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  • 316SS or PVC liquid head materials of construction
  • Max. temperature (contact factory for higher temperatures):
    • 316SS: 200°F
    • PVC: 125°F
  • 0.80 to 18 gph (3.03 to 68 L/h) capacity
  • PTFE diaphragm
  • 1,100 psi max. discharge pressure
  • FKM O-ring as standard
  • 1/3HP-1ph-115VAC-60c-TEFC standard motor


The Neptune 500-A Series Chemical Metering Pump features a variable Oil By-PassTM stroke adjustment mechanism that will allow better valve performance than variable linkage designs. The valve checks have extra time to seat even in heavy liquids since they are idle during the by-pass portion of the suction and discharge strokes. The 500-A Series is only available in a simplex configuration.

The 500-A Series pump includes a ten-turn micrometer dial calibrated in 1% increments, with a bright color-contrasted dial protected from corrosion by a clear PVC covering. The stroke mechanism moves only when an adjustment is made, eliminating wear. The piston is powered through complete stroke length at all capacity adjustments, eliminating the stress, wear, and shock of lost motion designs. 

The standard, integrally-mounted motors are totally enclosed, fan-cooled, and include built-in automatic thermal overload. An internal relief valve automatically protects the piping and system from overpressure. The EZE-CleanTM valve system allows the valve to be removed for cleaning without disturbing the piping to the pump.