US Standard Size Joint Will Fit into European Standard Size Joint
Standard Taper Ground Glass Joints are interchangable.For either frosted, presicon-ground standard taper joints (same size),the inner ground surfaces (male joint) make a good seal with the outer(female joint)). The joint size is described by the form A/B. The first number A represents the outer diameter (OD) in millimeters (mm) at the widest point of the inner (male) joint and the second number B represents the length of the joint. For example, a 14/20 joint is 14 mm wide at the top (the widest part) and is 20 mm in longth. The joint has a standard taper 1:10, any two joints (male and female) with the same outside diameter (A)can fit into each other ,no matther how lenght the joints are. For example, a 24/40 (US standard size) joint on a condenser will fit into a 24/29 (European standard size)flask but the ground glass joint will protrude (40 - 29) 11mm into the flask.
Taper-Ground Joints
Joint Size Number Designation | Approximate Diameter at Small End(mm) | Approximate Length of Ground Zone(mm) | Diameter of large End of Ground Zone(mm) |
10/18 |
8.2 |
18 |
10 |
10/30 |
7 |
30 |
10.0 |
14/20 |
12.5 |
20 |
14.5 |
19/22 |
16.6 |
22 |
18.8 |
24/40 |
20 |
40 |
24.0 |
29/42 |
25 |
42 |
29.2 |
34/45 |
30 |
45 |
34.5 |
40/50 |
35 |
50 |
40.0 |
45/50 |
40 |
50 |
45.0 |
50/50 |
45 |
50 |
50.0 |
55/50 |
50 |
50 |
55.0 |
Spherical Ground Joints
Joint Size Number Designation | Nominal Diameter of Ball(mm) | Nominal Tube Inside Diameter(mm) |
35/20 | 35 | 20 |