Process Cooling System Chiller and Tower Sizing Formulas

  • TOWER SYSTEM DESIGN FORMULAS
  • Cooling Tower = 3 Gallons per Minute per ton
  • 1 Tower Ton = 15,000 BTU/hr
  • Tower Ton = GPM x ΔT/30
  • CHILLER SYSTEM DESIGN
  • Chiller = 2.4 Gallons per Minute / ton
  • 1 ChillerTon = 12,000 BTU / hr
  • Chiller Ton = GPM x ΔT / 24
  • LOAD SIZING FOR INJECTION MOLDING APPLICATIONS : MATERIAL
  • 30# / hr H.D. Polyethylene = 1 ton
  • 35# / hr L.D. Polyethylene = 1 ton
  • 35# / hr Polypropylene = 1 ton
  • 45# / hr PVC = 1 ton
  • 50# / hr ABS = 1 ton
  • 50# / hr Polystyrene = 1 ton
  • 40# / hr Nylon = 1 ton
  • 35# / hr Acrylic = 1 ton
  • 40# / hr Polyurethane = 1 ton
  • 50# / hr Acetal = 1 ton
  • 40# / hr PPO = 1 ton
  • 40# / hr PET = 1 ton
  • 50# / hr Polycarb = 1 ton
  • LOAD SIZING FOR INJECTION MOLDING APPLICATIONS : MACHINE
  • Hydraulics = .1 ton/Horsepower
  • Feed Throat = 1/2 ton each
  • LOAD SIZING FOR EXTRUSION APPLICATIONS : Pipe, Profile, and Sheet
  • MATERIAL
  • 50# / hr H.D. Polyethylene = 1 ton
  • 50# / hr L.D. Polyethylene = 1 ton
  • 50# / hr Polypropylene = 1 ton
  • 75# / hr Polystyrene = 1 ton
  • 70# / hr PVC = 1 ton
  • MACHINE
  • Extruder Barrel = 1 ton/inch of screw diameter
  • Gear Box = 1 ton / 100 HP
  • Feed Throat : diameter is < 3" = 1 ton
  • Feed Throat : diameter is > 3" = 2 ton
  • Air Ring Cooling @ 105 CFM = 1 ton (50°F air @ 78°F WBT)
  • LOAD SIZING FOR BLOW MOLDING APPLICATIONS
  • MATERIAL
  • 40# / hr Polyolefins = 1 ton (minimun Flow is 4.8 GPM / ton)
  • MACHINE
  • Hydraulics = .1 ton / inch
  • Feed Throat = 1/2 ton
  • LOAD SIZING FOR OTHER EQUIPMENT
  • Air Compressors with no after cooler = .1 ton / HP
  • Air Compressor with after cooler = .2 ton / HP
  • Vacuum Pump = .2 ton / HP
  • Machine Tools = .2 ton / HP
  • Water-Cooled Chiller = Each ton of chiller requires 1 ton of cooling tower
  • Mold Temperature Controllers = 1.2 ton per zone + .2 ton/horsepower (heating)
  • Mold Temperature Controllers = use PPH chart + .2 ton/horsepower (cooling)
  • Spot Welders = 1/4 ton per tip (for chilled water)
  • Plating Baths = Heat removal (BTU / hr) = DC amps x DC volts x 2.56
  • Mold Room Heating = 25 BTU / sq.ft. with 16' ceiling
  • Non Mold Room Heating = 50 BTU / sq.ft. with 16' ceiling
  • Mold Room Air Conditioning = 80 sq.ft / ton with 16' ceiling
  • LOAD SIZING FOR DIE CASTING
  • Zinc = Heat removal (BTU / hr) = M x 95 BTU / lb
                 M = throughput rate (lbs / hr)
                 Pour at 800°F
                 Remove at 300°F
  • Aluminum = Heat removal (BTU / hr) = M x 325 BTU / lb
                         M = throughput rate (lbs / hr)
                         Pour at 1200°F
                         Remove at 900°F
  • CHILLER CAPACITY LOSS
  • For each 1°F below 50°F LWT = 2% loss of rated chiller capacity

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