Glassware
Ground Glass Joints
Ground glass joints are used to attach pieces of glassware together. The two main types of ground glass joint in use are socket and cone, and ball and socket.
Socket and Cone
Socket and cone (conically tapered joints) allows the interconnection of different pieces of glassware, for example connecting a round bottom flask to a Liebig condenser when setting up a reflux apparatus. They consist of a cone which fits into a socket. The most common type have conically tapered joints, generally with a 1:10 taper (this means that for every 10 mm long the joint is there will a 1 mm difference in the widths at either end) and the cones and sockets come in a variety of sizes.
In teaching labs the main sizes we have are B14/23, B19/26, B24/29, B29/32, and B34/35. The B refers to a British standard, the first number is the diameter of the widest part of the cone or the widest part of the socket (in mm), and the second number is the length of the ground glass joint (in mm). However, these names are more commonly shortened, for example you may hear technicians referring to B19 round bottom flasks, meaning a round bottom flask with a B19/26 ground glass joint.
Ball and Socket
Ball and socket joints are comprised of an inner ball joint and an outer socket joint, held together using a joint clip. They enable joints to be made between glassware at different angles, they also allow for more flexibility within the joint. They are commonly found on rotary evaporators were the load on the joint increases as more solvent is collected in the flask, they are also found on Schlenk and gas lines particularly for connecting long lengths of glassware.
Joint clips are used to hold ball and socket joints together. They are commonly used to attach collection flasks to rotary evaporators and vacuum pumps.
Adapters
Expansion
Expansion adapters are used to connect smaller sockets to larger cones. They are most commonly used for connecting a round bottom flask to the rotary evaporator. They are given name codes based on the joint sizes and always prefixed with 'XA' with numbers indicating the joint sizes from the top of the adapter to the bottom. For example, XA43 would connect a round bottom flask with a neck size of B24 to a rotary evaporator with a joint size of B29. The table below gives more information about the relationship between joint size and adapter name.
Reduction
Reduction adapters are used to connect larger sockets to smaller cones. They are most commonly used for connecting condensers to large round bottom flasks. They are given name codes based on the joint sizes and always prefixed with 'DA' with numbers indicating the joint sizes from the top of the adapter to the bottom. For example, DA34 would connect a round bottom flask with a neck size of B29 to a rotary evaporator with a joint size of B24. The table below gives more information about the relationship between joint size and adapter name.
Thermometer (screw thread)
Thermometer (screw thread) adapters are used to fix a thermometer into the vessel while keeping it sealed. They come in a variety of cone sizes, have a rubber seal which fits around the thermometer, and a plastic screw top which ensures a tight fit.
Right Angle
Right angle adapters are mostly used for connecting vacuum lines or for attaching bellows at the top of a flash column.
Keck Clips
Named after the German chemist Hermann Keck, these simple clips were patented in 1984 (US4442572). The clips are designed to secure cones into sockets to prevent glassware coming apart. They are available from B10 through to B45 and are colour-coded for simplicity.
The table below shows the main socket and cone joint sizes, with the corresponding keck clip colours and adaptor codes.
Joint Size
Keck Clip Colour
Adapter Code
B10
Green
0
B14
Yellow
1
B19
Blue
2
B24
Green
3
B29
Red
4
B34
Orange
5
B40
Yellow
6
B45
Brown
7
B50
-
8
B60
-
9