Dorrco Positive Displacement Pumps

Dorrco® Pumps Are Rugged Duplex Diaphragm Pumps Which Permit Stroke Adjustment While In Operation

Dorrco Pump

Dorrco® Pumps

Designed by Dorr-Oliver expressly for handling the thickened underflow from sedimentation units. Dorrco positive displacement double diaphragm pumps are constructed of extra heavy-duty materials for tough, long-lasting service in extreme environments. These pumps can be installed at liquid level in thickener applications to prevent flooding or start-up problems. The pump operates with a smooth action, which prevents agitation and keeps the slurry from degrading during transport. Dorrco pumps come in two series: Type W and VM


The Dorrco pump enjoys many advantages over centrifugal pumps used in heavy-duty service. Because drive motion is at right angles to the diaphragm, you can expect the diaphragm to have a greater life. Anti-friction ball bearings also provide for a smooth pumping action which reduces friction and wear on moving parts. The Dorrco pump utilizes standard horizontal electric motors for lower power consumption. A stroke adjustment handwheel allows for easy adjustment of stroke length to vary discharge rate while the pump is operating. All components of the pump are above ground and easily accessed for maintenance.


Dorrco Pumps have been used successfully in metallurgical processes for over sixty years. The pump can be used with thickener and clarifier underflow, pulp mill liquors, slurries with heavy solids content, abrasive and corrosive alkaline or acid slurries. Flow ranges from 9 gpm (2M³/H) to 600 gpm (136M³/H) with multiple models are available for application selection. Protective rubber lining is also available for acidic/alkaline conditions.

Plunger Pumps
Plunger pumps have an outstanding history of lengthy service in the intermittent pumping of heterogeneous sludges. They are highly resistent to failure because of their rugged construction.

Type "S" Features

  • Ideal for water and waste treatment industries.
  • Sloping "kicker plate" prevents segregation of solids.
  • Large unobstructed waterways.
  • Raised, one-piece cast iron base plate.
  • Power transmission integral with pump assuring accurate alignment of gears and pump.
  • Deep stuffing box prevents leakage.
  • Weighted rubber ball valves are instantly accessible.
  • All bearings are replaceable, anti-friction ball bearings fitted for pressure lubrication.
  • Adjustable bronze bushed eccentric permits quick, easy stroke variations.

Diaphragm Pumps
Diaphragm pumps are applied when heavy density abrasive slurries must be pumped continuously and in large volume. Let's face it, the minerals industry is tough on equipment. So we make our "VM and W" pumps accordingly. With no "sissy" features.
Who expects a light-weight to do a heavy job? The Dorrco's are made of extra-heavy-duty construction to withstand the hard service they can expect.
Who can afford high horsepower, "prima-donna" motors? All you need to power the Dorrco is a standard electric motor.
Who has the time to turn a pump off just to vary the flow rate? The Dorrco design allows you to easily adjust the stroke to vary the discharge rate while the pump is running.
Who wants to hire an engineer just to run a pump? Our Dorrco's have a conveniently located stroke adjustment handwheel and calibrated stroke indicator that make it snap to keep a close check on the pumping operation at all times.
Who needs a centrifugal impeller that churns up flocs and abrades parts faster? Dorrco's are positive displacement diaphragm pumps - the action is smooth and parts won't wear out as fast.
Why would you ever want a pump on a tank base level? You can install the Dorrco's externally and adjacent to the thickener at liquid level. No flooding or startup problems.
When it comes to selecting the right pump for handling thickener underflows, choose Dorrco Diaphragm Pumps, used successfully in metallurgical applications for over fifty years.
Which Dorrco model will work best for you.
There are two models to consider, so let's get down to specifics. If your thickener flows are between 9 gpm and 90 gpm, choose the VM model. If your flows are larger between 40 gpm and 600 gpm, you're better off with the W model. However, there are some additional considerations that should be mentioned.
Certain applications require a more sophisticated handling of slurries, such as green liquor in pulp mills and acids in chemical processes. The VM model was designed with certain refinements to accommodate special transfers, such as a completely enclosed pumping system to prevent splashing and the ability to meter flows. It's a tidier pump for better housekeeping.
Now, if you need a beast of a pump, one that will transfer your underflow with a minimum of fuss and maintenance, you'll probably lean to the W model. It's exactly as we said before - tough, rugged and no slurry is too abrasive or too hard to handle.

"VM" Features: There are two sizes to choose from - the 2" and the 4". It's twin pumping chambers are each provided with individual suction and discharge vales. In appearance the VM looks like an inverted V-type automotive engine.
Here's how it operates. The twin plunger rods are moved alternately, directly up and down at right angles to the normal planes of the diaphragms by a rocking member, which is driven by a connecting rod that terminates in a crank on a horizontal counter shaft. A big plus - the stroke of the plunger rod and the rate of discharge may be changed at will while the pump is in operation. A calibrated stroke indicator dial and a pointer are provided to facilitate stroke adjustments.
It is driven by a standard motor that is connected to a counter shaft by V-belts and to the horizontal crank shaft by helical gear and pinion. All speed reduction is effected by the V-belt sheaves and gear train. This economical principle lets you use an easily replaceable standard motor rather than one of the more expensive, complex gear types.

  • Ideal for use in mineral processing industries with iron, cement, copper, coal, zinc, alumina, ores and brines.
  • Compact, sturdy, one-piece casting.
  • Rolling diaphragm action - longest life.
  • High mechanical efficiency.
  • No air trapping, no splashing.
  • Standard motor.
  • All bearings are anti-friction, ball type, and castings are of Meehanite, a special semi-steel possessing far better qualities than the conventional cast iron. Diaphragms are arranged at an angle to the horizontal to prevent air trapping.
  • Longer diaphragm life because the motion of the plunger rods is at right angles to the planes of the diaphragm. No sideways oscillation can take place to cause excessive mechanical wear.
  • Acid proof construction is optional, with a protective lining of rubber.

"W" Features: An extension of the VM pump line, the W covers the next range of sizes, 6" and 8". Because it is asked to do a heavier job, is was designed with similarities to the VM, but with a different pumping method.
Here's how it operates. The W pump has the inlet below and the outlet above the diaphragm, with the outlet valve located in the center of the diaphragm. The crank on the drive unit actuates a connecting rod which is secured to the rocker arm which in turn is supported by two bearing posts. The plunger rods alternately raise and lower the attached diaphragms. As the diaphragm is raised, the bottom inlet check valve lifts, permitting slurry to fill the cavity below the diaphragm. As the diaphragm is lowered, the lower check valve drops sealing the inlet opening. The top valve opens due to the pressure build-up in the chamber.
This duplex diaphragm pump is powered by a standard electric motor. As with the "VM", this economical principle eliminates costly and time-consuming specialty motor replacements. A conventional V-belt drive connects it to a variable speed drive unit encased in an oil-tight housing, permitting a stroke adjustment while the pump is operating.

  • Ideal for use in mineral processing industries with iron, cement, copper, coal, zinc, alumina, ores and brines.
  • Highest capacity.
  • Super-Duty gear box of ductile iron.
  • Electrically welded structural steel frame.
  • Bowls of cast iron 20.
  • Reinforced Neoprene and rubber diaphragms.
  • Rubber lined construction available.
  • The plunger stroke can be varied by an easy turn of the stroke adjustment handwheel, varying discharge rate within a six to one range, while the pump is in operation.
  • Cranks and anti-friction ball or roller bearings are used instead of power-consuming eccentrics and low efficiency sleeve bearings, for high mechanical efficiency.
  • Beaded-construction diaphragms are easily and quickly replaced.
  • The #8 duplex Type W will handle up to 75 cubic feet per minute of pulps, over 100 tons per hour.
  • Both discharge spouts are rubber-lined for maximum protection against abrasive action.
  • The wetted surfaces can be lined to protect the pump in corrosive applications.

"RM" Features

  • For use in Sugar Cane muds.
  • Simple, straightforward design.
  • Dependable, low maintenance operation.
  • Worldwide usage.
  • Sizes to match clarifiers.
  • Long service life.
  • Low cost.


Dorrco Positive Displacement Pumps are used in waste treatment facilities for viscous heterogeneous sludges, in mineral processing plants for transporting heavy slurries and in pulp paper mills and food and pharmaceutical factories when rotating impellers would not function satisfactorily.


Dorrco manufactures pumps to the highest quality standards at its factory in Hazleton, Pennsylvania, U.S.A. Dorrco has been manufacturing and selling pumps to serve communities and all industries for over forty years and warehouses an extensive supply of parts to provide immediate service.

Represented in Canada by:
ICR Water Technologies Inc.
3-200 Memorial Avenue, Suite 101
Orillia, Ontario
L3V 5X6
Phone or Fax to: (888) 281-7774

For more information on this product and to view the in-depth statistics please click here to read the full PDF brochure.