Icebank cooler, beer line lengths

[Roys Refreshments]

Hi there,
I have a Celli Icebank 4 coil. Geo50VRL is the model. I know the coils are approx 20m. Just trying to work out if its ok to use 4mm ID beer line in and out, I guess my PSI will have to be raised right up to push beer through the coils distance and also is it recommended to use beer gas (70Co2 30Nitro) to avoid over carbing the beers if the PSI will be set above what the beer is carbed to?

Cheers,

 

[golfandbrew]

Use 6.3mm in. 4 mm is okay unless your font lines are 5mm. In that case use 5mm beer line. No need for beer gas mixture as your kegs will be ambient and will then require more CO2 to remain carbonated.