DISC TYPE THERMODYNAMIC STEAM TRAPS

This type of steam trap operates by the internal energy and pressure of steam. Condensate that reaches to trap raise the disc and open the orifice and flow continuously by the help of the steam pressure which is behind the condensate through the discharge orifice. Steam entering the trap expands suddenly as it reaches the backside of the disc. The resulting high flow velocity causes a decrease in pressure under the disk. Steam above the disc gets high pressure force and this pressure balance forces the disc onto the seat to close the orifice in other words to trap the steam. When condensate appears at the trap inlet under and above the disc the pressure force above the disc disappears and allows the condensate discharge and this cycle repeats. 

Operation Principals;

The principal of the thermodynamic steam trap is based on Bernoulli’s law, which states that the sum of the static pressure and dynamic pressure is constant at all points in a fluid flow. If cold condensate flows into the steam trap on start-up, the valve disc is forced upwards and the condensate is discharged from the outlet holes. The trap is fully open. As the start-up phase progresses, the condensate becomes hotter and the pressure rises. Part of the static pressure is then converted to velocity in the chamber between the seat and the disc. 

Advantages of Thermodynamic Steam Traps:

1- No adjustment required: Thermodynamic traps can operate across their entire working range without any adjustment or change of internals. 

2- Body design: They are compact, simple, lightweight and have a large condensate capacity for their size. 

3- High Pressure Use: Thermodynamic traps can be used on high pressure and superheated steam and are not affected by water hammer or vibration. 

Disadvantages of Thermodynamic Steam Traps: 

1- Stuck Risk: During the start-up, high amount of air may come in the steam trap and stuck the disc. This may cause water hammer. 

2- Opposite Pressure: If the opposite pressure exceeds 80% of the inlet pressure, disc loses its function, likely if the system pressure drops below 0,25bar, disc can’t operate. 

3- Insulation: Horizontal installation obligation may cause trouble at some applications.