Suction Line Design and Installation

• Common Goal limit Suction Line Pressure Drop of 2 F (pressure equivalent)

Goals:

• Ensure oil return t compressor under all load conditions
  
  
• Prevent oil draining from active to inactive evaporator
  
  
• Prevent liquid refrigerant from draining back to the compressor during off-cycle
  
  
• Prevent unnecessary heat gains and line sweating
  
  
• Ensure a minimum gas velocity of 500 fpm. for horizontal runs
  
  
• Ensure a minimum gas velocity of 1000 fpm for vertical runs
  
  
• Ensure a max velocity of 4000 fpm is not exceeded
  
  
• A trap at the base of all suction risers (good to 25 ft)
  
  
• User double suction riser if system capacity can be reduced to 50% of full load
  
  
• Ensure high compression ratio’s are avoided
  
  
• Pitch all horizontal runs ½” per 10 ft. in the direction of flow
  
  
• Use loops to the top of the evaporator for non-pump down systems
  
  
• Ensure 18” of suction line within conditioned space
  
  
• FOLLOW CODE REQUIRMENTS
  

Common Suction Header

• Priority is free draining if suction headers

Shared Oil

• oil must be shared by multi compressor systems with common suction headers and common discharge (without oil separator)