Pipette Bulb

Quick Answer: The Pipette Bulb is a plain rubber suction bulb that fits over the top of a glass pipette. Squeezing it, fitting it and then letting go draws liquid up the pipette, replacing mouth pipetting for simple transfers.

Simple Suction and Its Limits

A plain bulb has no valves. The user squeezes out the air, presses the open end onto the pipette, and lets the rubber recover to pull liquid up. To set the meniscus on a mark, the bulb is lifted off and a dry fingertip is placed over the top of the pipette, then eased slightly to let the level fall. That makes it quick for rough transfers, but setting a level accurately depends on the user’s technique.

The bulb’s own volume limits how far it can lift liquid in one squeeze. A small bulb may not raise liquid above the mark of a large volumetric pipette, so bigger pipettes need a bigger bulb or a filler. Bulbs come in several sizes, and the right one covers the pipette top snugly without being forced.

For measured volumes, many labs prefer the three-valve pipette filler, which holds and releases liquid through its valves without removing the bulb. At the small end of the range, dropper-size rubber teats serve Pasteur pipettes and droppers.

Specifications

Care & Handling

• Squeeze out the air before fitting the bulb, never after, or liquid can be blown out of the pipette.
• Hold the pipette upright and do not let liquid rise into the rubber.
• Rinse and dry the bulb after reagents such as acids or ammonia touch it.
• Replace bulbs that are slow to recover their shape or have cracked at the neck.

Applications

• Drawing up approximate volumes of reagent with a graduated or dropping pipette
• Filling bulb-type glass pipettes in class practicals
• Taking off the clear liquid above a settled precipitate
• Rinsing a pipette with the solution it is about to measure

Why Choose LabEquip

Plain bulbs are a practical choice for schools where most pipetting is approximate, and as spares beside each sink. LabEquip lists them in the General Lab Products range; share your pipette sizes on the contact page.

Frequently Asked Questions

What is the difference between a pipette bulb and a pipette filler?

A plain bulb only provides suction; the level is set by removing it and using a fingertip. A valve filler has built-in valves to draw up, hold and release liquid while staying attached, which gives more control.

Can I set an exact volume with a plain bulb?

Yes, with practice. Draw the liquid above the mark, remove the bulb, cover the top with a dry fingertip and ease the pressure until the meniscus sits on the line. A valve filler or pump makes this easier for beginners.

Why won’t the liquid rise high enough?

Either the bulb does not seal on the pipette top or its volume is too small for the pipette. Try a snugger fit, or use a larger bulb or a valve filler for bigger pipettes.

Is a pipette bulb the same as a teat?

They work the same way, but a teat is smaller and fits droppers and Pasteur pipettes, often staying on permanently. A pipette bulb is larger and is taken on and off volumetric or graduated pipettes.

How do I clean a pipette bulb?

Squeeze warm water in and out several times, then squeeze it dry and leave it neck-down to drain. Avoid solvents and strong oxidisers, which damage rubber.

Why is mouth pipetting unsafe?

Liquid can reach the mouth by accident, and vapours from acids, ammonia or solvents are inhaled even when it does not. Schools and colleges ban the practice for these reasons, and a bulb removes the need for it.

Last Updated: September 2026