| Use: | Peristaltic pumps are frequently used for shallow ground water sampling. Surface centrifugal pumps are commonly used for well development. |
Description:
Suction-lift pumps apply a vacuum to either the well casing or to tubing that runs from the pump to the desired sampling depth. Most are easily controlled to provide continuous and variable flow rate. Peristaltic pumps utilize a self-priming or power-operated vacuum pump.
A centrifugal pump, in its simplest form, consists of an impeller rotating inside a casing. When liquid is in the housing, the rotors spin it to create centrifugal force to drive it toward the walls and the outlet. Liquid enters along the axis to replace the liquid that spins away. The impeller imparts kinetic energy to the fluid. The amount of energy given to the liquid corresponds to the velocity at the edge of the impeller. The faster the impeller revolves or the bigger the impeller is, the higher the velocity of the liquid at the edge of the impeller and the greater the energy imparted to the liquid. The kinetic energy of a liquid coming out of an impeller is harnessed by creating a resistance to the flow. The first resistance is created by the pump volute (casing) which catches the liquid and slows it down. The velocity head (for non-viscous liquids like water or gasoline (newtonian fluids), the term "head" is used to measure the kinetic energy which a pump creates), which is created by moving fluid from the low-velocity center to the high-velocity edge of the impeller, is converted into a pressure head (pressure is a measurement of the resistance to flow; a pump does not create pressure, it only creates flow) when the fluid leaves the pump.
Analytes:
| 1. Non-Halogenated VOCs | 5. PAHs | 9. Inorganics |
| 2. Non-Halogenated SVOCs | 6. Pesticides/Herbicides | 10. Explosives |
| 3. Halogenated VOCs | 7. Metals | 11. TPHs |
| 4. Halogenated SVOCs | 8. Radionuclides |
Ground water samples containing VOCs require the use of sample tubing and containers that can be used in combination with gas headspace / vacuum extraction, purge and trap extraction, or adsorption/thermal desorption samplers.
Media:
| Soil: | Ground Water: | Surface Water: | Gas/Air: |
| Not Applicable | MINIMUM | MINIMUM | Not Applicable |
Sample does not come into contact requiring that only tubing be cleaned. However, the drop in pressure caused by the suction causes degassing of the sample and the loss of volatiles especially if the sample is taken from an in-line vacuum flask. The gasoline power source used for most pumps causes aeration and turbidity which may disturb sample integrity. Centrifugal pumps may have to be primed.
| Maximum Depth: | Up to 25 feet. Maximum sample depth: 25 feet (peristaltic) to 15 feet (surface centrifugal). Minimum well diameter: 0.5 inch (peristaltic) to 1 inch (surface centrifugal). |
| Production Rate: | Sample is available after a short amount of time. 0.01 to 8 gallons per minute (peristaltic) to 1 to 25 gallons per minute (surface centrifugal). |
| Investigation Derived Waste Volume: | Medium volume of waste. |
| Technology Status: | Commercially available and routinely used field technology. |
| Certification/Verification: | Technology has not participated in CalEPA certification and/or CSCT verification program. |
| Relative Cost per Sample: | Least expensive. |
Limitations:
ASTM Standards:
| D 6232 | Standard Guide for Selection of Sampling Equipment for Waste and Contaminated Media Data Collection Activities. |
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