Laserfiche WebLink
Advantages <br />Disadvantages <br />Easy to decontaminate. <br />Labor intensive. <br />Inexpensive. <br />Difficult to sample from a set depth. <br />Portable <br />Creates turbidity. <br />Table 7. Inertia Pump Advantages and Disadvantages <br />B.6.8. Positive -Displacement Mechanisms <br />Positive -displacement mechanisms consist of gas -driven devices and gas -operated bladder <br />pumps. NS currently uses nitrogen gas. These devices are generally used to sample <br />groundwater when the liquid must be pumped to the surface. Positive -displacement devices <br />can be constructed of a variety of materials to fit most sampling situations. Table 8 and Table 9 <br />present the advantages and disadvantages of positive -displacement mechanisms. <br />Advantages <br />Disadvantages <br />Device can be used in wells with <br />inside diameter as small as 2.0 inches. <br />Oxidation and gas -stripping of volatiles may <br />occur if air or oxygen is used as the driving gas. <br />Device is inexpensive and highly <br />portable for most sampling <br />applications. <br />Requires compressor or large compressed -air <br />tanks. Application of excessive pressure can <br />rupture the gas entry or discharge tubing. <br />Permanent installation is possible in <br />boreholes without casing. <br />Difficult to retrieve for repair, cleaning, and <br />maintenance when installed permanently in <br />boreholes without casing. <br />Inert materials can be used for <br />construction of device. Sample <br />delivery rate can be controlled. <br />Burst strength of the materials used <br />to make device and tubing is only <br />limiting factor in determining <br />sampling depth. <br />Daub & Associates, Inc. <br />Table 8. Gas -Driven Device Advantages and Disadvantages <br />Page B-16 Natural Soda LLC 2015 S A P <br />