Steam Traps & Steam Trapping

Steam traps & Steam Trapping

During the heating process the steam is converted into condensate.  Steam Traps  will allow this condensate to pass through it into the condensate return lines and at the same time  will  hold  back  the  steam within the heat exchanger or whatever the steam is applied to, such as a steam main drainage application.

There are three points, which are fundamental about the use of steam traps:

  •    selection of the best type
  •    choosing of the correct size
  •    the right installation

It   can  be claimed that the  majority of steam traps will "work" on any  application ( provided  that  the  operation conditions fall within the pressure range and condensate discharge capacity of the trap). However, we do not just want steam traps which "work" moderately well. We must aim to achieve maximum output and efficiency from all steam using plants. This means selecting the best trap to suit each particular job.

The benefits of selecting the best type of steam trap for a given application will be  wasted  if the trap is not sized correctly. It is a bad practice to choose a 20 mm trap simply because it has to go on a 20 mm drain pipe.

In order to size a trap we obviously need to know the quantity of condensate to be handled in a given  time and steam pressure. The  manufacturers  of standard steam  equipment usually supply  reliable figure  on  the condensation  rates of their equipment. If  such  information  is not available,  it has  to be acquired either by calculation or practical measurement of the condensate produced. Steam will condense most rapidly on start up when steam system is cold. It is for this reason that it is common practice to size traps to  handle  twice  as  normal  running  load of  the plant in  question. An undersized trap  will  cause water logging of the steam space when it is least affordable.


The most suitable type of trap for temperature controlled applications and processes is the continuous discharge Single Orifice Float Trap  with  inbuilt  air  release  ( or steam  lock  release,  if  necessary ). This  trap  will  discharge  condensate steadily as it is formed  without  upsetting  pressure conditions in the steam space. It will not steam lock or air lock or attempt to control the discharge temperature of the condensate.

Wherever  possible, both  water hammer  and water logging should be prevented by allowing the discharge from the steam trap to run away by gravity.