Aha
This project has been done now, it running well.
Not a DX control, it uses 8 flooded evaporators.
This system is consist of 4 compressors, 2 evaporative condensors, 2 liquid receivers, and 8 evaporators.
Results as following:
O ring is Viton.
Don't use drier-filter.
......
Thanks all.
This forum is great to me!