Hach DR/700 Procedures Manual page 49

3. Press down on the turret cap with the thumb, using a smooth motion,
until the turret reaches the stop. Immerse the tip about 5 mm (¼") below
the surface of the solution to avoid drawing air into the tip. 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 to
the extended position. Do not let the turret snap into place, or the
delivery volume may be affected.
5. With the turret up, withdraw the tip from the liquid and move it to
the receiving vessel. Avoid placing pressure on the cap while moving
the pipet.
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