Oil Separator

[sdumper]

I have a 19.1 CC Rotary that is getting so hot that water boils when sprayed onto the shell. The compressor says its thermally protected and its not shutting off but water boils at my elevation at roughly 100c.


I can add a fan blowing directly on it but I am concerned this may be a symptom of a bigger problem. The direction I am leaning is a failure in the oil separator where the oil is not being returned quickly enough. Now I have spare oil separators and I fully plan to swap out the oil Separator and possibly the compressor tomorrow but before I do that I want to make sure this isnt normal for a 19.1cc matsush1ta compressor under the brand Panasonic...

Note max operating conditions:
Condensing Temp. 149°F 65°C
Return Gas Temp. 95°F 35°C
Discharge Gas Temp. 239°F 115°C
Motor Wire Temp. 266°F 130°C


link:

http://www.panasonic.com/industrial/...s3r126b-1a.pdf

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[eligray]

that is too hot.

I'm not a phase guru by any means, but drewmeister and boshuter have told me a couple times to keep a rotary under 80c. If water boils on it, it's over 100c.

I've also had temp problems with the compressor on my propane-chiller, but so far the only real advice I've recieved is from Gary: with PC-desirable suction pressures, it WILL overheat.

[bartx]

For me it isn't much too hot. Just provide some airflow on compressor and you'll see 10-20C temp drop.

[sdumper]

Originally Posted by bartx

For me it isn't much too hot. Just provide some airflow on compressor and you'll see 10-20C temp drop.

Let me try that and see what I get...im also running a low charge and im not frosting up my accum yet. I just dont want to burn up the compressor from lack of oil return and because it was so hot I started getting concerned that it wasnt receiving oil back from the separator.

I suppose though if it wasnt getting oil back then that oil would be flowing into my evap and freezing it up once it dips into the -100c and colder range.

[n00b 0f l337]

The appearence of boiling can appear around 80C. use a thermocouple, get us a good temperature.
Second, we need some more info.
Pressures, discharge temperature, airflow, the works.

[sdumper]

Pressure 150 psi
Ambient 60f
Air flow direct fan blowing on it
Actual temp after 1 hour ... i will post back but I have a strong feeling its not getting adequate oil. Although I have another Matsuh1ta rotary (smaller one a 16cc ) that also gets hot as heck.

[Ozzfest05]

Alot of rotaries run hot it may be normal that this compressor is hotter then what your used to, maybe add a fan or two, could you not try and bring the frost line back to the compressor for added cooling I imagine this is first stage? I would try bringing the frost line back to the compressor and seeing if it will still hold the first stage load this way when unit is idling it will run cool under load it will still get hot but atleast you wont burn the compressor within first few months.

[sdumper]

Originally Posted by Ozzfest05

Alot of rotaries run hot it may be normal that this compressor is hotter then what your used to, maybe add a fan or two, could you not try and bring the frost line back to the compressor for added cooling I imagine this is first stage? I would try bringing the frost line back to the compressor and seeing if it will still hold the first stage load this way when unit is idling it will run cool under load it will still get hot but atleast you wont burn the compressor within first few months.

This is actually the second stage. The first stage is cool enough to put my hand on it...but he first stage is directly in front of the radiator fan and its heavilly charged for load so its frosted completely....

Im home today so im going to try some different things and worse case scenario ill replace the oil circuit and compressor...

I just moved my expansion out of the way of airflow and attached a thermocouple bead directly to the shell so as soon as I reach my starting point ill see how hot it gets after an hour of no load....

[sdumper]

Hmmm....

I may have gotten lucky because I was all set to do some chopping and replacing of components

Charged at running 150 psi shell temp went to 90c may have gotten warmer but this is no load.
Charged to running 170 psi and accumulator frosted all the way I was at 86c to 87c.
Small room fan blowing directly on the compressor temps dropped to 58 to 60c and appear to be holding....hmmmm I cant exactly ship with an external fan so im going to need to get more creative.

[n00b 0f l337]

Time to get creative.
You have a metal cart, can bolt an L angle down and pickup a 110VAC fan and of course fan gaurd.
But again, this is why air flow is important.
The refrigerant inside is best above vacuum because then you have good transfer of heat to the shell where it can be cooled.

[sdumper]

Yepper I have a fan already prepped and wired I just need to change the color because its white and that doesnt match ... lol :-)

[runmc]

Is this the cascade with the big blue oil sep ? Did you add oil for the oil separator?

[sdumper]

No this is yet another build using a Henry 5180 short stature Helical Oil Separator.

The oil sep and compressor are fine. Once I mounted a small fan blowing directly onto the shell my temps dropped from 90c to 50 to 58c in fact my temps never rise above 58c now even under 300 watts of load.

As a side note I was ready to hang this one up and replace the oil sep but after chatting with NOL he pointed me to try a Fan and it was all it needed. Thanks Adam good tip.

[n00b 0f l337]

Hey thats the way to go, it might seem like a bad idea, but a good heatsink on a processor with no fan does no good. Same thing.

[mytekcontrols]

Yep I saw the same thing when I went to water cooling on my AutoC. Still needed a fan to blow air past the compressor (also a rotary), in order to keep the discharge temperature reasonable. Made a 25C difference in my case. The fan need not be very big, 80-100 CFM is probably sufficient for this purpose.