Low temp R-507 oil return issues

[techwizard007]

If you are rea lconcerned with the oil issue you can add a oil level saftey switch to the unit.
Regards

[foxtrot]

A oil safety switch would be an idea but if the oil gets low and it shuts off then lost product is a serious issue.

On the topic of oil seperators, I know that they are not 100% but wouldn't what little oil that made it through come back easier since its not turning into a large blob with the rest.

Would the bulletproof route be use a oil separator like a helical or coalescent the feed into a oil level controller like a Parker PL60CH. That way the oil level will be the same in crankcase even if a slug comes in?

I still plan on swapping out riser with 5/8" but would like the oil level pretty close to bullet proof.

Thoughts ?

[cmclifton]

On the topic of oil seperators, I know that they are not 100% but wouldn't what little oil that made it through come back easier since its not turning into a large blob with the rest.

In a word, no.

Longer answer -I work on a lot of systems that run low and ultra low temps on 507. All with oil separators. What oil does get through the separator just sits out there until it builds up enough to get pushed back to the compressor in a rush after an off cycle. If your off cycles aren't bringing all the oil back now, they won't bring it back with a separator installed.

[Andy Schoen]

What oil does get through the separator just sits out there until it builds up enough to get pushed back to the compressor in a rush after an off cycle. If your off cycles aren't bringing all the oil back now, they won't bring it back with a separator installed.

Words of wisdom.

[indy2000]

I don't believe you have an issue with oil return, if it ran a week.

You maybe are seeing it, just before defrost.

We run r-507 exclusively in low temp application (-40 sst) without oil return issues.


what is the box temp you are after?

[foxtrot]

Just a negative -10F freezer, nothing extreme.

[indy2000]

checking on PMs should be good enough for now.

[Freezeking2000]

What temperature are you running the box. I bet at -30 evaporator the load is 6K or less. You may need a 5/8" suction or warm up the box. Be sure your super-heat is on the money to keep the load up.

I would leave it as is.