TM 10-6630-245-13&P2.6.1.7. UsingPipets.Pipets are used to accurately measure a volume of liquid and then to transfer it to a vial or other container. There aretwo general types of pipets in the WQAS-PM: dropping pipets and standard volumetric pipets (including one micropipet).a.Dropping Pipets.(1)Use: Dropping pipets are found in several of the individually packaged test kits within the WQAS-PM.They are simply eyedroppers with a liquid-level line marked on them. They are used to measure andtransfer liquid when only a reasonable amount of accuracy is necessary. They are also used to addreagents to a solution drop by drop (titrating).(2)Drop Size: The size of a drop from a dropping pipet may vary depending on how the dropper is held. Foraccurate results with the WQAS-PM drops should be kept the same size. Two things are most important inproducing drops of the same size.(a)The angle at which the dropper is held: The dropper should be held vertically, that is straight up anddown, when expelling drops.(b)How hard the rubber bulb is squeezed: The rubber bulb should be squeezed firmly, slowly, andsteadily, until a drop is formed at the tip and falls into the container. Some practice is required to beable to consistently produce drops of the same size.b.Standard Volumetric Pipets: Volumetric pipets are used to measure and transfer liquids when great accuracy isneeded. There are three volumetric pipets in the WQAS-PM. They are found in the main carrying case. Use of all threeis similar.(1)Rinse: Rinse the pipet two or three times with the sample to be tested before filling. Always use a pipetfiller to draw the sample into the pipet (fig. 24).WARNINGNever pipet chemical solutions or water samples by mouth. May be harmful if swallowed. Usethe pipet filler. In the event a reagent is accidentally swallowed, follow the directions in thewarning statement for that reagent.(2)Fill: Fill the pipet(l) using the pipet filler(2). The pipet filler is a rubber bulb with several valves. It is usedto draw liquid into the pipet and to expel the liquid into a container. It is used as follows:Figure 2-4. Using the Pipet Filler.(a)Insert the pipet(l) into the tube on the pipet filler(2) containing Valve S(3) until it is firmly seated. Ifnecessary use a twisting motion to firmly seat the pipet(l) within the tube.(b)Squeeze Valve A(4) while squeezing the rubber bulb. Lower the tip of the pipet(l) into the liquid.2-15
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