I am a freeze dryer maker, recently I designed a pilot f fryer with r508 cascade to reach _80 , my attampt was failed.high presser works well .my Low presser pipe lenght is 50meter and also I have a receiver tank with ,7 liter volume. I could not get blow _10 cc even I loaded 4 kilo gramm r 508 refrigerant, I am really stuck, do someone has a procedure for r508, including a safe guidline for r508 charging manner