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.