How to select the collect suction pipe line size ?

Hi engineers , please tell me how to select the correct suction pipe line if the unit cooler outlet is bigger than compressor inlet. thank you !

Turn the compressor around 180degrees and use that line

Dont worry about the outlet pipe sizes of either. Use the pipe size that will give you the best balance with pressure drop and velocity for oil return. There are charts and programs available which are less tedious than hand calculations. Sporlan has one on its' selection software. I would ignore Wambats' suggestion he hasn't learn to spell wombat yet. An Australian marsupial not known for being the sharpest tool in the shed.

Hi,

Refrigeration piping is not like water piping. You have to be very careful.
Two things to consider simultaneously, pressure drop and oil return (specially for vertical risers).
DO NOT USE THE SAME PIPE SIZE AS THE COMPRESSOR VALVES. MOST OF THE TIMES IT IS WRONG.
I suggest that you first learn how to size the pipes with tables then use a software.

Try using a suction accumilator (works in a similar way to an oil separator) gas goes into a "pot" and exits through the top of the "pot" into your suction side of the compressor this works well for preventing liquid returning to your compressor
however as has been previously stated by the other guys, a proper pipe sizing program is best