Compressor question

[Dave Winters]

So , my new shop has half the space heated and half unheated. I need to locate my stationary compressor in the unheated area. Short of building a "shed" for it, I'm looking for ideas to heat the motor in the winter. Maybe a block heater of some sort? Should I use a lower viscosity oil? Thanks as always!

[Mike Henderson]

Assuming you have a standard induction motor, it probably wouldn't need to be heated. Check the specs on the motor but most electric motors can safely operate at pretty low ambient temperature. I think most are spec'ed to -20C or even -30C. How cold does it get there?

The problem is not the motor itself but the grease in the bearings. Ignoring the grease, the motor will operate at extremely low temperature (say -100C).

Now, the pump may be another question. I assume you have oil in it and you should spec the oil to the temperature you expect.

Mike

[David Kumm]

I agree with Mike that the pump is the issue. Is it cast iron or AL? Pressure lubed or splash lubed? Does it run fast or slow? A cast iron 700 rpm pump will handle cold better than a splash lubed aluminum 1200 rpm pump. Pressure lubed will handle any weather but they are fairly rare until you get into the higher end compressors. Dave

[Tim Einwalter]

My reciprocal oil filled compressors will start reliably until it gets below 20. Pretty much guaranteed they won't start by 10 degrees. Usually, I put a map torch on the bottom of the compressor casting and hold it there for 5 minutes to warm the oil. Once it starts, it's good for the rest of the day.

Note that the drains will freeze solid in cold weather.

[Doug Garson]

Since you are building a shed for it, why not insulate the shed and add a thermostatically controlled baseboard heater? Solves the starting problem and also prevents freezing in the drains.

[Jon McElwain]

When I lived in Alaska, we kept freezers in an unheated shed. In the winter, I put one of those clamp work lights with a 40 watt bulb under the freezers to keep the motor from getting too cold. Sometimes when it got exceptionally cold I would do 60 watts. Freezers lasted decades. Might work with the compressors.

[Dave Winters]

Thanks, guys. It's a big Saylor Beall two stage 5hp cast iron pump. Not sure if it's splash or pressure lubed. Here's the manual..


http://www.saylor-beall.com/wp-content/uploads/700SeriesManual.pdf

[Dave Winters]

Wonder if something like this would work:
https://www.amazon.com/Kats-1160-300...c+block+heater

[David Kumm]

Saylor Beall makes great compressors. Generally splish lubricated unless PL on the model number. I would only be worried in extreme cold and if needed then, put a little ceramic heater on the compressor to warm up the pump and motor for 5 minutes. The heat from the compressor will warm the space a little. I have a furnace in half my shop but a hot dog type portable electric heater will take the chill out. Dave

[Bruce Wrenn]

Synthetic oil performs better both in hot and cold. Change the oil to synthetic.

[Bill Orbine]

There's a chart in manual for oil viscosity to use for different ranges of temperature between 0-120 degrees. Otherwise call the factory for recommendations.

[Mike Cutler]

Dave
What is the purpose of this compressor?
You would be better off having located in the heated, more climate controlled, area.

You can heat the compressor itself, but that receiver tank is going to be working very hard with the that large differential temperature across it. You need a significant moisture removal strategy for cold weather. You're going to get a lot of moisture in that receiver tank.
If it has to be in the non heated area, you really should enclose it, and insulate it. You would be stunned at how warm a 100watt light bulb, or a poultry lamp, could keep the entire compressor and enclosure warm. Put a manual air intake vent on the enclosure.

My compressor sits in the open, unheated, non climate controlled garage all year. Temp range -5 to 100degF. throughout the year. If I need to use it in the winter I have a 1000watt dual halogen light stand that can warm it back it up.

[Scott T Smith]

I would use a synthetic compressor oil and put a thermostatically operated heat lamp pointed at the compressor crankcase.

I’ve used the magnetic oil pan heaters, but I think that the heat lamp would require less energy and be just as effective.

[Ronald Blue]

Synthetic compressor oil is the way to go. It will have an ISO rating rather than a typical viscosity rating. ISO 32 (10 weight) will cover your temperature ranges. Hydraulic oil is rated that way as well. Look for an R & O type. That's rust and oxidation. For your cast iron compressor that's a good choice. If there is no oil filter it's not likely a pressure lube system. All the pressure lube systems I have been involved with have filters.