A volumetric pipette is either a TD or a TC pipette. The abbreviations TD and TC are printed on the pipette. A TD pipette is calibrated to leave a small amount of liquid in the tip. The TD type of pipette is calibrated to leave the smallest amount of liquid in the tip.
The tip of a TD or T.C pipette is a rounded-end, hollow-tip device that contains the liquid. The tip of the TC or TD pipette is unpacked from the upper end, immersed in the liquid, and the aspirated liquid is dispensed from the pipette. The TD is held at eye level, allowing the user to observe the dispensed volume from the smallest to the largest tip.
In serology, the TD pipette is calibrated to contain or deliver liquid. The to-deliver TD pipette is marked with a double ring near the top. The smallest part of the td must be blown out with the pressure from the pipette bulb. A TC tip should be held at eye level in order to avoid accidental blowout.
If the TD tip is calibrated to deliver, it is not necessary to blow out the small amount of liquid inside. The TD pipette is a versatile device, and the last milliliter must be discarded properly. The to-deliver td has a double ring near the top. While the to-contains td must be blown out with the pressure of the pipette bulb, the td must contain.
When using a TD pipette, make sure that you understand the difference between a to-deliver and a to-contain td. The former is calibrated to contain the liquid, while the latter is calibrated to deliver the liquid. The TD tip is the to-deliver one. Touch it to the side of the flask to get rid of any clinging drops.
TC pipettes are used to deliver liquid, while TDs are designed to contain the liquid. The TC pipette is used to dispense a small volume of liquid. The TC is more convenient and is often used to measure a larger volume of fluid. If you have a TD, the second is for a sample delivery.
TD and TC pipettes are similar in use, except that the TC pipette contains the liquid. Using a TD, you insert the pipette tip into the liquid and dispense it. The TC is more frequently used than the TD. Both types are calibrated to contain the liquid. Neither type has a pre-set metric.
A TD pipette should not be used for delivering small amounts of liquid. A TD pipette should be blown out with air, while a TC pipette is used for delivering large volumes of liquid. Both types require that you hold the pipette at eye level and press down on the bulb. The TD and TC tip are designed for different applications. For example, the TC tip should be kept at eye level and the corresponding size for a large volume of liquid.
To deliver liquid from a T.D. pipette, it is important to ensure that the pipette has a tip that has a double ring near the top. The TD pipette should be blown out with air to ensure that the liquid is delivered correctly. Afterwards, it should be blown out with air, so as not to lose the clinging drop.