Thermodisc Steam Traps
Thermodisc steam traps use flash steam velocity and pressure to move a free-floating disk to open and close a valve. Because the disc is the only moving part, the traps are rugged and resistant to damage.
This type of trap provides dependable performance for applications with light to moderate condensate loads. Thermodisc traps are excellent for high-pressure drip and steam tracing applications.
Operation of Thermodisc Traps:
At start-up, the disc is pushed off the seat by the inlet pressure and is held open by the impact force of the condensate hitting the disc.
As the condensate nears saturation temperature, flash steam will enter the seat-disc chamber at high velocity, lowering the pressure on the bottom of the disk. Some of the flash steam escapes to the area above the disc, causing the pressure above the disc to increase, pushing the disc closer to the seat.
At the instant the disc snaps closed on the seat, the pressure above the disc is approximately equal to the upstream line pressure. The disc is held closed because the pressurized area above the disc is much larger than the inlet area. The pressure above the disc decreases either by steam condensation or by non-condensables being removed via the micro-bleed channel on the disc.
When the pressure is low enough, the disc is pushed off the seat and the process is repeated.
Characteristics of Thermodisc Traps:
- Completely drains condensate at saturation temperature.
- Condensate is discharged close to steam temperature at all operating pressures.
- May be installed vertically, to drain trap body when steam is off, to prevent freezing.
- Compact size allows fitting in “tight” locations.
- Increase in cycling rate produces a distinct audible clicking sound that gives indication of wear before failure.
- Easily serviced in-line with replaceable seat and disc.
- Will tolerate water hammer, superheat, corrosive condensate and vibration.
- Audible “click” as disc seats may produce objectionable noise.
- Does not operate well at extremely low pressures or extremely high backpressure.
- Drains condensate from compressed air lines.
- Limited air-handling capability.
- Small passageways are sensitive to dirt, preventing tight closing of disc.
Primary Applications of Thermodisc Traps:
- Steam tracer lines where maximum temperature is required.
- Outdoor applications including drip traps on steam machines.
- Drying tables.
- Tire mold press and vulcanizing equipment.
- Dry kilns.
- Pressing machines.
- Rugged applications (superheat & water hammer).