Graduated Burettes with PTFE Stopcock

A burette delivers an accurately measured, variable volume of liquid — its role in titration, where titrant is added drop by drop until a reaction reaches its endpoint. The long, finely graduated tube lets the analyst read the volume delivered to a fraction of a millilitre, and a stopcock at the base controls the flow precisely.

A PTFE stopcock is preferred over a ground-glass one because PTFE needs no grease (which could contaminate the titrant or seize), turns smoothly and resists almost all chemicals. Burettes are calibrated 'to deliver' (TD) the stated volume.

Acid-base, redox and complexometric titration, volumetric analysis and standardising solutions, in QC, analytical, pharma, food-testing, environmental and teaching labs. Class A burettes are used where titration results must be accurate and documented.

A long borosilicate 3.3 tube with a fine precision scale (for example 0.1 ml divisions on a 50 ml burette) and a PTFE straight-bore stopcock with a fine delivery tip. Class A burettes are made to tight tolerances and certified; they are calibrated to deliver (TD/EX) the indicated volume.

Fill and rinse with the titrant, expel air from below the stopcock, and read the meniscus at eye level. Adjust the PTFE key so it turns freely but seals; do not over-tighten. Do not heat a burette, as it changes calibration. Drain and clean after use, especially with reactive titrants, and keep the stopcock with its own burette.

Formed from borosilicate 3.3 tubing with a precision bore, fitted with a machined PTFE stopcock. The fine scale is applied after the burette is calibrated against reference standards; Class A units are certified. Bore uniformity (for even drop size) and calibration accuracy are the critical checks.