Older Fliteway compressor. Just a little guy.

[Danguitarman]

I think I got a fair deal on this older compressor. 65 bucks on Craigslist. It runs great, super quiet, and it's in good condition, too. Was owned by a guy in his 70’s that was obviously a gearhead and knew how to take care of his equipment. Now, I'm not expecting this thing to set the world on fire, (it's only a 1/2hp motor) but it shuts off at 80psi. Does this seem normal for a little compressor like this? No, I'm not trying to run a die grinder with it, just fill tires and blow things off. Curious about what you guys think. Thanks. Dan.

 

[reptilezs]

pressure switch might be adjustable

 

[The Cobbler]

have you confirmed the gauge is accurate? it could be off
does the tank have a working pressure rating?
the higher the pressure the more HP you need ( the more load ont he unit) I would be careful on an older compressor to boost the pressure

 

[Danguitarman]

pressure switch might be adjustable

I had considered looking into that.

 

[Danguitarman]

have you confirmed the gauge is accurate? it could be off
does the tank have a working pressure rating?
the higher the pressure the more HP you need ( the more load ont he unit) I would be careful on an older compressor to boost the pressure

To be fair, I have not checked the accuracy of the gauge. I did look around the tank itself for some sort of working pressure rating. I know they will sometimes be stamped around the fittings, but I cannot find any. Really, with such a small pump and motor, it would not surprise me if this compressor was meant to run around 80-90 psi, but I'm no compressor guru.

I know a lot of guys on here know a ton about compressors, and since I cannot find anything relating to this particular unit online, I figured I'd pick everyone's brains just for the hell of it. Thanks for the input

 

[larry_g]

have you confirmed the gauge is accurate? it could be off
does the tank have a working pressure rating?
the higher the pressure the more HP you need ( the more load ont he unit) I would be careful on an older compressor to boost the pressure

Pressure is independent of HP. HP determines how fast the compressor can turn and the rate it can reach a rated pressure. Lower the HP and it will take longer to reach the set pressure due to having to run the pump slower to stay within the motor ratings.

That said most single stage compressor heads will do 120psi without a problem. What you can do is turn up the pressure cutout point and then monitor the motor current to determine if the motor can run the pump at that pressure/speed.

lg
no neat sig line

 

[The Cobbler]

Pressure is independent of HP. ...
lg
no neat sig line

you're saying HP is independent of HP, yet you go on to say if the speed is adjusted to compensate, it will turn it. that means that it is dependant on HP

. a given HP that can build 10 PSI is not capable of building 120 psi at the same RPM.

 

[redmondjp]

Pressure is most certainly not independent of horsepower! It takes more power to pump up to a higher pressure, with all other factors being equal. Don't believe me? Hang a clamp-on AC ammeter on your motor leads and watch the current increase along with the pressure.

With all that being said, I don't see 80psi being an unusual shutoff pressure for a unit of this size. Our family has had a number of older 1-2HP Craftsman air compressors from the 1960s and 1970s and they had a similar shutoff point from the factory - around 80 to 85psi IIRC.

 

[larry_g]

you're saying HP is independent of HP, yet you go on to say if the speed is adjusted to compensate, it will turn it. that means that it is dependant on HP

. a given HP that can build 10 PSI is not capable of building 120 psi at the same RPM.

Pressure is most certainly not independent of horsepower! It takes more power to pump up to a higher pressure, with all other factors being equal. Don't believe me? Hang a clamp-on AC ammeter on your motor leads and watch the current increase along with the pressure.

With all that being said, I don't see 80psi being an unusual shutoff pressure for a unit of this size. Our family has had a number of older 1-2HP Craftsman air compressors from the 1960s and 1970s and they had a similar shutoff point from the factory - around 80 to 85psi IIRC.

I do believe that you 2 are confusing pressure with volume. Pressure can come in many different HP compressors. Volume at pressure (CFM@PRESSURE} is very dependent on HP.

lg
no neat sig line

 

[The Cobbler]

take ops compressor, it pumps to 80 psi , the cfm or volume we don't care about right now.
will that same motor with the same pulley configuration and pump build to 500 psi ? (saftey etc aside)
no it wont ... you need more HP .
PSI is dependent on HP .

 

[larry_g]

take ops compressor, it pumps to 80 psi , the cfm or volume we don't care about right now.
will that same motor with the same pulley configuration and pump build to 500 psi ? (saftey etc aside)
no it wont ... you need more HP .
PSI is dependent on HP .

You can put unlimited HP on that pump and never reach 500psi.

l;g
no neat sig line

 

[The Cobbler]

of course I know that. .. but that's not the question, you imply is HP doesn't matter.
I suggest it does.

 

[Danguitarman]

That said most single stage compressor heads will do 120psi without a problem. What you can do is turn up the pressure cutout point and then monitor the motor current to determine if the motor can run the pump at that pressure/speed.

I think I'll check out the cutoff and see how the little guy fairs with incrementally higher psi. Thanks for the suggestion.

 

[Danguitarman]

I don't see 80psi being an unusual shutoff pressure for a unit of this size. Our family has had a number of older 1-2HP Craftsman air compressors from the 1960s and 1970s and they had a similar shutoff point from the factory - around 80 to 85psi IIRC.

I appreciate the info. I cannot find anything on this compressor, so to know that you've had others with a similar pressure cutoff level is good to know.