Pressures from 165 to 38425 PSI

L-D pumps are double acting versions of the workhorse L series pumps.
Unit of Measure

Pressure Ratio

N/A 1:10

Maximum Outlet Pressure

N/A 1,450 psi

Displacement Per Cycle

N/A 10.98 in³

Inlet (2) Connection (FNPT U.N.)

N/A 1 in

Outlet (2) Connection (FNPT U.N.)

N/A 1/2 in


N/A 48 lb

Air Drive Pressure

N/A 15 to 145 psi

Body Material

N/A Stainless Steel

Plunger Material

N/A Stainless Steel

Seal Material

N/A Ultra-High Molecular Weight Polyethylene (UHMWPE)


  • Easy to install and operate
  • Pressure maintained without energy consumption
  • Explosion proof, no electrical power required
  • Pilot air control for remote operation standard on many models
  • External spool valve for quick maintenance on most models
  • Dry air spool valve option available for severe service applications
  • Chemical service pumps are standard with separation fitting
  • Optional seal materials, port connections, double acting, multiple air heads, single stroke, adjustable stroke, special pumps, just ask
  • L-D pumps deliver approximately 50% more flow with less pulsation.
  • All are single air head style, 8 pressure ratios available.
  • Stainless steel bodies and plunger with UHMWPE (Ultra-High Molecular Weight Polyethylene) seals and Fluorocarbon (FKM)2 O-rings (-VE).
  • L10D - L35D pumps are standard with bottom inlet. For side inlet add-S.
  • L60-DS - L250DS pumps are only available with side inlet.
  • Operating pressure range is 15 -145 psi.
  • For air control option add - ACP to the catalog number.
  • All L-D pumps come with an unregulated pilot port, 1/8" FNPT. This standard feature allows easy on/off pump control with a very small valve or pilot switch.

Maximator® Liquid Pumps

N/A Air Driven from 60 PSI to 60000 PSI
Maximator® high efficiency pumps are ideal for a broad variety of oil, water and chemical applications. They feature a large air piston joined to a smaller diameter plunger. The pressure ratio is the ratio of these two areas and is the method of determining maximum output pressure. Higher pressures are obtained by using higher pressure ratios. Maximator® model numbers reflect the pump's nominal pressure ratios, while the technical data indicates exact ratios

Maximator® hydraulic pumps cycle automatically. The pump stops automatically when the output pressure forces and the air drive forces are equal. The pump restarts with a slight drop in the outlet pressure or an increase in the air drive pressure.

How to Select a Maxpro Pump

  1. Consider the type of fluid to be pumped and compatible materials.
  2. Know the available minimum plant air pressure.
  3. Determine the required outlet pressure.
  4. Determine the required flow rate.
  5. Feel free to consult your distributor or MAXPRO for application assistance.
Flow rates for each pump, at various air drive pressures and outlet pressures, are provided in the catalog. These pumps run very rapidly at no load and slow down as pressure increases. The pump will eventually come to a stop at the "stall" pressure, which is the air drive pressure times the pressure ratio of the pump. At this "stall" point there is no flow and no air consumption. The pump will hold the outlet pressure indefinitely and will only stroke if the outlet pressure drops or the air drive pressure is increased.

Installation and Maintenance

  • Maximator® pumps can be installed in any position, but vertical is best for longest seal life.
  • All connections to the pump, both liquid (inlet and outlet) and air drive lines, must be run with equal or greater size than the connections to the pump.
  • The maximum recommended height of a pump suction above the fluid level is 10 ft. for LO and L pumps, 7 ft. for S pumps, and 3 ft. for PPO and PP pumps. Operate pump slowly during initial prime.
  • Drive air should be filtered between 5µ and 4µ and have a maximum dew point of 50ºF. Very wet air will wash out lubricant and cause exhaust icing. Very dry air (dew point below 0ºF) will dry out lubricant and cause premature failure of spool o-rings and requires the use of Dry Air Spool option.
  • Pumped liquids should be filtered at 100µ or better, viscosity between 1-100 est.
  • Pump performance is affected by many operating conditions. Extreme temperatures, pressures, and high duty cycles will increase maintenance frequency.
  • All units are lubricated at the factory with silicone free semi-synthetic grease. After 2-3 months of normal (50% duty) operation, the standard spool seals should be inspected for wear and relubricated. Based on this inspection, future maintenance intervals can be planned and further disassembly and lubrication of other moving seals may be necessary. Optional Dry Air Spool seals require less maintenance.
  • MAXPRO® offers complete technical and service support for all Maximator® pumps. Customer service is our priority


  • Air drive inlet connection on all L-D pumps is 1/2" FNPT.
    Air pilot connection is 1/8" and is required for operation.
  • Maximum allowable liquid temperature is 140ºF.
  • Air section temperature rating: 0ºF to 140ºF.
  • The 9/16" -18 is a 1/4" O.D. tubing, high pressure coned and threaded connection.
  • Consult factory for L-D pump dimensions.
  • Fluorocarbon (FKM) is a registered trademark of E.l, DuPont de Nemours & Co. Inc