About threads

About threads – how to determine thread sizes

Plastic barrels and containers can have a wide range of thread types. Some are standardized according to DIN, BSI or US standards. Other threads are manufacturer- specific. We can supply suitable adapters for most containers so that discharge valves, pumps and other accessories can be safely attached. Various steps are necessary in order to select the correct adapter. Proceed as follows:

  1. First use the thread table to select the container thread. If possible use calipers for the measurement, although most threads can be measured accurately enough with a ruler. If your container has an outer thread you will require an adapter with an inner thread. Containers with an inner thread require adapters with an outer thread.
  2. In our Online-Shop you will find the suitable adapter. All thread descriptions refer directly to the adapter. This means that if your container has a 3/4″ outer thread you will require an adapter with a 3/4″ inner thread. If you cannot find the necessary adapter here, or if you cannot determine the thread size, just send use a screw cap and we will send you a suitable adapter.


Your container thread is an outer thread with a diameter of 71 mm. You want to use a PP barrel pump with a barrel screw joint. Use the thread table to determine the type of thread. As it is a 71 mm thread you will require an adapter with a 71 mm inner thread. The barrel screw joint thread is 2″ BSP outer. This means that you need an adapter from 71 mm inner to 2″ BSP inner.

A (mm) B (mm) C (mm) Thread description Thread type
53 5 50,5 51 mm, DIN 51 Sawtooth
59-60 6 55,8 61 mm, DIN 60 Sawtooth
61 6 55,8 61 mm, DIN 61 Sawtooth
71 6 66,5 71 mm, DIN 71 Sawtooth
59 2,2 57,5 2″BSP/R2″ steel drum fine thread Standard
64,5 5 60 63 mm, 64 mm BSI Sawtooth
33,5 3 32,7 35 mm Round/Std
69,5 5,5 65 2″ coarse Mauser L-ring Sawtooth
56 3,5 52,5 Tri-Sure, 2″ coarse thread v. Leer, Tri-sure Sawtooth
63,2 4,25 57,5 US drum thread Sawtooth