Daikin Single Screw Compressor

Hi guys, I am a newby here and wish to throw out a question. I have had two 250kw Daikin compressors fail, both with damage to the star gates. The rotating sections that drive onto the screw both have scouring on the flat sides. Both had seizures after a short run time, one on low load and one on full load. How do they achieve capacity control and does anyone have some pictures of the internals. Are these normally a robust machine or do they have inherant problems, I thank you in advance for any information I can get, Denis.

These compressors are usually bullet proof and last for years. There are 2 types of capacity control on Daikin chillers, newer units have a copacity contol motor (stepless control). Older units have 3 or 4 solenoid valves (step control). Both use a sliding vain that is actuated by discharge gas. Gate rotar damage would only occur due to over heating (thermal expansion of screw) or liquid pumping which can break the gate rotar fingers. Your problem sounds like over heating, was the unit fully charged with refigerant? never operate these units with less than 70% of refrigerant charge and then only operate at 40% capacity until you have a full charge. I would also check the liquid injection is operating ok, there is a 3/8" pipe entering the top of the compressor which coninually injects during operation to cool the screw/gate rotars.

Hello, everyone! I have DAIKIN single screw ZHC5WLGYE with PVE oil DAPHNE FVC68D.
Tell me, please, can i use POE oil (for example ICI Emkarate RL 68H) instead of DAPHNE.
Thank you.