Rotary compressor third port??

[nike123]

Here I got photos of compressor which has third pipe. What could be use of that pipe? It appears that is connected to high side just before exit of gases.
Does anyone have technical data of this compressor?

[aeb200]

could be to balance oil when two compressors on same circuit (tandem)

If oil isn't balanced between compressors it will pump out of one into the other on startup

[nike123]

could be to balance oil when two compressors on same circuit (tandem)

If oil isn't balanced between compressors it will pump out of one into the other on startup

Not likely, it is on high side! Check second photo! And they are used as single compressor in MHI AC units.

[Gary]

On a rotary compressor the suction gas goes directly to the pump (which is why they have an accumulator on the side of the compressor). Everything inside the compressor (including the crankcase) is part of the high side.

[nike123]

On a rotary compressor the suction gas goes directly to the pump (which is why they have an accumulator on the side of the compressor). Everything inside the compressor (including the crankcase) is part of the high side.

Why is then this pipe connected direct to compression chamber near discharge part of chamber.

[Gary]

Why is then this pipe connected direct to compression chamber near discharge part of chamber.

I have no idea.

[Brian_UK]

It looks like an liquid injection line for compressor cooling.

I was going to say - "often found in Mitsubishi" and then looked back at the photo

[nike123]

It looks like an liquid injection line for compressor cooling.

I was going to say - "often found in Mitsubishi" and then looked back at the photo

It is connected to liquid pipe after condenser thru solenoid valve marked (at electrical diagram) "SV (for protection)" and capillary tube.
Now, if that is used as liquid injection (I also presumed that is what it is used for), how is possible that pressure in condenser is higher than pressure in that point of chamber after the liquid is passed thru that capillary tube?

Is it possible that such small distance from discharge port in chamber could make enough pressure difference to drive liquid refrigerant thru capillary.