Hach DR/850, Procedures Manual, Page: 28 / 460

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CHEMICAL ANALYSIS INFORMATION
, continued
Using the TenSette Pipet
For best results use a new tip each time you pipet. After several uses, the
pipet tip may retain some liquid, causing inaccurate delivery. Each pipet
is supplied with 50 tips; order Hach replacement tips for best results.
Always use careful, even hand movements for best reproducibility. If the
pipet does not operate smoothly, disassemble and coat the piston and
retainer with high-quality stopcock grease. Also coat the metering turret
lightly with grease. Refer to the TenSette Pipet manual.
For best pipetting accuracy, the solution and the room temperature should
be between 20-25 °C.
Never lay the pipet down with the liquid in the tip. Solution could leak
into the pipet and cause corrosion.
Operating the TenSette Pipet
1. Attach a clean tip by holding the pipet body in one hand and gently
pressing the large end of the pipet tip onto the tapered end of the
pipet. Be sure a good seal is obtained.
2. Turn the turret cap to align the desired volume with the mark on the
pipet body.
3. Using a smooth motion, press down on the turret cap until it reaches
the stop. Immerse the tip about 5 mm (¼ inch) below the solution
surface to avoid drawing air into the pipet. Do not insert the tip any
deeper or the delivery volume may be affected.
4. While maintaining a constant pressure, allow the turret to return
slowly to the extended position. A rapid return may affect the
delivery volume.
5. With the turret up, take the tip out of the solution and move it to the
receiving vessel. Do not press on the turret cap while moving the pipet.
STEP 3 STEP 4 STEP 5