Upgrade - Shop Air - Quality 60-80gal compressors?

[macardoso]

I just wanted to take a quick second to chime in and thank everyone for their insight! I'm going to be moving in a few months and will have the first opportunity to setup a "real" shop. I might be stopping by this thread to reread!

I do not have the volume or storage requirements that you guys do for my compressed air. I only feed my CNC with it for tool changes and use it to blow off chips. For me, noise was absolutely the most important factor since my current shop is in the basement of a 120 year old house and my wife and I can have a conversation at normal talking levels through the basement floor when she is sitting on the couch upstairs. I swapped my old 5Gal HF horizontal compressor for one of their "Ultra Quiet" models and boy what a difference it makes! I daisy chained the two compressors so I get 8 Gal of total storage. I can even leave them both plugged in so the old unit turns on under high demand.

2 Gallon 135 PSI, Ultra-Quiet Hand Carry Jobsite Air Compressor

Amazing deals on this 2Gal Ultra Quiet Jobsite Air Compressor at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

We can be on the second floor and barely hear it turn on (much quieter than the furnace), and it meets my limited air needs. Perhaps something for people to consider if they often switch on their big unit for small jobs that could be done with this guy.

 

[tq60]

Our champion has a 1700 rpm motor but very large pulley so compressor spins fast and is not quiet.

Ours is 7.5 hp.

The 5 hp version is mostly same but smaller pulley on motor.

Cheaper to use more common parts as bigger buy of source materials.

Does not run that long.

Most noise is related to air inlet as that is source of the popping like noise.

One of the many projects on to do list is to create sound dampening but that smacks of effort.

On previous compressor we added a pre pump that was like a vacuum cleaner pump to one inlet side and a offered air cleaner.

It made it more quiet and overcharged the inlet, like a super charger on an engine, reduced cycle time greatly as the primary stage no longer sucked air in but the valves allowed it to fill as the piston moved.

Reduced cycle time by maybe 1/2, that too is on the list by we need to monitor motor current to insure not pushing it

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[7milesup]

I swapped my old 5Gal HF horizontal compressor for one of their "Ultra Quiet" models and boy what a difference it makes! I daisy chained the two compressors so I get 8 Gal of total storage. I can even leave them both plugged in so the old unit turns on under high demand.

2 Gallon 135 PSI, Ultra-Quiet Hand Carry Jobsite Air Compressor

Amazing deals on this 2Gal Ultra Quiet Jobsite Air Compressor at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

We can be on the second floor and barely hear it turn on (much quieter than the furnace), and it meets my limited air needs. Perhaps something for people to consider if they often switch on their big unit for small jobs that could be done with this guy.

I have that same compressor. I purchased it for doing the trim in my new house. Used to have a Porter Cable pancake compressor for the same reason but absolutely hated how loud it was.
I have always said that I would never buy anything from HF but that Ultra Quiet compressor is awesome. It has become my go-to compressor, even in the shop as long as I don't need a large volume of air.

 

[FlyFishn]

I spent some time with a sales rep for a dealer today asking some questions. First off - I was correct about Fusheng Industrial taking over FS Curtis. It appears, from what the sales rep I spoke to said, that FS Curtis still does assembly in the US, but their motors and compressors are largely manufactured over-seas from existing designs. He did state that Champion was more likely to be mostly US-made where some of their motors may come out of Mexico or Brazil, as opposed to Asia.

On the subject of electrical requirements - his charts showed that a 5hp motor compressor is recommended to be on a 60a breaker and a 7.5hp motor is recommended to be on an 80a breaker. He also said that inrush, or starting, current could approach 2x full load amps.

There is going to be some headroom in the recommendations, for sure, but that is still high enough I am not sure I can get a compressor in the size range I am wanting to run on my circuit. I know from my load testing with my welder that the breaker will hold on in to the 40a range. As to how long it does is dependent on how high the draw is. Where at 43-45a the trip is pretty fast. If inrush/starting current on a compressor is under that with a running amperage closer to 30a then I may be able to squeeze by. Going off of the chart data that was provided, though, even a 5hp unit might be a tall order.

Going the other way - the chart data did point to a 3hp unit being capable to run on a 30a circuit. I don't think that is going to net me much more than I already have with my 20gal compressor. The motor on it is labeled as a 5hp motor, but it is a 110v unit that will run on a 15a circuit (I've done it, but a 30a runs it a lot better - no idea what the running amperage or inrush amperage is, I will have to load test and find out). So I don't think the motor is actually a 5hp.

Does anyone have any info on what size breakers they are running what size compressor motors - in the 3-7.5hp range on a single phase 240v circuit?

 

[Papa Charlie]

I spent some time with a sales rep for a dealer today asking some questions. First off - I was correct about Fusheng Industrial taking over FS Curtis. It appears, from what the sales rep I spoke to said, that FS Curtis still does assembly in the US, but their motors and compressors are largely manufactured over-seas from existing designs. He did state that Champion was more likely to be mostly US-made where some of their motors may come out of Mexico or Brazil, as opposed to Asia.

On the subject of electrical requirements - his charts showed that a 5hp motor compressor is recommended to be on a 60a breaker and a 7.5hp motor is recommended to be on an 80a breaker. He also said that inrush, or starting, current could approach 2x full load amps.

There is going to be some headroom in the recommendations, for sure, but that is still high enough I am not sure I can get a compressor in the size range I am wanting to run on my circuit. I know from my load testing with my welder that the breaker will hold on in to the 40a range. As to how long it does is dependent on how high the draw is. Where at 43-45a the trip is pretty fast. If inrush/starting current on a compressor is under that with a running amperage closer to 30a then I may be able to squeeze by. Going off of the chart data that was provided, though, even a 5hp unit might be a tall order.

Going the other way - the chart data did point to a 3hp unit being capable to run on a 30a circuit. I don't think that is going to net me much more than I already have with my 20gal compressor. The motor on it is labeled as a 5hp motor, but it is a 110v unit that will run on a 15a circuit (I've done it, but a 30a runs it a lot better - no idea what the running amperage or inrush amperage is, I will have to load test and find out). So I don't think the motor is actually a 5hp.

Does anyone have any info on what size breakers they are running what size compressor motors - in the 3-7.5hp range on a single phase 240v circuit?

What voltage are you looking at? Must be a 110V circuit to pull 60amps on a 5HP motor.

 

[FlyFishn]

What voltage are you looking at? Must be a 110V circuit to pull 60amps on a 5HP motor.

240v single phase.

Part of what was said was that inrush/starting current can be 2x FLA (full load amps). Some 5hp units were in the ~30a range FLA rating, so I think that is where the 60a breaker recommendation was - the 60a being 2x the 30a of the FLA.

That is why I am asking if people can list there compressor hp and circuitry ratings to compare.

 

[pontiac428]

If I had a 5 hp motor that blew a 40A breaker on inrush, I would return it to the dealer as defective. If they call for a 60a circuit, ask if they will cover the fire insurance on your house, because you're well on your way to needing it. That's some beer-battered bull$h!t right there.

 

[FlyFishn]

I am looking at some 5hp units here that have a 23 amp FLA rating. So by the same "numbers" - doubling the FLA is 46 amps. I am not all up on common breaker sizes for buildings, but I know there are 45 and 50a breakers for generators. It would seem, to me at least, the next common size breaker from 40 would be 50 - not 60. And 46 is technically higher than 45, so I could see there being an issue with anyone "recommending" a breaker 1a under that. I am not sure where the 60a recommendation comes from, other than that is the "headroom" (the gap from 46a from doubling the FLA to the 60a recommended breaker size) that I was referring to earlier as likely being there. There is probably a lawyer somewhere on top of what that recommendation is.

If I had a 5 hp motor that blew a 40A breaker on inrush, I would return it to the dealer as defective. If they call for a 60a circuit, ask if they will cover the fire insurance on your house, because you're well on your way to needing it. That's some beer-battered bull$h!t right there.

As to the 5hp compressor motor not tripping a 40a breaker - I'd like to see if anyone can verify that from a real-world use-case.

If a 40a breaker doesn't trip on a 5hp compressor then I would be content at that HP enough to get one and give it a try. Likewise, possibly a 7.5hp (if the same theory - not tripping a 40a) but I think in this point of my research that is asking an awful lot = I'd likely be a lot closer to disappointment there than at 5hp.

 

[pontiac428]

Why should it be asking a lot? I have been running my 5hp compressor for years on a 30A breaker, and the math shows that it not only covers it, it has room to spare. I know, I know that different motors have different inrush characteristics. But double? No way, Jose.

 

[mksj]

So a couple of factors to consider, and part of this is based on both the motor specs and the breaker specifications, in addition if it is a 2 stage vs. single stage compressor (i.e. load is higher with 2 stage). First if you have a 30A circuit/wiring, you can not pull a full 30A from the circuit, there is always a degree of derating otherwise the wires will overheat if run at full load. A motor has a rated running amps (FLA), and also a service factor, so it is able to draw at its maximum rating the FLA x SFA for short periods. On my Champion 5 Hp two stage compressor at 230VAC the FLA = 21 and the SFA = 24A, so technically it could run on a 30A breaker and the typical over-sizing of the breaker allowed for motors is FLA x 125%. 26.25A and you round up. My motor is a higher efficiency rating then typical single phase motors, so something like 23A is more common. There is some up-sizing of the breaker for motor loads, but there are also different breakers with different trip curves which allow for higher starting motor loads.

My compressor manual recommends a #8(6) wire for 5 Hp and #6(4) for for 7.5Hp, and drop a size () or longer runs. So it also gets a bit murkier as to the amapacity of the wires and also the ratings of the terminals. Typical ratings for #8 wire is 40A, #6 55A for Romex, higher for THW types. I have my compressor on a 50A circuit breaker, and I run #6 wire to the socket and then use a 50A extension cord which is hard wired to my compressor. Previously I had the same compressor hardwired to sub-panel with pulled #8 THHN through flex conduit. You could get by running a 5 Hp compressor off of a 40A breaker, but I use a 50A breaker and wiring to give some margin and use it for other equipment. A 60A breaker is a bit excessive. I also often use 50A breaker and wiring for 5Hp lathes , a 60A for a 7.5 Hp unless unusually high loads. See attached chart.

When you get down to ordering a compressor, make sure you know what you are ordering, often the pictures and advertise specs. do not match the model number. So like with the Champion RV series they have lesser 5 Hp models without mag starter that have 3600 RPM motors, the mag starter versions are 1800 RPM. Also things like an after-cooler, automatic drain, etc. if purchased separately are much more expensive. Get all the details, some have packaged deals with isolation feet hoses and other accessories, but get everything in writing/email first. Also some drop ship from the manufacturer at no additional cost, others with lower pricing charge.

Last, but not least, the price difference between a 5 Hp model and a 7.5 Hp is often something like $100, most share everything else, so you are only paying for a motor upgrade (most cases). There are some high flow V4 compressors in the 7.5Hp range, but generally you see those in the 10Hp and higher. So if you are going do any high CFM work, it pays to get a 7.5Hp, otherwise the 5 Hp is the sweet spot. The pumps will run a bit slower, so quieter, but most of the noise is from the air intake. I eventually plan to pipe mine into a sound deadened box with a car air cleaner.

I would read this thread on what breaker sized worked for a compressor 7.5 Hp motor, so you can get by possibly with smaller breakers but I would give yourself a minimum of a 125% margin an wiring and breaker size:

220V, 1-Phase, SF 36 AMP Motor Trips Circuit Breaker

Happy Veteran's Day everyone! I have a 7.5HP air compressor you've helped me with before. It recently began tripping the circuit breaker upon a cycle start - 135 psi I believe. If I let the air out of tank, it worked fine on initial fill cycle, but upon refill, the breaker tripped every time...

www.hobby-machinist.com