Mechanical traps sense the difference in density between steam and condensate. Condensate from this type of trap is continually discharged, leaving none to hinder the process. These types of traps are the most commonly used in systems that require large discharge capacities, such as process applications.
The bucket trap uses an inverted bucket as a float device, and a linkage connects the bucket to the valve head. When steam or air enters the bucket, the bucket gains buoyancy and closes the valve. Condensate causes the bucket to lose buoyancy and sink, opening the valve and allowing the removal of the condensate.
The floating ball trap is a similarly simple mechanical trap. The weight of the ball, acting through a lever, keeps the valve closed when there is no condensate. As the condensate enters the trap, it raises (floats) the ball and opens the valve. When the condensate has been discharged, the ball drops back down and closes the valve. This type of trap is unable to discharge air, so a thermostatic air vent is installed inside the body of the valve for this purpose.
The Cameron portfolio of DOUGLAS ITALIA steam trap and strainer technologies offers both inverted bucket and floating ball traps.