Asepto Syringe Bulb, Rubber

Quick Answer: An Asepto syringe bulb is the rubber squeeze bulb that fits on the wide end of an Asepto-type bulb syringe, a glass or plastic barrel that tapers to a tip. Squeezing and releasing the bulb draws liquid into the barrel and pushes it out again.

How the Bulb and Barrel Work Together

An Asepto-type syringe has no plunger. The rubber bulb sits over the open top of the barrel, and the hand does all the work: squeeze the bulb, dip the tip into the liquid and relax the grip, and the bulb springs back, lowering the pressure inside so liquid rises into the barrel. A second squeeze sends it out as a controlled stream. Because the bulb is large and the barrel holds a useful volume, one stroke moves far more liquid than a dropper teat on a Pasteur pipette.

This listing is the replacement bulb. Bulbs wear out before barrels do: rubber slowly hardens, cracks around the neck where it is stretched over the barrel rim, or turns sticky with age. A new bulb restores the syringe’s suction. Before ordering, check that the bulb neck suits the rim diameter of the barrel in use, since a loose bulb leaks air and a tight one splits.

In laboratories the same action is used for rinsing precipitate from a beaker onto a filter, topping up liquid levels and transferring media or buffers. For patient irrigation, use a sterile syringe supplied for that purpose.

Specifications

Applications

• Replacing a worn or split bulb on an existing Asepto-type syringe
• Rinsing solids from a beaker onto filter paper during filtration
• Transferring larger volumes of buffer, media or water than a dropper allows
• Nursing skills training that uses bulb syringes

Care & Handling

• Stretch the bulb over the barrel rim gradually; do not force it, which tears the neck.
• Keep rubber away from oils, greases and organic solvents, which make it swell and weaken.
• Store bulbs in a cool, dark place, as sunlight and ozone crack rubber over time.
• Check the bulb’s rating before boiling or autoclaving it.

Why Choose LabEquip

Hospitals, nursing schools and laboratories keep spare bulbs so a barrel is not discarded when only the rubber has failed. LabEquip lists this bulb in the General Lab Products range; send your barrel size through the contact page so the right neck is supplied.

Frequently Asked Questions

What is an Asepto-type syringe?

It is a bulb syringe: a glass or plastic barrel that tapers to a tip, with a rubber bulb on the wide end instead of a plunger. Squeezing and releasing the bulb moves liquid in and out.

How do I know if the bulb will fit my syringe?

Measure the outside diameter of the rim at the top of your barrel and compare it with the neck of the bulb. Share that measurement when you enquire so a matching bulb is supplied.

Why has my old bulb stopped drawing liquid?

The rubber has usually lost its spring, or a crack near the neck is letting air in. Either way the bulb cannot create enough suction and should be replaced.

Can the bulb be used with solvents?

Rubber generally tolerates water and dilute aqueous solutions, but many organic solvents and oils make it swell or soften. Keep solvent work to glass pipettes with suitable fillers.

How should the bulb be cleaned?

Remove it from the barrel, wash inside and out with warm water and mild detergent, rinse well and let it dry with the neck facing down so water drains out.

Why does rubber crack in storage?

Oxygen, ozone, sunlight and heat slowly break down rubber, starting at stretched areas. Storing bulbs cool, dark and unstretched slows this ageing.

Last Updated: September 2026