It is important to select the right size to ensure that the steam traps are able to effectively evacuate all the condensate formed in the distribution lines to avoid water hammer.
There are two types of condensation loads acting on the steam pipes. In a running system when the pipelines are already heated to steam temperature, losses occur due to radiation losses across insulation – this is known as the “Running Load”.
However when the distribution pipelines are isolated for a period of time, the lines eventually attain the ambient temperature. When steam is once again admitted to these cold lines, heavy condensation occurs as the steam is utilized to heat the cold pipes – this is known as the “Warm Up Load”.
The Warm Up Load is far greater than the Running Load. Thus the installed quantity of Drain Traps should not only be able to handle the “Running Load” but also the “Warm Up Load” and not only the Running Load.
If the steam traps cannot handle the warm up loads water hammer can occur in the system at start up.