One of the features that differentiates valves is the diameter inside the ball. The bigger this diameter is, the higher the flow capacity; smaller diameters reduce the amount of flow passing through the valve and may also create noise, turbulence and drop of pressure which could affect the overall performance of the whole system. In the common language of valves, there are typically 3 distinct families of flow diameters:
- In the full port ball valve (also named full bore) the design provides no restriction of flow when the valve is fully opened. This means obviously that the hole in the ball is of the same size as the pipeline: for example a 1” full port ball valve will be compatible with a 1” pipeline as it will have a DN 25 mm valve opening inside the ball. **
When a full port valve is in the open position, it’s like having a straight passage of flow with minimal pressure drop.
When a full port valve is in the open position, it’s like having a straight passage of flow with minimal pressure drop.
- In the reduced port (or reduced bore) ball valves, the opening in the ball is smaller than full port valves. Actually, it is precisely one size smaller. For instance, a 1” reduced port valve has a DN 20 mm size ball opening – same flow diameter as a 3/4” full port valve.
- In between full and reduced port is the standard port (also called nominal port); in this case flow is not full, but it is not so restricted as in the reduced port ball valves neither.
** But please pay attention: different standards do rule in different areas in the world setting different port definitions: for example in Europe a ½” ball valve to be full bore should have port 15 mm, and 14,5 is already considered a standard port. In USA on the contrary, a ½” ball valve, according to the US Standard Practice, with 12,7 mm port is full port!
When choosing a ball valve, we always recommend you to look at product datasheets, taking into account the specific application. In any case please feel free to contact your RuB Area Manager for clarification.
