. You should be able to find a true low-RPM 5HP reciprocating compressor for that price.
Click to expand...
From e everyone I’ve talked to screws keep getting recommended due to noise as I have consensual offices directly bellow and next to it plus my sales floor too.
 
B

Beerhippie

Well-known member
Joined
Oct 13, 2023
Messages
9,490
Location
Far NE Oregon
Grant Gunderson said:
From e everyone I’ve talked to screws keep getting recommended due to noise as I have consensual offices directly bellow and next to it plus my sales floor too.
Click to expand...
It's not the style of compressor so much as the sound-proof enclosure that matters. Screws scream, recips sound like a continuous train wreck. With a good SP enclosure, both can be very quiet.

Visit a compressor sales room and check out the sound levels of some before making your decision. Recips are so much more wallet-friendly, maintenance-wise.
 
A

American Locomotive

Well-known member
Joined
Jan 8, 2017
Messages
10,916
Location
Rhode Island
Grant Gunderson said:
From e everyone I’ve talked to screws keep getting recommended due to noise as I have consensual offices directly bellow and next to it plus my sales floor too.
Click to expand...
Slow-turning recips will always have a low thumping sound that transmits through a structure - even slow turning ones. But slow ones really are pretty quiet. What kind of floor will the compressor be on?
 
OP
G

Grant Gunderson

Well-known member
Joined
May 17, 2013
Messages
2,306
Location
Bellingham, WA
Beerhippie said:
Due to the maintenance requirements of a screw comp, I'd shy away from used--but that's just me.

If they have maint. records for it, that would make me more comfortable. Check the cost of a maint. kit and frequency of maint. before buying--you might find that a deal-breaker.

Our IR screw needs oil and filters about once a year--@ $800 for the kit.
Click to expand...
I'm ok with maintence costs as long as we can do it in house. I'm having a hard time swallowing the 12-15K price tag for an even a small Kaiser / atlas Coiupo, etc is new. The Chinese units are still $7K and they are a total unknown.
jblnut said:
Consensual activities.
Click to expand...
haha. Ment to type Commercial office spaces, damn auto correct and greasy hands. I have a Law office and a PT clinic next door, an engineering consulting firm down stairs as well as the offices for the land lord.
Beerhippie said:
It's not the style of compressor so much as the sound-proof enclosure that matters. Screws scream, recips sound like a continuous train wreck. With a good SP enclosure, both can be very quiet.

Visit a compressor sales room and check out the sound levels of some before making your decision. Recips are so much more wallet-friendly, maintenance-wise.
Click to expand...
There isn't a single compressor shop within a reasonable distance, so doing my best via online research and chatting with a few shops via phone.
American Locomotive said:
Slow-turning recips will always have a low thumping sound that transmits through a structure - even slow turning ones. But slow ones really are pretty quiet. What kind of floor will the compressor be on?
Click to expand...
It's a brick building. Floor is 12x12 post and beam old growth fir, with 3x12 stringers every 12" and then 2x4 young and grove car decking. Was built in 1922 to be a car dealership.
IMG_9532.jpeg
Restroom is going in back corner along with a dedicated compressor closet. Closet is being built to spec soon as I buy the compressor. Sales area is behind me in the photo, it's all open, so trying to minimize noise as the compressor will power the Ski tuning equipment in the winter and I will still be doing bike services etc.

I'm stuck with 220 or using a phase convertor / VFD. There is 3 phase in a vault 20' behind the building in the alley but PSE wanted $150K to bring it in.
 
S

seber

Well-known member
Joined
May 31, 2016
Messages
4,185
Location
Deep East Tx.
I put a 15 hp screw compressor in the warehouse to feed a machine in an isolated area. The warehouse manager complained so loud and to so many that I finally had to build a sound enclosure around it. You could still hear it at the other end of the warehouse. Nothing quiet about a screw compressor.
 
To avoid these ads, REGISTER NOW!
T

txvwnut

Well-known member
Joined
Jan 1, 2015
Messages
7,570
Location
Bedford, Texas
Screw compressors are nice and are fairly quiet(a whisper compared to the Saylor Beall I replaced) but still make noise, most of the ones I've seen run non-stop not cycle on off like a piston comp. I bought an Ingersoll-Rand screw for the day job and it runs non-stop only cycling a bleed valve for when air is needed.
 
C

cannuck

Well-known member
Joined
Nov 30, 2021
Messages
4,568
Location
Rural SK
Speaking of screw compressors: those young and groove ladies in the consensual office are actually massage therapists, right?

On to the shop floor: agree with others that a 7.5 is going to need to feed its 208 out phase converter from at least a 40A breaker on your 220 panel to handle starting loads You might want to look at a compressor that starts unloaded if power requirements are tight. But, if you have a welder circuit you probably have a 50A going out on 6 Awg you could share if box space tight (now get your minds out of the gutter!) Also suggest listening to what noise each compressor you are considering produces in the showroom - and also think about support down the road. Finally - for whatever compressor you are using you might want to seriously consider mounting it on an air bag suspended platform - as the wooden floor structure can be a giant musical instrument when that drum starts hammering.
 
OP
G

Grant Gunderson

Well-known member
Joined
May 17, 2013
Messages
2,306
Location
Bellingham, WA
Ok, If I go new budget rules out a new Kaiser screw or Atlas, etc. All are $12-15K.

If I go piston, Polar Air max $4600 but haven't found much for DB rarting.

Or

I could do the Eastwood Scroll. $2700 plus drier. However these seem to have issues, or at least the early models did.

Or

ABAC AS-3D Series Rotary Screw Air Compressor $4700 plus drier. Its made in Italy.​

I know nothing about ABAC, and am a bit concerned with potential service parts etc...

Once again, focused on noise levels over anything else.
 
OP
G

Grant Gunderson

Well-known member
Joined
May 17, 2013
Messages
2,306
Location
Bellingham, WA
cannuck said:
Speaking of screw compressors: those young and groove ladies in the consensual office are actually massage therapists, right?

On to the shop floor: agree with others that a 7.5 is going to need to feed its 208 out phase converter from at least a 40A breaker on your 220 panel to handle starting loads You might want to look at a compressor that starts unloaded if power requirements are tight. But, if you have a welder circuit you probably have a 50A going out on 6 Awg you could share if box space tight (now get your minds out of the gutter!) Also suggest listening to what noise each compressor you are considering produces in the showroom - and also think about support down the road. Finally - for whatever compressor you are using you might want to seriously consider mounting it on an air bag suspended platform - as the wooden floor structure can be a giant musical instrument when that drum starts hammering.
Click to expand...
HAHA, no, but I'm sure the ladies in the alley would trade a rub and tug for some fentanyl. Not familiar with Air bag platforms. have a link?
 
B

Beerhippie

Well-known member
Joined
Oct 13, 2023
Messages
9,490
Location
Far NE Oregon
txvwnut said:
Screw compressors are nice and are fairly quiet(a whisper compared to the Saylor Beall I replaced) but still make noise, most of the ones I've seen run non-stop not cycle on off like a piston comp. I bought an Ingersoll-Rand screw for the day job and it runs non-stop only cycling a bleed valve for when air is needed.
Click to expand...
That ain't right. You either have a massive leak or a seriously undersized comp for your purposes.

Under normal loads, our 5 hp IR screw runs less than a 30% duty cycle.
 
C

cannuck

Well-known member
Joined
Nov 30, 2021
Messages
4,568
Location
Rural SK
Grant Gunderson said:
HAHA, no, but I'm sure the ladies in the alley would trade a rub and tug for some fentanyl. Not familiar with Air bag platforms. have a link?
Click to expand...
start from bottom of home page https://rapidcontrol.com/goodyear/

- Video Search Results

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.
ca.video.search.yahoo.com ca.video.search.yahoo.com

In any case you would want to keep your sound enclosure fully in tact and just use 4 air bags for legs.
 
Last edited:
U

u3b3rg33k

Well-known member
Joined
Dec 18, 2017
Messages
4,038
FWIW i've got an Eaton 10HP V4 2 stage full package unit at work. very quiet. comes with a 15hp VFD so it can run on 1ø or 3ø.
only runs as fast as it needs to run to hold the setpoint you want. 1000hr service interval. I've got a 2 stage filter behind it and a refrigerated dryer.
 
T

txvwnut

Well-known member
Joined
Jan 1, 2015
Messages
7,570
Location
Bedford, Texas
Beerhippie said:
That ain't right. You either have a massive leak or a seriously undersized comp for your purposes.

Under normal loads, our 5 hp IR screw runs less than a 30% duty cycle.
Click to expand...
The compressor is designed to run continuously only bypassing air delivery until there is a demand, also this is a 25hp compressor. This isn't the only screw compressor I've seen that runs continuously either.
 
F

Firebrick43

Well-known member
Joined
May 12, 2015
Messages
13,897
Location
West central Indiana
Beerhippie said:
That ain't right. You either have a massive leak or a seriously undersized comp for your purposes.

Under normal loads, our 5 hp IR screw runs less than a 30% duty cycle.
Click to expand...
All the IR screws I have been around in manufacturing plants ran continuously. Or I should say at least one would, more come online as demand increases. They had a 500 gallon receiver, and really didn't like that even though it was in a compressor room due to the explosive potential energy it stored. Since there was air actuated hvac and facilities/plumbing demands of compressed air they ran all the time except Thankgiving and Christmas. They turned off the screws and relied on 3- 10hp compressors during those times.

u3b3rg33k said:
FWIW i've got an Eaton 10HP V4 2 stage full package unit at work. very quiet. comes with a 15hp VFD so it can run on 1ø or 3ø.
only runs as fast as it needs to run to hold the setpoint you want. 1000hr service interval. I've got a 2 stage filter behind it and a refrigerated dryer.
Click to expand...
I have a 5hp version without the intake silencer box and I can talk on the cell phone right next to it without the other person hearing or having issues hearing them.

I am sure with a decoupling mount, enclosure, and the silencer box it would but imperceivable to many.
 
Y

yaidunno

Well-known member
Joined
Feb 10, 2011
Messages
1,336
Location
WI
I picked up a Atlas G4FF a few years back after getting tired of listening to my piston pump run all the time while i was machining. Its a 5.5 hp single phase unit that had roughly 100 hours on the meter. It is remarkably quiet. All you hear is the cooling fan when its running. When the oil gets up to temp, the unit will continue to run for a bit with the compressor unloaded after it reaches its shut off PSI. This is done to bring the oil temp back down. A sizeable investment, but i'd do it again without a second thought. Its an awesome machine.
 
J

Jswain

Well-known member
Joined
Apr 26, 2013
Messages
2,449
Location
Calgary, AB
Get a big, used 3ph 7.5hp recip compressor(cheap because nobody wants 3ph) and run it off a cheap 10hp VFD - I used Mollom from amazon.
When your demand is low you can run it slow, even for 14cfm you won't need it full speed.
I installed mine in my home garage and I am much happier vs the 5hp single phase unit it replaced. Bonus when it kicks on I have the accel set to a few seconds so it no longer dims the lights from the big power draw. Super easy to program the VFD. I keep it at 50hz and it still produces more air, but much quieter & less heat.

I'm ~$800 CAD into mine, including the compressor, VFD, new drain valves fittings etc, & a valve rebuild kit.
 

Attachments

  • 1000011665.jpg
    1000011665.jpg
    1.4 MB · Views: 2
C

Chipm

Well-known member
Joined
Mar 10, 2020
Messages
410
Location
Georgia
I didn't know this was a thing. I am planning a new shop and ruled out rotary screw compressors because getting 3-ph will be cost prohibitive.
 
J

Jswain

Well-known member
Joined
Apr 26, 2013
Messages
2,449
Location
Calgary, AB
I always thought the same so I dismissed all the cheap used units over the years because they were 3ph and a new quality single phase motor is an arm and a leg.

I'll never look for a single phase compressor again. 7.5hp single phase was never really an option for me with the cold winter's / breaker sizing / startup amps. Now, no issues.
 
You must log in or register to reply here.
To avoid these ads, REGISTER NOW!
Top Bottom