Image Credits: U.S. Plastic Corporation and Small Parts, Inc.
Burettes are used for precisely dispensing liquids in laboratory experiments. Manual burettes (burets) are tall graduated tubes, with a tap or stopcock at the bottom. Digital burettes are electronic devices.
How Burettes Are Used
Burettes are used to measure the exact amount of liquid that has been dispensed, usually in a titration experiment.
This video explains how manual burettes are used.
Video Credit: Minnesota State University Moorhead
Use of a digital burette is presented in this video.
Video Credit: Brezinski Racing
Types of Burettes
ASTM details two specifications for manual glass burettes: Class A (precision grade) and Class B (general purpose grade). Manufacturers sometimes use these classifications for plastic burettes.
Digital or bottletop burettes are attached to containers and use microprocessors to measure the liquid that is disbursed.
Volume and materials of construction are important to consider when selecting burettes. In volume, manual burettes can range from 5 to 4,000 cc. In terms of materials, manual burette tubes are usually made from glass or plastic. Stopcocks are generally made from Teflon (PTFE). The nature of whatever liquid is being measured should be considered carefully when choosing a material.
Features and Applications
Manual burettes are marked by gradations-appropriate to the volume of the labware-to aid measurement. Stopcocks can feature one or two dispenser tubes, a push-button permitting drop-by-drop delivery, and a small screw clamp that presets drop speed.
Image Credit: Daigger & Company, Inc.
Self-zeroing, auto-fill, or automatic kits consist of a plastic bottle and/or rubber bulb that allows for more precise filling or safe handling of hazardous solutions.
Automatic with squeeze bottle
Automatic with bulb
Image Credit: Science Lab
Digital burettes can be powered manually (by hand cranking/spinning) or electronically (by batteries or solar panels). They can also feature LCD screens, light protection, recirculation systems, computer interfaces for data logging.