6 HP Pump G Series • MLP-28/46S
2
Introduction
This brochure should be read in conjunction with Catalog MLP-46 and the assembly drawings when
supplied as part of the O/M manual with a pump.
Installation
The Haskel pump can be mounted in any position and should be secured to firm base using the mounting
brackets. If aggressive fluids are to be pumped then it is recommended that the drain in the 51910 bottom
cap and the vent in the distance piece (if included) are facing vertically downwards to prevent migration of
fluid into the air drive section. Do not pipe vent port back to fluid source.
Air Drive System
The air drive requires a minimum pressure of 25 psi to actuate the air cycling valve spool*. The maximum
air drive pressure is 125 psi. It is not necessary or desirable to use an airline lubricator. The air drive
section of all Haskel liquid pumps are prelubrjcated at the time of assembly with Haskel lubrication 50866.
The air drive requires no other means of lubrication. Install an air line filter and pressure regulator with a
minimum of 3/4” NPT port size. Also review air system upstream and eliminate any restrictions to provide
3/4” minimum inside diameter. Install a shut-off/speed control valve, 3/4” NPT, at pump inlet port. Install
two 1-1/4” NPT exhaust mufflers, p/n 21710, to the two female ports on the air valve to suppress the
noise and prevent entry of contamination into the air valve assembly. See “Air Controls” in MLP-46
catalog for typical layout. At high cycle rates the exhaust air can be 90°F (50°C) colder than the ambient
air. Continuous duty can cause icing of the exhaust mufflers. This can be reduced by using air dryers or
injecting alcohol or anti-freeze into the air drive.
* Pump may be modified to operate with <25 psig drive pressure. Specify 51875-1 after base part number
(e.g. GSF-100-51875-1).
Hydraulic System
See page 5 for fluid inlet/outlet port sizes. The -12 ratio G pump is a completely balanced double ended
unit. The -35, -60 and -100 ratio pumps are double acting output, single acting suction units. The piston
head contains an integral check valve.
NOTE: Inlet fluid supply piping should not be less than 1” I.D.; restricting the fluid supply will result in
lower outlet flow rates and cause pump to cavitate.
Larger internal diameter piping should be used with heavy fluids or if suction lift is >3 feet. The piping may
be somewhat smaller if the inlet is supercharged.
CAUTION:
HIGH PRESSURE LIQUID CAN BE DANGEROUS IF IMPROPERLY HANDLED.
Caution:
Do not loosen liquid inlet or liquid outlet fittings of pump to facilitate make up of piping
connections. These fittings must be tight to avoid leakage or damage. For the -35, -60 and -100 models, it
is recommended that suitable rated flexible hoses, or (preferably) a direct connection to the tank, be used
as the final connection to the liquid inlet to absorb the pumps pulsations and protect any rigid piping in the
system. A suction filter must be installed in the liquid inlet line. 100 x 100 mesh is normally ample to
protect the pump seals and check valves.
NOTE: See curves on page 3 and/or label on pump for safe maximum pressure ratings.
Priming
The pump will automatically prime itself if cycled slowly with the outlet port open to atmosphere or back to
tank. On initial start, or if suction line has been drained, the pump should be cycled under no load to
remove all air from suction line.
Operation
The pump model number indicates the ratio between the area of the air piston and the liquid piston. See
“Principle of Operation” in the MLP-46 catalog.
