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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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14th Jul 2018, 2:05 pm | #21 |
Rest in Peace
Join Date: Apr 2008
Location: London, UK.
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Re: Single Phase AC Compressor Motor
The safety valve is supposed to be a backstop in case the pressure switch fails to open. Relying solely on the valve to prevent the receiver exceeding its rated pressure keeps the valve free but may not comply with applicable regulations and good practice. If the control gear has been removed, the overload protection for the motor has probably gone with it*, which is mandatory for motors over 0.37kW output (1/2hp). Given that the air receiver is 40 years old, unless it has a recent pressure test certifiate that may also be questionable. If the motor does turn out to be toasted, the most economic course of action here may be to cut losses and replace the complete unit.
* A thermal overload relay matched to the motor is sometimes built into an all-in-one pressure switch / unloader valve, or it is in the starter if separate. |
15th Jul 2018, 4:18 pm | #22 |
Octode
Join Date: Nov 2005
Location: Ayrshire, UK.
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Re: Single Phase AC Compressor Motor
Hi Lucien
The receiver gets tested annually for insurance purposes and is apparently quite sound. Alex reckons that there are pressure relief valves fitted to the heads of the two cylinders of the compressor. The compressor seemingly passes its annual inspection so I guess it must be reasonably OK. I'm not going to get too deeply involved. If I can get the motor running I'll return it and Alex can refit it. On the other hand if it's toast then I'll let him know and he can decide whether to get a new one, get a new compressor or just carry on as he is already. Oddly enough, a customer came in the other day and recognised the compressor as an Ingersoll Rand unit. He used to work for them and reckons that spares are probably still available for it. However, Alex is going to retire before too long as he's getting on a bit now. He's been 'in the trade' variously for about fifty years and he's really had enough by this time. I'll miss him when he does finally retire; he's been a good old friend. I've bagsied the compressor when he does go as I fancy rebuilding the pump part of the compressor and fitting a small diesel stationary engine to power it. Tim
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15th Jul 2018, 5:04 pm | #23 |
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Re: Single Phase AC Compressor Motor
An Ingersoll-Rand V-2 pump means a better compressor than anyone is likely to buy nowadays.
Even if you did add a small stationary engine.... especially if you added a small engine, you'd need a 'genie' unloader valve to take the load off the engine when the receiver was up to pressure. Letting the safety blow off would leave your engine running at max power doing nothing but waste fuel and make fumes. It needs a proper pressure switch and an unloader to give things an easy life. If your engine stopped, you'd have to dump all the air out of the tank before you could start it! David
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15th Jul 2018, 9:58 pm | #24 |
Octode
Join Date: Nov 2005
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Re: Single Phase AC Compressor Motor
Once again David...totally agree with all you say. Lister made a diesel powered compressor and I'll base mine on what they did but with the V2 Ingersoll Rand pump and the 200L receiver. I'd ideally like the electric start Lister but they're pretty rare and attract a premium price so probably not on for this project. I should be able to run my air cut-off tool or my air powered drill continuously without having to stop and wait for the compressor to 'catch up' as happens with my current single cylinder, single phase 50L Aldi compressor.
Tim
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