Air Compressor: What would twin-cylinder mean?

[rollingstein]

Air Compressor: What would "twin-cylinder" mean?

I'm figuring out details about an old compressor and it's made by a Greek Company. I can't find too many details but one part that confuses me is it says "twin cylinder".

Picture below. Specs say:


Oil lubricated twin-cylinder, three-phase compressor belt Air receiver: 1000 Lt Power: 7.5 HP 7.5 Suction: 1900 lit / min Pressure: 12 bar Voltage: 400 Volt Dimensions: 2330 x 800 x 1460 mm Certification: CE & TUV Hellas Warranty: 12 months



It doesn't look like a twin stage unit. What's the function of two independent compressor units on one tank? Redundancy? Or they run them in parallel? Can anyone comment from the photo?

Would the tank be one large 1000 L or a split one? Wondering if anyone has seen similar units.

 

[Danger]

I've never seen anything quite like that. Usually, a twin has both cylinders together the same as in a motorcycle engine. Maybe the thing is segmented in the middle as you suggested; there appears to be a tap on each end. That would also explain why there are two drive motors. On the other hand, the use of a single pressure gauge argues against that.

 

[jim hardy]

Can't tell from end view whether the compressors are single or two cylinder -
that description sounds like it's describing individual two cylinder compressors.

If it's two stage, one cylinder will be smaller than the other.
175 psi sounds like two stage...

No reason they couldn't put two similar compressors on one tank to increase volume.
Clearly they both pump into same tank for there's only one pressure switch.
Do the motor nameplates say 7.5 hp or is that their total ?



http://www.ch-commercial.com/products-detail/products-series~air-compressor-pumps/tf2111-air-compressor-pumps-two-stage-model/

 

[rollingstein]

Do the motor nameplates say 7.5 hp or is that their total ?


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Yes, it says 7.5 + 7.5. (sorry, not very clear in the photo.)

 

[rollingstein]

there appears to be a tap on each end. That would also explain why there are two drive motors. On the other hand, the use of a single pressure gauge argues against that.

Maybe that one on the rights the tap and the other one's merely a safety valve.

 

[jim hardy]

Yes, it says 7.5 + 7.5. (sorry, not very clear in the photo.)

you're right - it's Greek to me.
http://www.airblock.gr/aerosympiestes-kompreser/emvoloforoi-toros/ilektrokinitoi-toros/aerosympiestis-1000-7-5-7-5-toros.html

Δίδυμος ελαιολίπαντος δικύλινδρος, τριφασικός αεροσυμπιεστής με ιμάντα

Αεροφυλάκιο : 1000 Lt
Ισχύς : 7,5+7,5 ΗΡ
Αναρρόφηση : 1900 lit/min
Πίεση : 12 bar
Τάση : 400 Volt
Διαστάσεις : 2330 x 800 x 1460 mm
Πιστοποίηση : CE & TUV Hellas
Εγγύηση : 12 μήνες

Single stage compressors don't do well above ~ 90 psi.
Of course marketeers will claim the absolute maximum it can produce at zero flow.
So if you're contemplating purchase, and you really do need 150 pound air, verify those compressors are actually two stage.

http://www.brighthubengineering.com/hvac/63725-effects-of-a-multi-stage-air-compressor/


http://www.brighthubengineering.com/hvac/63715-operation-of-an-air-compressor/
http://www.brighthubengineering.com/hvac/63720-the-operation-of-air-compressors-part-two/