BS 2021:1980 pdf download.Separating and dropping funnels for laboratory use.
Separating funnels are mainly used in laboratories for liquid extractions, and they are intended to facilitate the separation into layers of two immiscible liquids of different density.
The stem of a separating funnel should be short and must be reasonably wide in order to avoid the formation of a liquid column, which could lead to unsatisfactory separation.
Dropping funnels have a cylindrical body and are used for adding reagent solutions to a reaction vessel. They are, therefore, often provided with a ground cone at the bottom, for joining to vessels with conical ground necks.
Some confusion has been caused in the past by incorrect references to a pear-shaped funnel as a “dropping funnel and a cylindrical funnel as a separating funnel
1 Scope and field of application
BS 2021 specifies details of an internationally acceptable series of glass separating
funnels and dropping funnels suitable for general use in laboratories.
2 References
5.3.1 The graduation marks may be figured (see 7.5.1)
— in ascending order, or
— in both ascending and descending order (see 7.5.3).
5.3.2 Scales may be provided with a longitudinal reference line through the midpoint of the graduation lines to facilitate reading if the funnel is in an inclined position.
NOTE The scales of graduated dropping funnels only indicate approximately the volumes of liquid contained.
6 Inscriptions
The following inscriptions shall be permanently marked on all separating funnels and dropping funnels:
the nominal capacity, except for graduated dropping funnels;
— the symbol cm3 or the symbol ml;
— the maker’s or vendor’s name or mark.
7.5 Type 5— Graduated cylindrical dropping funnels
Dimensions as shown in 7.4.
7.5.1 Graduation
BS 2021 was first published in 1953 under the direction of the Laboratory Apparatus Standards Committee. It was revised in 1961 and has now been again revised in a form identical with ISO 4800:1977 “Laboratory glassware — Separating funnels and dropping funnels”, prepared by Technical Committee 48, Laboratory glassware and related apparatus, of the International Organization for Standardization (ISO).
The 1961 edition of BS 2021 is now withdrawn. The main changes from the 1961 edition are as follows.
a) Five types of funnel are now specified in place of six types. Type 1 corresponds to the former type 2B.
Type 2 corresponds to the former type 1 B, but is now described more accurately as “pear-shaped” rather than “spherical”.
Type 3 is specified for the first time.
Type 4 corresponds to the former type 3.
Type 5 corresponds to the former type 4.
The former tvoes 1A and 2A. with a short lernrth of tube between the bulb.BS-2021-1980