Magnetic starter switch for 4hp compressor

[strength_and_power]

The sticker on a new to me compressor says a mag starter switch is necessary. I turned to Amazon and there is quite a variety and price range and the reviews are all over the place. Can anyone recommend a decent one that won’t break the bank? Compressor will see very occasional use, probably once a month to blow off the mower and maybe air up some tires.

Thanks I’m advance

 

[wyliesdiesels]

are you sure the motor label says 4HP? thats a non standard size. post a pic of the motor nameplate

 

[walta]

The sticker on a new to me compressor says a mag starter switch is necessary. I turned to Amazon and there is quite a variety and price range and the reviews are all over the place. Can anyone recommend a decent one that won’t break the bank? Compressor will see very occasional use, probably once a month to blow off the mower and maybe air up some tires.

Thanks I’m advance

Seems unusual for a compressor that requires a starter to not come with a factory installed starter.

Do you have a link to the compressor?

Walta

 

[mm08822]

Another option if the motor has internal overload protection, is to just use a 5 hp rated pressure switch that has an on-off lever. It also needs to include the unloader valve.

 

[strength_and_power]

This is what I have on my phone, I’ll look at the motor when I get home to see if it has additional info

 

[mm08822]

Not sure if the labelling is correct. It states no overload protection present for motor and requires a starter for that purpose.

However, the red button on the motor end bell sure looks like a resettable thermal overload.

 

[wyliesdiesels]

This is what I have on my phone, I’ll look at the motor when I get home to see if it has additional info

that label is completely useless and doesnt match the motor that is on the compressor since the motor has integral OL protection (red button on end)...

 

[walta]

I missed that we are talking about a used compressor.

Have you see the compressor run and cycle on and off a few times?

Being a used machine, in my mind everything about the unit is suspect and likely wrong until proven otherwise.

The first thing is will this machine kill me? Has anyone tried to repair this tank? Craw around the bottom of the tank and look for non-factory welds or screws in the tank. This would indicate the tank must be replaced as proper repairs simply cost more than this compressor is worth and an improper repair is likely to fail in a way that could kill me.

The list of things you need to check is very long.

What is the min and max speed in RPMs this pump is rated for?

Does the current motor with the current pullies spin the motor at the correct speed?

Is the current motor large enough to spin this pump at this speed?

Is the current pressure switch rated to operate the motor you have?

Is there a over pressure relief valve to vent the tank should the pressure switch fail to turn off the motor?

Is every electrical part on this machine grounded?

Understand the amount of stored energy 80 gallons of 175 PSI air is enormous if the tank should fail and release that energy in a second it would be a disaster.

The starter label on the motor indicates to me the motor was replaces at some point. Having a motor starter on a compressor would be nice but at 4 HP not absolutely necessary. Assuming the switch is rated for this motor.

I do not feel safe around air tanks unless I know they have been hydro tested in the last few years.

Walta

 

[u2slow]

I've been using one of these on my 3hp/10cfm machine for a couple years

https://www.princessauto.com/en/pressure-switches/product/PA1000000900

 

[strength_and_power]

I missed that we are talking about a used compressor.

Have you see the compressor run and cycle on and off a few times?

Being a used machine, in my mind everything about the unit is suspect and likely wrong until proven otherwise.

The first thing is will this machine kill me? Has anyone tried to repair this tank? Craw around the bottom of the tank and look for non-factory welds or screws in the tank. This would indicate the tank must be replaced as proper repairs simply cost more than this compressor is worth and an improper repair is likely to fail in a way that could kill me.

The list of things you need to check is very long.

What is the min and max speed in RPMs this pump is rated for?

Does the current motor with the current pullies spin the motor at the correct speed?

Is the current motor large enough to spin this pump at this speed?

Is the current pressure switch rated to operate the motor you have?

Is there a over pressure relief valve to vent the tank should the pressure switch fail to turn off the motor?

Is every electrical part on this machine grounded?

Understand the amount of stored energy 80 gallons of 175 PSI air is enormous if the tank should fail and release that energy in a second it would be a disaster.

The starter label on the motor indicates to me the motor was replaces at some point. Having a motor starter on a compressor would be nice but at 4 HP not absolutely necessary. Assuming the switch is rated for this motor.

I do not feel safe around air tanks unless I know they have been hydro tested in the last few years.

Walta

The backstory on the compressor is this, in our previous building, we had 2 separate work areas, each having its own compressor. This was on the prep side and ran a small burr grinder and an impact, not used daily but a few times a week. We changed buildings and the new layout allowed one compressor to feed both our prep and paint areas. The other compressor got tucked away and my boss came across it one day and asked me if I had a compressor for my shop and if not, take this one home because we need the space. That being said, I have seen it run and am comfortable with it in my shop.

 

[strength_and_power]

that label is completely useless and doesnt match the motor that is on the compressor since the motor has integral OL protection (red button on end)...

Thanks for stopping back by. Here is a picture of the plate on the motor itself

 

[wyliesdiesels]

SPL rated motor.... 16.5HP is around 3hp and the motor states it has OL protection so....

 

[gungatim]

The backstory on the compressor is this, in our previous building, we had 2 separate work areas, each having its own compressor. This was on the prep side and ran a small burr grinder and an impact, not used daily but a few times a week. We changed buildings and the new layout allowed one compressor to feed both our prep and paint areas. The other compressor got tucked away and my boss came across it one day and asked me if I had a compressor for my shop and if not, take this one home because we need the space. That being said, I have seen it run and am comfortable with it in my shop.

Allow me to say, You ****!

That's a helluva compressor for blowing off the mower and airing up tires.

 

[PCustoms]

SPL rated motor.... 16.5A is around 3hp and the motor states it has OL protection so....

FIFY

 

[OccupantRJ]

Hard to beat that deal!
I have had a workshop for 60 years with all kinds of air tools, along with two blast cabinets, and after getting that unit up and running the first thing I would do is set the cutoff pressure to about 120 psi. For what you are doing there is no need to work the compressor any harder than that. Power consumption, noise, heat, wear and tear all come into play. No need to use a baseball bat to kill a fly. You will need to keep water bled from the tank regularly.
Good going!

 

[walta]

You ****

Sounds like a great deal.

Drain the tank and run it as is.

Walta

 

[strength_and_power]

SPL rated motor.... 16.5HP is around 3hp and the motor states it has OL protection so....

So, is a magnetic starter required? I’m assuming the label on the motor is more accurate than the tank label but aside from a basic understanding of the label, I’m lost. My goal is to learn so I’m not asking the same question a few years down the road and not create a fire/shock hazard.
Thanks in advance
Scott

 

[strength_and_power]

Allow me to say, You ****!

That's a helluva compressor for blowing off the mower and airing up tires.

I’ve been with the company for 24 years through great times and some downright crappy times. My boss is from up or down the bayou in LA and believes in lagniappe, this time being in the form of a compressor. I won’t be sad if I never have to update my resume.

 

[walta]

Seems to me the compressor was repaired and the motor was replaced by a professional maintenance crew that knows what they were doing with the budget to do the job right and orders avoid costly down time. If that sound correct, I would not be concerned by the label on the motor.

The worst case is the contact in a under rated pressure switch stick and the over pressure valve begins venting. If it would make you feel better add a second over pressure valve for $10. The mag starter would likely cost $300.

https://www.amazon.com/Compressor-Safety-Relief-Pressure-Valve/dp/B07JHHDWGB/?tag=atomicindus08-20

Walta

 

[sparky 1971]

So, is a magnetic starter required? I’m assuming the label on the motor is more accurate than the tank label but aside from a basic understanding of the label, I’m lost. My goal is to learn so I’m not asking the same question a few years down the road and not create a fire/shock hazard.
Thanks in advance
Scott

No, if you have the pressure switch there, just put a 250 volt 20 amp cord on it and plug it in.