AR503-GR3/4-GCI Diaphragm Pump


The AR503-GR3/4-GCI is a medium pressure, three diaphragm pump assembly that is popular in the lawn care industry. 

GR3/4-GCI version Gear Reduction AR1636 with 3/4" Hollow Shaft and RM40 Control Unit

  • Parts in contact with pumped liquids in plastic-coated aluminum and body in aluminum
  • Diaphragms in NBR, Desmopan or Viton
  • Seals in NBR or Viton
  • Die-cast casing with oil-immersed mechanism and clear plastic tank for visual level checking
  • Pistons with ring for a more efficient “oil cushion” system to protect the diaphragm
  • New-design diaphragm cut-out system to prevent contact tearing even in heavy-duty operating conditions
  • Spherical sector profile valves for lower flow resistance and improved volumetric efficiency

The AR503-GR3/4GCI is a direct replacement for the Hypro D503. 

The GRGI model allows the D503 to be connected to a 4-6.5 HP gas engine with a 3/4" shaft.

**This item ships direct from the manufacture. Please allow 24-48 hours for shipping. 

Common replacement parts include:

Diaphragm Kits:
AR43297 - Blueflex
AR43295 - Desmopan
AR43294 - NBR

Valve Kits:
AR1987 - Valves

O-Ring Kits:
AR1984 - O-Rings

AR64532 - Oil

AR503 Manual 

AR503-GR3/4-GCI Specifications:

Max GPM: 14.3 GPM

Max PSI: 580 PSI

Max RPM: 3600 RPM

Max Fluid Temp.: 140 F

Diaphragm Material: BlueFlex

Inlet Barb: 1 1/4"

Outlet: (2) 1/2" & (1) 3/4" bypass

Weight: 42 Lbs

Oil Capacity: 32 oz

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