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A.N.S.I. Standard
American National Standards Institute. A set of specifications (envelope dimensions) for centrifugal pumps manufactured in the United States.

Connects and aligns the power end of an ANSI pump to the wet end.

Adjustable speed drive (ASD)
ASD describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control.

Affinity laws
They predict how capacity, head and horsepower are affected by changes in the centrifugal pump impeller diameter or shaft speed.

Air ingestion
Air is coming into the stuffing box because of a negative suction pressure.

The centerline of the pump is perfectly aligned with the centerline of the driver (usually an electric motor)

Ambient heat/pressure
The heat or pressure in the area where the equipment is located.

To soften the metal by heating it to a predetermined temperature somewhere below its melting point.



The best efficiency point. It is the point where the power coming out of the pump (water horsepower) is the closest to the power coming into the pump (brake horsepower) from the driver. This is also the point where there is no radial deflection of the shaft cause by unequal hydraulic forces acting on the impeller.

Brake horsepower. The actual amount of horsepower being consumed by the pump as measured on a pony brake or dynamometer.

Back plate
Used in some centrifugal pumps to position the stuffing box and provide an impeller wear surface.

Back pull out pump
A design that allows the wet end of the pump to be left on the piping when the power end and adapter are removed. A.N.S.I. pumps are designed this way.

Back to back double seal
The rotating seal faces are facing in opposite directions. The worst possible configuration. In the past this term was used to describe a higher barrier fluid pressure between dual mechanical seals.

Balance Ratio
A 70/30-balance ratio means that 70% of the seal face closing area is seeing the stuffing box pressure and 30% is not seeing the pressure.

Balanced seal
A design in which the seal face closing area is reduced to lower the closing force, and reduce the heat generation between the faces.

Metric term for one atmosphere of pressure.

Barrier fluid
The high-pressure fluid that is circulated between two mechanical seals. The fluid should enter the bottom and leave the top to prevent air pockets.

Barrier fluid
The high-pressure fluid that is circulated between two mechanical seals. The fluid should enter the bottom and leave the top to prevent air pockets.

Base Plate
The pump and motor mount on this unit. The pump and motor feet closest to the coupling should be doweled to the base plate.

Consists of an inner race, an outer race, and a series of balls between them. Often called a precision or anti friction bearing. Supports the rotating shaft and allows it to turn with a minimum amount of friction. Could be either sleeve or anti-friction type.

Bernoulli’s Law
A moving stream of liquid or gas exerts less sideways pressure than if it were at rest. The result is that things seem to be drawn into the stream, but the higher pressure from outside is really pushing them in

Brinnell hardness
A method of measuring the hardness of metal parts and hard seal faces. Above 350 the standard machining operations of turning, boring, drilling, and tapping become uneconomical.

Buffer Fluid
The low pressure fluid that is circulated between dual mechanical seals.

Buna N
Some times called Nitrile. A common elastomer used in the sealing of oil or water. Sensitive to Ozone attack and therefore has a short shelf life.

A close fitting support device used to restrict flow between two liquids, thermally isolate a hot liquid, support the rotating shaft, break down pressure etc. Commonly made of carbon or Teflon.

Bypass Line
Used to either re-circulate fluid from the pump discharge to the stuffing box, the stuffing box to the pump suction, or the pump discharge to a lower pressure point in the system.



C Frame Adapter
Used to connect and align the pump to the motor with registered fits. (imperial dimensions. Called the D frame adapter in the metric system).

Canned Pump
A non-seal pump with the shaft, bearings and rotor contained in a can to prevent product leakage. Limited to pumping clean lubricating liquids.

Fluid flow measured in gpm, liters/min, M3/hr. etc.

The compound formed when carbon combines with an element. The carbides of metal are very hard and are often used as a mechanical seal face.

Carbon Bushing
Used as a restrictive bushing in flushing applications, a thermal barrier in high temperature applications, a disaster bushing in an A.P.I. gland and to support a deflecting shaft in many mechanical seal applications

A common mechanical seal face material chemically inert to most fluids with the exception of oxidizers, bleaches, halogens and a few other fluids.

Cartridge Seal
A self-contained assembly containing the seal, gland, sleeve, and both stationary and rotating seal faces. Usually needs no installation measurement. Must be used if impeller adjustments are made. Cartridge seals are the standard for A.P.I. seal applications.

The formation of gas bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapor pressure. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation, and noninertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Such cavitation often occurs in control valves, pumps, propellers, impellers, the strike of a mantis shrimp and in the vascular tissues of plants. Noninertial cavitation is the process in which a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers, etc. Since the shock waves formed by cavitation are strong enough to significantly damage moving parts, cavitation is usually an undesirable phenomenon. It is specifically avoided in the design of machines such as turbines or propellers, and eliminating cavitation is a major field in the study of fluid dynamics.

Centrifugal Pump
A rotodynamic pump that uses a rotating impeller to increase the pressure of a fluid. Centrifugal pumps are commonly used to move liquids through a piping system. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from where it exits into the downstream piping system. Centrifugal pumps are used for large discharge through smaller heads.

A hard, chemically inert seal face material that includes products refereed to as silicone carbide.

Close-Coupled Pump
Pump with built-in electric motor, with the motor drive and pump impeller on the same shaft.

Cooling Jacket
Surrounds the stuffing box of the pump to control the temperature of the fluid in the stuffing box. Usually molded into the back plate.

The mechanical connector joining the motor shaft to the equipment to be driven.



D Frame Adapter
Used to connect and align the pump and motor (manufactured in metric dimensions). The Imperial version is called a “C” frame adapter.

Dayton Pump
In 1908 Frank M. Tait founded the Dayton Pump and Manufacturing Co., a firm that produced the world’s first completely automatic water system

Movement or displacement of the shaft in a radial direction.

Measured in gm/cm2 or lb./in 2 A measure of the weight of the fluid. A better term than specific gravity

Differential Pressure
The difference between the outlet pressure and the inlet pressure. Differential Pressure is sometimes Called the Pump Total Differential Pressure

Discharge Recirculation
Connecting a line from the discharge side of the pump to the stuffing box. Should be used with a close fitting bushing in the end of the stuffing box to increase the stuffing box pressure. A common application when pumping a fluid close to its vapor point.

Double Suction Pump
The rotor is suspended between two bearings with the fluid entering on either side of the impeller. Used at higher capacities.

Double Volute
A centrifugal pump design that incorporates two cut waters to prevent shaft deflection when the pump is operating off of the B.E.P. Lowers the efficiency of the pump and therefore seldom used on smaller size impellers.

Dry Running
Running without fluid at the seal face.

Dual Seal
Two seals running in various configurations: back to back, tandem, face to face, or concentric.

Dynamic head (system head)
The pump head created by friction in the piping system.

Dynamic Suction Lift
includes static suction lift, friction head loss, and velocity head.



Ethylene propylene rubber. The most common elastomer used in the sealing of water based and higher pH materials. Cannot be used in petroleum products

Power out of the equipment divided by power in.

A rubber like material that, when compressed and then released will return to 90% of its original shape in less than five seconds.

A process involving chemical change caused by the passage of an electric current through a liquid.

Eye of the impeller
The center of the impeller, where the fluid enters.



Full load amps

F.P.M. (fpm)
Feet per minute. When used in the context of seals it is measured at the center of the seal face

Face Combination
The materials chosen for the lapped seal faces. Usually a grade of carbon graphite running on a hard face material.

Face Flatness
Measured by an optical flat and a monochromatic light. The measurement is read in helium light bands (.0000116 inches or 0,3 microns).

Face Pressure
The sum of all the loads on the seal face including the spring load, hydraulic load and shaft axial thrust, divided by the area of the seal face. This face load is reduced by friction between the sliding elastomer and the shaft or sleeve.

Filled Carbon
Contains organic or inorganic materials that might be sensitive to temperature, or be attacked by the fluid you are sealing. Usually a low cost carbon.

A devise used to remove solid particles from liquid. It removes smaller particles than a strainer.

Fire Pump
A fire pump is a part of a fire sprinkler system’s water supply and can be powered by electric, diesel or steam. The pump intake is either connected to the public underground water supply piping, or a static water source (e.g., tank, reservoir, lake). The pump provides water flow at a higher pressure to the sprinkler system risers and hose standpipes. A fire pump is tested and listed for its use specifically for fire service by a third-party testing and listing agency, such as UL or FM Global. The main code that governs fire pump installations in North America is the National Fire Protection Association’s NFPA 20 Standard for the Installation of Stationary Fire Pumps for Fire Protection.

A rapid change in liquid state from a liquid to a gas.

Flexible Shaft
A shaft with an operating speed higher than its first critical speed.

Genetic term for the elastomer called Viton? Viton is a Dupont Dow elastomer product.

Putting an outside liquid into the stuffing box of the pump at a pressure higher than stuffing box pressure. All of this liquid mixes with and dilutes the pumped fluid

Created whenever pressure works on an area. The units are pounds. (F = P x A)

Fret or Fretting
Damage or grooving caused by the removal of the protective oxide that is formed on most corrosion resistant metals. It happens when a softer material (rubber) rubs against a hard shaft or sleeve. A common problem with low cost OEM mechanical seals and bearing grease or lip seals.

Friction Head
The pressure expressed in lbs./sq. in. or feet of liquid needed to overcome the resistance to the flow in the pipe and fittings

Friction loss
Refers to that portion of pressure lost by fluids while moving through a pipe, hose, or other limited space. FL = CQ2L Where FL = friction loss (expressed in psi) C = coefficient of friction (based on the inside diameter of the hose and the inside jacket material) Q = flow rate in hundreds of gallons (gpm/100) L = Length of hose in hundreds of feet (L/100)



The part that holds one half of the mechanical seal and attaches to the stuffing box.

Grunfos Pumps
Grundfos is one of the world’s largest manufacturers of pumps, providing water for homes, farms, commercial buildings, and industrial uses. Featuring unique stainless steel construction and the latest in electronics, Grundfos pumps are recognized for reliability and value throughout world-wide — wherever water moves. Grundfos maintains an extensive network of manufacturer representatives, distributors, and dealers to serve customers nationwide.



Hard face
A seal face either rotating or stationary. The most common materials are silicone carbide, ceramic, tungsten carbide, Stellite, Ni-resist. The hard face must be the wider seal face.

Harmonic vibration
Vibrating in harmony with something near by. This can be a big problem for bearings in stationary or nonrunning equipment.

Abbreviation for `hazardous material’

(1) A measure of the energy possessed by water at a given location in the water system expressed in feet; (2) a measure of the pressure or force exerted by water expressed in feet.

The equivalent height of the liquid. 20 C. Water is used, as the standard where 10 meters (33.9 ft.) of water equals one atmosphere (14.7 psi. or 1 bar). The term head is used instead of pressure in the centrifugal pump business.



Inland Counties Water Association.

A rotating component of a centrifugal pump, usually made of iron, steel, bronze, brass, aluminum or plastic, which transfers energy from the motor that drives the pump to the fluid being pumped by accelerating the fluid outwards from the center of rotation. The velocity achieved by the impeller transfers into pressure when the outward movement of the fluid is confined by the pump casing. Impellers are usually short cylinders with an open inlet (called an eye) to accept incoming fluid, vanes to push the fluid radially, and a splined, keyed or threaded bore to accept a drive-shaft.



JDL Pumps
Currently, JDL Systems is a manufacturer of Sump, Sewage, and Domestic Water Booster Systems.

A metric unit for the measurement of heat. Defined, as the energy required to move one Newton over one meter.



An “elastomer like” material manufactured by E.I. Dupont that is used to seal most solvents and other aggressive fluids. It is available in several different grades.



Lantern Ring
A device used to supply lubricant to packing. Usually located in the middle of the packing ring set.



Magnetic Drive
A type of seal-less pump that is most often limited to pumping clean lubricating liquids. Similar in concept to a canned pump.

Iron oxide (Fe3O4). Protective coating that forms on iron pipe to prevent further rapid corrosion. Usually black or maroon in color. Can be very destructive to mechanical seal components until the oxide stabilizes. We often find these iron pipes in new hot water systems

Mechanical Seal
Mechanical assembly that forms a leak proof barrier between flat, rotating surfaces to prevent high-pressure leakage.

Mean Time Between Failure

Multistage Pump
A centrifugal pump containing two or more impellers is called a multistage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. If we need higher pressure at the outlet we can connect impellers in series. If we need a higher flow output we can connect impellers in parallel.

Myers Pumps
The tradition of excellence that began with our dependable double-acting hand pumps in 1870 continues today with innovative designs for a diversified product offering. As a part of Pentair Water, Myers continues to set the standard for quality, value, and reliability



The net positive suction head available to prevent cavitation of the pump. It is defined as atmospheric pressure gage pressure static pressure -vapor pressure – friction loss in the suction piping.

Net positive suction head required to stop a pump from cavitating. The pump manufacturer gives this number to you. Since testing with cold fresh water generated the number, it can be lowered in some cases if you are pumping hot water or some hydrocarbons.

Net Positive Suction Head (NPSH)
NPSH parameter shows the difference between the actual pressure of a liquid in a pipeline and the liquid’s vapor pressure at a given temperature.



Outside diameter.

Operating length
Measured after the seal has been compressed the proper amount. The measurement is usually made from the face of the stuffing box.

Combines with carbon to form carbon monoxide or carbon dioxide. The oxidizers attack all forms of carbon including the seal face and any black O-rings in the syste

Created by oxygen atoms combining with oxygen molecules in a high-energy atmosphere. Will prematurely age Buna rubber. Ozone forms in the shop as a result of the sparking of electric motor brushes.



The soft rings that mechanical seal replace to stop leakage. Packing must leak because it works on the theory of a series of pressure drops to reduce the stuffing box pressure to the point where the leakage is acceptable. A minimum of five rings of packing is required to do this.

Paco Pumps
Since 1907, originally Pacific Pumping Company (Pacific Pumps) PACO Pumps has been servicing the needs for fluid movement through their commitment and focus on the pumping needs of users in all markets. They manufacture the world’s most complete lines of end suction, in-line, split case, non-clog, sump pumps, special purpose pumps, and pumping systems. Now owned by Grundfos Pumps.

Pipe Strain
The strain on the pump volute caused by the piping. It will cause excessive mechanical seal movement and can cause contact between rotating and stationary pump and seal components.

Power end
The end of the pump that attaches to the power source and does not get wet from the pumpage. The bearings are in this part.

Predictive Maintenance
Scheduling maintenance activities only if and when mechanical or operational conditions warrant by periodically monitoring the machinery for excessive vibration, temperature, lubrication degradation or observing any other unhealthy trends that occur over time.

Pressure Head
A measurement of the amount of energy in water due to water pressure.

Preventive Maintenance
Scheduling maintenance activities at predetermined time intervals where you repair or replace damaged equipment before obvious problems occur

The action of starting the flow in a pump or siphon.With a centrifugal pump, this involves filling the pump casing and suction pipe with water.



The introduction of a fluid outside the seal to cool the product, or dilute any leakage across the seal faces.



Required Head
Required Head Formula : Required Head= Pipe Friction Loss +/- Altitude Change +/- Static Pressure Change.

Rotating seal
When the spring loaded or moveable portion of the seal rotates with the shaft.

Run out
Twice the distance that the center of the shaft is displaced from the axis of rotation.



Sandpiper Pumps
The name SANDPIPER originated during the development of the first Air Operated Double Diaphragm (AODD) pump by Warren Rupp. AODD pumps were designed to handle solids of any appreciable size. To accelerate wear during the development of the pump, a slurry of very abrasive silica sand was continuously cycled through the pump. The sand slurry often wore through the piping before the pump failed. Since the sand was pumped through a pipe, Warren E. Rupp, the company founder, named the pump the SANDPIPER.

Shallow Well
is any source of water where the water is within 25 feet of ground level. When water is pumped from a well the water level will draw down. The lowest level to which it will drop is the level from which it must be pumped.

Specific Gravity
Direct ratio of any liquid’s weight to the weight of water at 62 deg F. Water at 62 deg F weighs 8.33 lbs per gallon and is designated 1 sp. gr.

Static Suction Lift
is the vertical distance from the center line of the pump down to the free level of the liquid source.

Submersible Pump
Is a device which has a hermetically sealed motor close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. Submersible pumps push water to the surface as opposed to jet pumps having to pull water. Submersibles are more efficient than jet pumps.

Suction Lift
Exists when the source of supply is below the center of the pump.

Sump Pump
A sump pump is a pump used to remove water that has accumulated in a water collecting sump pit, commonly found in the basement of homes. The water may enter via the perimeter drains of a basement waterproofing system, funneling into the pit or because of rain or natural ground water, if the basement is below the water table level. There are generally two types of sump pumps: pedestal and submersible. The pedestal pump’s motor is mounted above the pit, where it is more easily serviced but also more conspicuous. The submersible pump is entirely mounted inside the pit, and is specially sealed to prevent electrical short circuits.

System curve
A description of what the pump is required to perform. The pump will pump where the system curve intersects the pump curve.



Taco Pumps
Taco, Inc., headquartered in Cranston, RI, develops and manufactures hydronic-based components for use in heating and cooling applications across the building spectrum–residential, commercial, industrial and institutional. Its wide range of hydronic and radiant systems and components include pumps, heat exchangers, expansion tanks, flow measurement devices, air separators and valves, and zone control products. It is also one of the best-known brands in the hydronic industry, long associated with continual product innovation and development.

Total head
The amount of head produced by the pump. Discharge head minus suction head. If suction head is a negative number it is added to the discharge head.



“Underwriters Laboratory” tests electrical components and equipment for potential hazards. When something is UL-listed, that means that the UL has tested the device, and it meets their requirements for safety – ie: fire or shock hazard.

Unbalanced seal
Not hydraulically balanced to generate low heat at the seal faces. Typical of original equipment designs.



Valley Pump Group
1984 Valley Pump Group was purchased by the Mueller Pump Co., of Decatur, Illinois.

Variable Frequency drive (VFD)
Is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. A variable frequency drive is a specific type of adjustable-speed drive. Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-speed drives (VSD), AC drives, microdrives or inverter drives. Since the voltage is varied along with frequency, these are sometimes also called VVVF (variable voltage variable frequency) drives. Variable-frequency drives are widely used. In ventilation systems for large buildings, variable-frequency motors on fans save energy by allowing the volume of air moved to match the system demand. They are also used on pumps, elevator, conveyor and machine tool drives.

Variable Speed Drive (VSD)
VSD describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control. Where speeds may be selected from several different pre-set ranges, usually the drive is said to be “adjustable” speed. If the output speed can be changed without steps over a range, the drive is usually referred to as “variable speed”.

Velocity Head
A measurement of the amount of energy in water due to its velocity or motion.

Property of a liquid that resists ant force tending to produce flow. It is the evidence of cohesion between the particles of a fluid which causes a liquid to offer resistance analogus to friction. An increase in the temperature usually reduces the viscosity; conversely, a temperature reduction usually increases the viscosity. Pipe friction loss increases as viscosity increases

The volute of a centrifugal pump is the casing that receives the fluid being pumped by the impeller, slowing down the fluid’s rate of flow. A volute is a curved funnel that increases in area as it approaches the discharge port. The volute converts kinetic energy into pressure by reducing speed while increasing pressure, helping to balance the hydraulic pressure on the shaft of the pump.



Water hammer
Occurs in a closed piping system as a result of the pressure being rapidly increased when the liquid velocity is suddenly increased. This damaging effect is usually the result of sudden starting, stopping, change in pump speed, or the sudden opening or closing of a valve. Water hammer can usually be controlled by regulating the valve closure time, surge chambers, relief valves or other means.

Wet end
The part of the pump that gets wet from the pumping fluid. Includes the volute, stuffing box, impeller wear rings, and shaft or sleeve.

Wilo Pumps
WILO is one of the leading manufacturers of pumps and pump systems for heating, cooling and air-conditioning technology and for water supply and sewage disposal. The company was founded in 1872 by Louis Opländer as a copper and brass goods factory and is now represented in more than 70 countries and employs about 6,000 personnel throughout the world.



Yield point
Where the metal passes from the elastic to the plastic range.



Zoeller Pumps
Zoeller Company began in 1939 as a family owned operation making various products, one of which was a dependable column sump pump.