Email this pageWhat is a Steam Trap?
The steam trap is one of TLV's most representative products, but first and foremost, just what is a steam trap?
The literal meaning of steam trap of course is something that traps steam. They came to be called this because they are used on applications where only the condensate is to be discharged from a steam-filled space, with no steam leakage possible.
A 'steam trap' is defined by ANSI in the following way:
steam trap - Self contained valve which automatically drains the condensate from a steam containing enclosure while remaining tight to live steam, or if necessary, allowing steam to flow at a controlled or adjusted rate. Most steam traps will also pass non-condensible gases while remaining tight to live steam.
ANSI/FCI 69-1-1989
Traps are a type of automatic valve.
For What Purpose are Steam Traps Installed?
Why are steam traps necessary when steam is used for heating? Steam is a gas that is formed when water is at high temperatures and under high pressures, but when its work is done (= it has given up its latent heat) steam condenses and becomes condensate. In other words, condensate does not have the ability to do work that steam does. It is because of this that, whether in steam transport piping or in a heat exchanger, condensate must be targeted for rapid removal.
The Reason Steam Traps are Necessary (Example: Jacketed Kettle)
What's Wrong with Using a ‘Normal' Valve?
Some of you may be thinking, 'But can't you get the same result by using a valve without using a steam trap, if you simply adjust the amount of valve opening so that exactly the amount of condensate generated is being discharged?'
This works for a limited set of conditions, but since the range of conditions is extremely limited, it is not a realistic solution.
The largest problem with having the degree of valve opening set at a fixed amount is that it can't change in response to fluctuations in the amount of condensate generated. The amount of condensate generated is not fixed. In the case of equipment, the amount of condensate generated at start-up differs from the amount generated during normal operation, and fluctuations in the product load also result in fluctuations in the amount of condensate generated. In the case of steam transport piping, the amount of condensate generated may differ as outdoor air temperatures fluctuate and as a result of heavy rains or snow.
If the device can't respond to fluctuations in condensate load, condensate that should be discharged will instead pool inside the equipment/pipe, and steam leakage that should be prevented will occur.
Having the Valve Opening Amount at a Fixed Setting Instead of Using a Steam Trap
Steam Traps Come in Various Different Mechanisms
Various types of mechanisms (operation principles) have been developed for automatic discharge in steam traps, but among the ones most widely used at present are one that utilizes temperature, one that utilizes the difference in the specific gravities of condensate and steam, and one that utilizes change in pressure caused by temperature change and kinetic energy. Each of these types of steam trap has its own characteristics.
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