In this image of a pipette, what do the double rings mean?

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1 Answer 1


The pipette is a "blow out" type, denoted by a set of two rings printed on the upper end, meaning that a rubber bulb should be used for blowing. If there are no rings on the upper end of the pipette, do not blow out the solution. A blow out pipette ensures precise transfer of the required volume by using a rubber bulb to remove the last bit of liquid from the tip.

The tip of a pipette that has one ring or no rings at all empties itself by gravity.

  • $\begingroup$ Both empty by gravity surface tension holds liquid in for the to-deliver pipet; the retained liquid is dispelled for the to-contain pipet. My question is how are the 2 lines used for the fill mark on the TC pipet $\endgroup$
    – jimchmst
    Commented May 9 at 22:02
  • 1
    $\begingroup$ It is not filled till the 2 lines. It has other volume markings. $\endgroup$
    – Siva
    Commented May 23 at 8:26

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