Factor	Electric	Air-Powered	Piston
1	Flow rates > 15 GPM
2	Pump lift > 250 ft.
3	Well diameter is under 3"
4	Short water column conditions
5	Viscosity greater than water
6	Explosive/flammable environment
7	Silt and solids present
8	Solvents being pumped
9	Corrosives being pumped
10	Pumped liquid temperatures over 140° F
11	Gases and foams present in liquid
12	Able to tolerate discharge line becoming clogged or plugged
13	Air contact created solids possible

Electric Complete electric pump system includes: Centrifugal pump, control box, well-level probes, wellhead cap, discharge piping, downwell power supply cable, electrical power supply. Electric centrifugal pumps use an electric motor to drive high-speed impellers (generally at rotational speeds of 3750 RPM) to provide flow. The impellers are usually supplied in multiples, called stages, to provide the desired combination of pump flow rate and discharge head. The motor chamber is usually filled with water or oil for cooling purposes, but is sealed to protect the bearings and motor from the well environment. Electric submersible pumps are most commonly available in approximately 3.625 in. diameter, to fit inside 4 in. wells, although a few specialty models are made to fit inside 2 in. and 3 in. diameter wells. In all cases, the pump inlet is above the motor, at the bottom of the pump section. The power supply switch and low-liquid level shut-off controls are housed in a control box. The level control system also requires down-well probes to sense liquid level. A complete electric pump system includes the pump, power supply to the well, control box, well level probes, wellhead assembly, discharge piping and power cable. All of these components need to be considered in the specification, installation and operation phases. The pump system specification process begins with identifying the required pump performance in terms of flow rate and discharge head, and then finding the pump performance curve that best fits the application. Then the controls, power supply and cables are selected. However, it is important to research and adhere to all of the motor and pump application limits, such as related to temperature, cooling flow pat the motor, liquid viscosity, solvents and solids.

Air Powered Complete air-powered automatic pump system includes: Pump, tubing or hose for liquid discharge, air supply and vent, wellhead cap, air supply. Automatic air-powered pumps use an internal float mechanism to activate an air valve inside the pump. The air valve alternately pressurizes and exhausts the pump cavity to drive fluid out, then refill using hydrostatic pressure. Air-powered automatic pumps (APAs) are available in a range of diameters, lengths, top and bottom inlets and materials. With air-powered pumping systems, air lines are run to the pump instead of electricity, providing immediate benefits in simplicity and safety. Pumps are delivered as a complete system, including the necessary tubing, connectors and custom wellhead flange or cap closures. A recommended option is an air filter/regulator. The complete system's lightweight and compact size speeds installation and generally requires only one person. An compressed air source also is needed to power the pumps. The pump system specification process begins with identifying the required pump performance in terms of flow rate and discharge head, then selecting an air-powered pump model with a maximum flow rate that meets the requirement. Note that air-powered pumps can operate without adverse effects at any flow less than maximum, and always have full discharge head available at all flow rates. The variety of sizes, materials and inlet arrangements available for air-powered pumps allows for specific pump-to-application matching.

Piston Complete piston pump system includes: Pump driver at wellhead, downwell pump assembly with piston and cylinder, piston drive rod connecting driver to piston, drop pipe which connects wellhead to pump cylinder down well, level control, air supply. Down-well piston pumps such as farmyard hand pumps, windmill pumps and oil field sucker rod pumps all function basically the same: a piston is raised and lowered in the pump cylinder, lifting fluid above and below the piston. On the lift stroke, the liquid above the piston is raised toward the well head. Each lift stroke also applies suction to the pump inlet below the piston, drawing more liquid into the pump cylinder for the next stroke. On the piston down stroke the piston does no work as the liquid just passes through the piston's check valve as the piston heads downward. A piston pump system is a simple technology using an assembly of several components. The piston is connected to a drive rod, which is connected to a reciprocating driver at the wellhead. Drivers can be air-powered, electric or even windmill powered. For air-powered piston pumps, a compressor is required along with air supply tubing to the driver and discharge tubing or hose from the well head. Pump activation and liquid level are often controlled by air bubbler system. Timers may be used where well conditions interfere with reliable performance of level control devices. The pump system specification process begins with identifying the required pump performance in terms of flow rate and discharge head, then selecting a piston pump model with a maximum flow rate that meets the requirement. Note that piston pumps can operate without adverse effects at any flow less than maximum, and have full discharge head available at all flow rates. Piston pumps offer the unique ability to operate in slant or horizontal wells and pump viscous and high temperature fluids.

Applications
Electric Designed primarily for moving high volumes of cool, clear water. Standard pumps fit small residential wells of 4" or more in diameter, specialty models fit wells 2' and larger. Pumps from depths of up to 600 ft. Can have limited application where there is work site explosion potential. Can function in horizontal or slant wells.	Air Powered Designed specifically to pump not only clear water but difficult fluids (materials with explosion potential, corrosive liquids, solids, solvents and viscous fluids). Requires the well to be vertical. Fits 2" wells and larger. Pumps from depths of up to 250 ft. in standard models, and 300 ft. with the 2" well pump. Depths over 200 ft. require air supply over 100 psi.	Piston Designed specifically to pump difficult fluids (materials with explosion potential, corrosive liquids, solids, solvents and viscous fluids). Can be used in slant and horizontal wells. Fits 4" wells and larger. Capable of pumping from depths beyond 400 ft.
Flow/Pressure Output
Electric Designed to operate at limited combinations of discharge head and flow rate as defined by the manufacturer's flow curve. Variations from their designed flow curve require sophisticated variable-speed control mechanism. If the pump is not equipped with a variable-speed control, well condition variations can lead to cavitation, impeller erosion and overheating. Excessive start/stop cycles cause overheating, which first affects performance and eventually leads to pump burn out.	Air Powered Any flow rate from zero to maximum is available without affecting pump life, and full discharge head is maintained. Air flow adjustments are simply made at the wellhead to control liquid flow. Air-powered design makes pump overheating impossible. Frequent start-stop cycles have no negative impact on pump mechanism or longevity.	Piston Any flow rate from zero to maximum is available without affecting pump life, and full discharge head is maintained. Air flow adjustments are simply made at the wellhead to control liquid flow. Wellhead driver avoids potential for pump overheating. Frequent start-stop cycles have no impact on pump mechanism or longevity.
Durability
Electric The fundamental electric submersible pump was developed for pumping clear, cool water, so durability in harsh conditions is highly variable. Overheating and wear of high speed components are predominant problems that limit electric submersible pump's service life. In the presence of difficult fluids with corrosives, solids or solvents or high temperatures, pump life is greatly reduced. Typical warranty term is for only 1 year and only covers operation in a limited range of fluid conditions.	Air Powered Twenty years of specialty design and site experience have been invested specifically to provide long-term reliability and durability under extreme well conditions. Fluid-lifting work is performed by fluid-on-fluid pressure and there are no high-speed components, so long-term durability is enhanced. Commonly backed up by multi-year warranties that apply to severe applications.	Piston Oil field type "seal-less" design pistons have extended durability in harsh conditions of temperature, solids and viscosity. Simple, low-speed components minimize wear mechanical complications. Typically carry a one-year warranty on all components.
Mechanical Issues
Electric Abrasives or corrosives entering the motor typically translate into motor winding and/or motor bearing damage. Overloading the motor for long periods of time will effectively shorten its life span. High ambient temperatures can cause motor breakdown due to overheating. Electric pump motors have many failure modes, including overheating, locked rotor, power spikes including from lightning, seal and bearing wearout, and over-current draw. Voltage drops in the pump's power supply line can cause overheating and possible motor burn out. Down well level controls can become coated or corrode and require replacement.	Air Powered Pumps can be made of a variety of materials that can withstand harsh environments, thereby prohibiting wear. The simplicity of its mechanical design make air-powered pump far less prone to mechanical problems. Air-powered pumps cannot overheat. They have no motors or electronic parts. Solids and thick liquids pass safely through. Blockages rarely occur and if they do, the pump is easy to clean. Changes in air supply pressure and flow do not damage the pump. Does not require level controls.	Piston Pumps can be made of a variety of materials that can withstand harsh environments, thereby prohibiting wear. The simplicity of its mechanical design make air-powered pump far less prone to mechanical problems. Air-powered pumps cannot overheat. They have no motors or electronic parts. Solids and thick liquids pass safely through. Blockages rarely occur and if they do, the pump is easy to clean. Changes in air flow have no affect on pump life. Requires level control, typically a bubbler system.
Servicing
Electric Warranty terms are one year or less. Pumps can be cleaned out, but they cannot be rebuilt, which means they must be replaced. Additional cost incurred in servicing level controls. Has more components to service compared to APAs. Safety and liability concerns dictate that installation and service be performed by highly qualified personnel.	Air Powered Typical warranty terms are two to five years. If the pump becomes filled with solids, it is extremely easy to clean out the blockage and put the pump back to immediate service. Flow level control is inherent by design, therefore no controls are needed. Fewer and simpler parts to service, when service is needed. Compressor maintenance usually entails regularly checking the compressor intake filters and oil levels.	Piston Typical warranty terms are for one year. Pump driver located at wellhead eases many service steps. Drive rod and piston are light weight and easily removed by one person. Major components designed for ease of service rather than requiring replacement. Compressor maintenance usually entails regularly checking the compressor oil levels.

Materials
Electric Available in a limited range of materials intended primarily for potable water service. Stainless steel a common material for some components, but the grades of stainless steel and other materials used on different components on the same pump can vary considerably. Welds and wire connection terminals can be weak links. The presence of low pH, elevated temperatures, high salinity and dissolved solids can quickly corrode any metals below 304 or 316 SS grade. Elastomeric materials in the motor seals can be attacked by solvents.	Air Powered Manufacturers offer a wide range of construction materials to meet site-specific conditions (stainless steel, acetal, nylon, Teflon, brass, epoxy, fiberglass and UHMW). Broad material choices support higher operating temperatures and corrosion resistance.	Piston Manufacturers offer a wide range of construction materials to meet site-specific conditions (stainless steel, CPVC, epoxy). Broad material choices support higher operating temperatures and corrosion resistance. Elastomeric seals in the downwell piston on some designs and in the shaft seal at the surface can be attacked by solvents.
Emulsification of Free-Phase Liquids
Electric Pump's high-speed impellers create very fine water/hydrocarbon emulsifications that can be very difficult to remove in downstream treatment equipment such as oil/water separators, air strippers and activated carbon beds. Oil/water separators are commonly designed and sized on the basis of the desired removal efficiency for the smallest, most difficult to remove free-phase droplet sizes (e.g. 20 microns). Pump fluid shearing action actually creates these very small droplets, in effect substantially increasing the oil/water separator's required size.	Air Powered Fluid-to-fluid, low-speed component operating principle gently moves fluids through the pump and discharge lines without causing significant emulsification.	Piston Liquid handling is relatively gentle, causing minimal emulsification of the fluid.
Solids
Electric Presence of silt and sand excess can damage the motor shaft and seals, subsequently entering the motor, damaging the bearings, increasing friction and destroying the motor. Increased friction, in turn, causes the motor to draw more current and overheat, which leads to premature failure. Particulate matter most commonly causes rapid erosion of the high speed pump impellers, causing pump flow and pressure output to decrease accordingly. Large solid particles can cause the pump to lock up by jamming between the impeller and the cup, which usually destroys the motor.	Air Powered High-clearance inlet check valve allows solids and abrasive to flow cleanly through the pump. Pump design supports clean flow and, as well, allows no place for abrasions to settle. No motor to be impacted by solids or abrasives.	Piston Large clearance inlet and piston check valves allow solids and abrasives to flow cleanly through the pump. Seal-less designed pistons are not severely impacted by abrasives. Channels cut around the circumference of the piston trap larger particles, then allow them to tumble and break down until they can pass by the close tolerance side wall. No motor to be impacted by solids or abrasives.
Temperature
Electric Model-specific upper temperature limits are largely governed by seal materials and motor limits. A typical upper limit of high temperature models is 140° F. Pumps submersed in a warm fluid close to its specified temperature limits will also be more susceptible to the heat effects of stop/start cycling and lower flow rates due to throttling.	Air Powered Temperature does not affect mechanical operations. Broad material choices allow the pump to be built to highest temperature specifications.	Piston Temperature does not affect mechanical operations. Broad material choices allow the pump to be built to highest temperature specifications.
Air Contact Related Deposits
Electric Electric submersible pumps do not introduce air into the pumped fluid, so their use should not add to solids deposition at sites susceptible to this phenomenon, an advantage. However, if air contact has already initiated solids deposition and encrustation conditions in a landfill underdrain system, these solids may continue to deposit within the pump and lead to damage as described in the Solids section above. It should also be noted that high pumping rates are felt by some researchers to aggravate solids encrustation conditions in landfill underdrain systems.	Air Powered Air-powered automatic pumps introduce direct contact of the drive air with the pumped fluid, which can initiate or exacerbate solids deposition at sites prone to this phenomenon. Although risers with this condition are rare, when it does occur it can be troublesome and costly to service. The deposits can restrict or block the pump discharge tubing and downstream collection piping, and be very difficult or impossible to remove.	Piston Piston pumps do not introduce air into the pumped fluid, so their use should not add to solids deposition at sites susceptible to this phenomenon, an advantage. However, if air contact has already initiated solids deposition and encrustation conditions in a landfill underdrain system, these solids may continue to deposit within the pump and lead to piston seizing as described in the Solids section above. Also, for sites with air-induced solids depostion tendencies, bubbler type on/off level control systems shoud not be used to control the piston pump.

Controls
Electric Systems require a control box, governed by well float switches or level probes. A short or spark in the control box can cause explosions where volatile materials are pumped. Building a system to full explosion-proof standards raises costs markedly. The system is vulnerable to failure due to lightning strikes, power surges, moisture, and deposits that can form on the level sensing probes. If the level sensing system malfunctions for any reason, the pump will likely suffer catastrophic failure due to motor overheating caused by the well running dry. Additional control components can be added to reduce risk, but this will raise the costs, complexity and control box size. Some sites pose a challenge to simply find a safe and suitable place to mount the controls.	Air Powered Requires no control boxes due to its inherent design. With no control box, presents no explosion potential. No electricity is used at the pump site, eliminating explosion vulnerabilities.	Piston Flow can be controlled by a simple air valve adjustment. A simple bubbler system with control box is used to activate the pump at specified levels.

Installation
Electric Installation and start up requires a certified electrician. Must meet stringent codes for explosion protection. Requires a crew to handle the pump due to its weight.	Air Powered In general, installation, start-up and maintenance procedures are relatively easy to perform and require no special technical training beyond the basics. Air-powered pump installation does not fall under the strict electrical codes.	Piston Installation of a piston although fairly simple, requires close attention to measurement of the drive rod length and allowance for time and labor to install the drop pipe. Installation into a slant or horizontal well may present additional issues with the drop pipe laying on the well casing.
Diameter
Electric Pumps used for remediation are at least 3.875 in. (9.84 cm) in diameter, which limits their use on existing, smaller wells. Some smaller pump sizes are available in specialty versions, but these are limited, more expensive and usually require sophisticated variable frequency controllers.	Air Powered Some pump models are designed to fit into wells as small as 2 in. (5.08 cm) in diameter. Can be used either in existing small wells or in special site conditions.	Piston The diameter of the drop pipe couplings limits its use to 4" wells or larger.
Power Source Considerations
Electric Power supply lines, control boxes and the pumps need to meet specific safety codes, and consequently, the site or pumping application may restrict or prohibit electric pump use. Buried power lines can create a serious site hazard if heavy equipment is present or if digging, trenching or drilling take place. Electricity can be supplied from a utility or, at some landfills, from onsite methane-generated electricity.	Air Powered Compressors are generally electric-powered, but electric power is not run directly to the pump or to the well, therefore eliminating any safety concerns or code requirement. A single air-compressor can be specified to operate multiple pumps. Tubing size and length of runs impact the size of the compressor required. Electricity can be supplied from a utility or, at some landfills, from onsite methane-generated electricity.	Piston Compressors are generally electric-powered, but electric power is not run directly to the pump or to the well, therefore eliminating any safety concerns or electrical code requirement issues. A single air-compressor can be specified to operate multiple pumps. Tubing size and length of runs impact the size of the compressor required. Electricity can be supplied from a utility or, at some landfills, from onsite methane-generated electricity.