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  #31  
Old 11-01-2008, 12:22 PM
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Getatorch & I were talking about those switches the other day. He noticed that Grainger was showing them to come in 2 amperage ratings that differed about 20 bucks in price.

If your's was the lower one then it's probably surprising it last this long.
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  #32  
Old 11-01-2008, 01:11 PM
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Hey I just went over to grainger to check out what they have. After looking at the first of eleven pages I have to say I'm at a loss as to which is what I need for replacement.

There is label on the old Switch shown in the picture. Any Idea what I need? Here is the first page at Grainger
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  #33  
Old 11-01-2008, 02:43 PM
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Tommy, go the Tractor Supply they have a Campbell Hausfeld for about $41.00 and cuts in a 95 psi and out at 125 psi. Just like your photo. And is for 240v with three outlet ports along with plugs for those you don't need. No need to pay the high price of Grainger.

Here's the link: http://www.tractorsupply.com/webapp/...g=true&cFlag=1
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  #34  
Old 11-01-2008, 02:48 PM
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Quote:
Originally Posted by TommyA View Post
Hey I just went over to grainger to check out what they have. After looking at the first of eleven pages I have to say I'm at a loss as to which is what I need for replacement.
What size pipe does it screw onto ? male or female ?
Does it have an unloader ?
Is it also used as a ON OFF switch for the compressor ?

Do you want an adjustment for differential pressure.
95 on - 125 off is 30 psi differential.
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  #35  
Old 11-01-2008, 02:50 PM
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Well Tommy, your old switch shows to have the unloader valve & an on/off lever so it seems like you'd probably want the same configuration. And your motor claims to be 6 hp which it ain't but let's say it's a 5hp & the label on the tank indicates 15 amps @ 240volts. Then you need to look at the pipe fitting just because it would be a little less trouble to use what you already have.

So you need a 15 amp minimum 240volt (2 pole) with unloader and switch lever to cut in at 90psi/off 120psi and with the correct male or female threads.

The trick seems to be getting all the whistles & bells on one unit, like I don't see the same pressure/amp ratings with the lever on the Grainger page. May be there but I didn't see it.

Do you use that lever for your on/off switch? I think that's more common on smaller hp/amp switches.

It might be easier to just find a Furnas dealer in your area & take them your old switch.

Or maybe Grumpy's suggestion would be better. Just be danged sure you get one that has the unloader or you got more rigging to do later.
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  #36  
Old 11-01-2008, 03:28 PM
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I believe the one Grumpy shows would work the best as the unloader valve on the older switch is plumbed for the top. The square D switches would require me to make a new connection.

I defiantly need to do something soon. Today I started to work on several projects that I planned to work this weekend but without air I wasn't able to do anything. I have a lot of air tools from working in the aviation industry.
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  #37  
Old 11-01-2008, 03:58 PM
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May be this one.

Looks like 3 HP. may not last as long as your old one.

http://cgi.ebay.com/NEW-Furnas-HD-Ai...QQcmdZViewItem
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  #38  
Old 11-01-2008, 05:07 PM
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Gwiz I just looked at the one you suggested and am I wrong that it also states 3HP? It looks as heavy as the one I have so I'm not concerned that it would not hold up as well.

Looking at the label on the motor it shows that max output is 6 hp so who knows exactly what the real value is. I believe that Boilerman came out with what the motor is actually displacing. To be honest if I can find a switch that I can install and last as long as this one did I would be happy.
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  #39  
Old 11-01-2008, 06:22 PM
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I looked on ebay too; most of them were either for 1 hp, like on the Grainger page or they were preset for 175lb shutoff or they had no unloader, etc.
Of course, you could always reset the cutoff/kick-in if you can find the 5hp with an unloader & lever switch.

God knows how old the switch on my compressor is but it's always been used to trigger a contactor & doesn't carry any current to speak of. It was set for 175 psi when I got it but I tuned it down to 100/140 just because I don't need 175 so why waste the power to pump it up?
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  #40  
Old 11-01-2008, 06:58 PM
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On my compressor I had a 3 hp motor and was using a pressure sw. like you have there to start and stop the compressor and I had been leaving the compressor on 24/7.

One night I was awoken at around 2 am with this god affule noise coming from the building that I had the compressor in.

Got out there and found the compressor running and the relief valve lifting. Shut off the motor and next morning I took the pressure sw apart and found the sw contacts had welded closed and the darn thing could not shut off.

I changed the system to use a pressure sw to close a contactor( mag.Sw) and the pressure sw just carries the contactor closing coil current.
Since I changed to this set up I have not had any problems with burnt up contacts.

In the above instance, if the relief valve had not worked I may still be looking for my compressor.
I now turn off the compressor at the end of the day.
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