Key Features About the Torpedo Pump

Key Features - Torpedo PumpOur pumps are currently installed in the most demanding locations around the world. If you need a proven pump system for high purity water for any application, the Torpedo Pump is the best solution for the following reasons:

  • Very high efficiency of up to 82% with a nominal of 72%. This efficiency is due to its multi-stage “turbine” design.
  • Very high energy efficiency which will save you month after month in lower energy bills.
  • No noise, due to the pump being in the water stream and inside the casing, there is no noise. You will have to check the pressure gauges to confirm if the pump is running.
  • No ongoing routine maintenance. Our design requires no bearings to maintain, no seals, no leaks, no scheduled preventative maintenance, which adds up to problem free operation.
  • Minimum skid space is required. The Torpedo Pump can be racked-up with the R.O. membranes.
  • Very easy retrofit capability. If you are using the Torpedo Pump in a retrofit application, you can leave the existing R.O. feed pump in place for standby service and pipe the new Torpedo Pump into the system in parallel with the existing pump.
  • Installation ease, you will have none of the alignment problems common to base-mounted pumps.
  • Motor heat is rejected to the R.O. feed water, raising the overall R.O. system efficiency.
  • 2 Gallon Per Minute – 1200GPM flow rate.

Torpedo Pump Custom Solution

Our multi-stage turbine pump and its motor are manufactured in stainless steel and shipped to you complete. Each pump and motor are mounted in a pressure vessel with inlet and outlet connections, and electrical cable connections ready for installation on your R.O. Skid.

We have been very successful with this pump in both new installations and in retrofitting existing R.O. systems. In many cases, we can reduce by 50% the required horsepower requirement. We have units in the field that have been in service for ten years with no downtime.

Pumps Unlimited

Our reputation for product quality, performance, reliability and value is unsurpassed.

  • 19 Affonso Drive
    Carson City, Nevada 89706
  • (775) 246-0847

Additional Information

Print this chart for ease of use and retain for future reference.

Model code: T30-15-30 means our model 30 pump with 15 stages and a 30 hp motor.

Differential Pressure

In Feet 289 346 404 462 520
In PSI 125 150 175 200 225
GPM Recommended Pump Recommended Pump Recommended Pump Recommended Pump Recommended Pump
4 T1-13-.5 T1-18-.75 T1-18-.75 T1-22-1 T1-26-1.5
6 T2-12-.75 T2-15-1 T2-21-1.5 T2-21-1.5 T2-21-1.5
10 T2-15-1 T2-21-1.5 T2-21-1.5 T2-27-2 T2-27-2
15 T3-14-1.5 T3-18-2 T3-24-3 T3-24-3 T3-38-5

Print this chart for ease of use and retain for future reference.

Model code: T30-21-25 means our model 30 pump with 21 stages and a 25 hp motor.

Differential Pressure 

In Feet 404 462 520 578
In Meters 123 141 158 176
In Bars 11.9 13.6 15.3 17.0
GPM M3/Hr Recommended Pump Recommended Pump Recommended Pump Recommended Pump
25 5.7 T8-30-7.5 T8-30-7.5 T8-37-7.5 T8-37-7.5
40 9.1 T8-37-7.5 T8-44-10 T8-44-10 T8-50-15
60 13.6 T17-14-15 T17-15-15  T17-15-15  T17-18-15

General Features

High Quality, Reliable Insulation Wire
The coil conductor itself is coated with high quality insulating materials with outstanding waterproof properties. Polypropylene insulation is generally used for water tight insulated magnet wire for submersible motors, A nylon sheath is used for mechanical protection over the Polypropylene insulation layer. We use specially developed denatured Polypropylene which offers very stable waterproof characteristics. The unique insulation structure is as a result of extensive development and has proven to be of a far superior quality. This results in long insulation life even under severe operating conditions.

Operating temperature of 95F in Water
The motors operate with a flow rate O.5 ft/sec. in water temperature up to 95F without any derating of horsepower. This 95F temperature is within NEMA standards. For applications where water temperature is elevated, consult Pumps Unlimited for a high temperature motor.

High Torque Characteristics
The high quality electrical grade silicone steel laminations combined with a unique design allow for voltage variations and high torque qualities of the submersible motor.

The rotor balance ring (one on each end of the rotor) allows for excellent dynamic balance for the rotating element of the motor.

Carbon Sleeve Bearings
Two carbon, water lubricated, bearings are used as guide bearings. These have an extremely large surface area which results in extra alignment and acts as a steady bushing.

Complete Corrosion and Water Tight Protection
All main motor components are made of 316, 304 or 304L stainless steel, this includes the casing/housing, the main shaft and all bolts.

Quality Control
All submersible motors are manufactured and tested under the most stringent quality control procedures. This assures that you receive a motor that will give you long service life and trouble free operation.

High-performance Thrust Bearing

The well established KINGSBURY design thrust bearing creates a wedge of water between the pivot shoe and carbon disc. Our innovative design permits high thrust loads to be placed on the bearings while showing no measurable wear after several years of severe duty operation. This allows for long pumping life, virtual trouble free operation and low maintenance. For all 8″ and 10″ motors, the 1,000 lbs. maximum continuous up-thrust is carried between the upper slide plate and the separate upthrust carbon bearing.

The Torpedo Pump uses submersible motors manufactured specially for Pumps Unlimited in 304 all stainless steel construction. These motors are typical of the motors that are used in deep well applications all over the world. When you put a well pump motor 1500 feet below the ground you want it to be reliable and maintenance free. That is what you get with a Pumps Unlimited Torpedo Pump. Our motors will run for a long time under water without attention.

The Pumps Unlimited submersible motor has a maximum efficiency of approximately 85%. Total pump efficiency is equal to the mechanical pump end efficiency multiplied by the motor efficiency. For the Pumps Unlimited multi-stage Torpedo Pump only, it has a very high efficiency of approximately 72%.

Comparing the efficiency of a Centrifugal pump with a Torpedo Pump you can see the value of a submersible pump:

A) A single stage end-suction centrifugal pump, with a mechanical efficiency of 60% and a premium efficiency motor of 92% has a total pump efficiency of (.6 x .92) or 55%.

B) The Torpedo Pump with a mechanical efficiency of 72% and a motor efficiency of 84% has a total pump efficiency of (.72 x .84) or 60%.

Using a TORPEDO PUMP will then save you several thousand dollars per year in electrical energy costs. Contact us and we will help you with your energy calculations.

The Torpedo Pump was originally designed for clients requesting low noise levels in reverse osmosis feed pumps. The Hewlett Packard Company was operating their RO systems in their facility’s basement right below the production floors. The noise from the old pumps were causing problems with the workers on the production floors. We built our first Torpedo Pumps to solve this problem for Hewlett Packard, since then we have gone on to become the gold standard for ultra quiet feed pumps in the microelectronics/semiconductor business, as well as the cogeneration, pharmaceutical, and beverage industries.

The reason that the Torpedo Pump is so quiet is that the pump and motor are running underwater. High-frequency sound cannot be transmitted through water, this is why submarines surface at night to send radio transmissions back to their bases. Only low frequency sound can be transmitted through water.

The Torpedo Pump is so quiet you have to check the pressure gauges to see if it is actually running. It is certainly below the noise level of the room and has been measured to be around 65 to 70 dbA. Eliminating noise is one of the main reasons why the Torpedo Pump is specified in more high-tech applications than any other RO Feed Pump in the industry.

Pumps Unlimited is a division of Facility Equipment Corporation and has been manufacturing TORPEDO PUMPS since 1982. Our feed pump installations for RO applications cover a broad range of industries from the semiconductor, power, food and beverage, pharmaceutical, and biotech to other “clean” type industries.

Our reputation for product quality, performance, reliability and value, is unsurpassed in the industry. Customer references are available upon request.

PUMP DESIGN: The TORPEDO PUMP is an in-line, multi-stage turbine pump that is directlydriven by a submersible electric motor. The pump ends are available in either stainless steel or cast iron. Motors are available in either epoxy coated steel or stainless steel. Both the pump and motor are encapsulated in a fiberglass or stainless steel pressure vessel. All the quality components are designed to give many years of reliable service without maintenance.


1.1 Operating Ranges

The feed pump shall be available in sizes to accommodate design flows from 1 to 1200 gpm with discharge pressures up to 822 psi (1900 feet).

1.2 Feed Pump Design

The feed pump shall be a high efficiency unit designed to meet the maximum pressure and flow conditions, with minimum brake horsepower required.

1.3 Feed Pump Noise Levels

Feed pump sound levels shall not exceed 70 decibels (dbA) within six feet of the unit.

1.4 Feed Pump Mounting

No special foundation shall be required for mounting the feed pump. The feed pump shall be capable of being mounted on a membrane rack, wall, saddles, or suspended from pipe-hangers.


2.1 Pump-end Design

The pump shall be a multi-stage, in-line turbine pump.

2.2 Pump-end Mechanical Efficiency

The nominal design mechanical efficiency of the pump shall be 72%.

2.3 Pump-end Metallurgy

The pump shall be constructed of either all stainless steel or cast iron. No plastic components shall be used in the construction of the pump.

2.4 Pump/Motor Coupling

The pump and motor shall be directly connected to one another via a splined coupling.

2.5 Motor Design

The motor shall be either an all stainless steel submersible electric motor or an epoxy coated steel electric motor, 3600 rpm, and shall be either “wet wound” or “encapsulated” design. Motor thrust bearing shall be of the Kingsbury self-aligning shoe type.

2.6 Rejected Motor Heat

Rejected motor heat shall be directed to the feed water to pre-heat this water and raise overall system efficiency.

2.7 Motor Cooling

The motor shall be cooled by inlet process water and shall not require lubrication.

2.8 Feed Pump Containment

The pump and its motor shall be encapsulated in either fiberglass or stainless steel pressure vessel with stainless steel end plates. The pump and motor shall be supported uniformly within the pressure vessel, and the motor leads will pass through the discharge end plate via a watertight bulkhead sealing device.

The unit shall have a stainless steel vent valve to evacuate air from the pressure vessel prior to system start-up.

The inlet and discharge connections to the feed pump shall be ________ inch(es) in diameter. Connections shall be (victaulic, flanged, threaded, other) type.


The pump will be capable of pumping ________ GPM at a pressure differential of ________ PSI. Inlet water pressure to the pump shall be ________ PSI. Inlet water shall be pre-filtered and treated clean water with no particulates. Water temperature shall be ________ ° F.


The Reverse Osmosis System Feed Pump shall be manufactured by PUMPS UNLIMITED in Carson City, Nevada under the trade name TORPEDO PUMP.