Even though the steam trap is only a small, inexpensive component in comparison to other steam-plant equipment, the numbers used can range from several hundred in a large industrial steam plant to over 20,000 in refinery or chemical complexes. Steam traps never received much attention from most energy managers or system designers until the energy crisis of the 1970s.
The float, fixed orifice, and bucket steam traps were developed in the early 1900s. They were large, heavy, and expensive, operating on the principle that steam is a gas and condensate is a liquid. These traps are still used today and have changed little from their original design.