Separating Funnel

Pear Shape, Type 2, Glass Key
Pear Shape, Type 2, PTFE Key
Conical, Type 1, Glass Key
Conical, Type 1, PTFE Key

The links above show our list range of separating funnels which can be bought online. We can manufacture any other size to order, up to 10 litres. Please send an enquiry stating the size and style required and we will reply, usually within 24 hours, with a quote. Custom items normally take 1-2 weeks to manufacture.

Usage Guide

Separating Funnels are used to separate a mixture of two immiscible liquids. The mixture is poured into the funnel and allowed to settle until the two phases are fully distinct, one above the other. The stopper is removed and the lower phase is drawn off first through the stopcock.

Generally pear and conical separating funnels can be used interchangeably, but there are a few occasions when one is better than the other:

Pear shaped separating funnels are used when the solvents mixed are slow to separate, either because they are of similar specific gravity or because they form an emulsion. The greater surface area and smaller depth reduce the settling time.

Conical shaped separating funnels are useful when the solvents mixed are dark in colour. The narrower width makes seeing the interface easier.

Glass keys are the traditional type, now mostly superseded by PTFE. Some users prefer the glass type because they are harder wearing and easier to control. The main drawbacks are that they can jam if left in place, and the silicone grease used to lubricate them can contaminate the sample.