TD42 Thermodynamic Steam Trap, Carbon & Stainless Steel

The TD42 is a thermodynamic disc steam trap for removing condensate from saturated steam lines. Its only moving part is a hardened disc that seats on and lifts from a pair of concentric faces, so the trap has no linkages or floats to fail and tolerates waterhammer and superheat.

At start-up, cold condensate lifts the disc and passes to the outlet. As the condensate approaches steam temperature it flashes as it crosses the seat; the high velocity of that flash steam beneath the disc lowers the pressure under it while flash steam collects in the chamber above the disc and snaps it shut. The trap reopens when the pressure in the chamber above falls, so discharge is intermittent rather than continuous. A minimum differential pressure across the trap is needed for it to cycle, and excessive backpressure will hold it open.

Typical duties are steam main drainage, steam tracing and drip legs on distribution headers, where an intermittent blast discharge is acceptable. The units illustrated have an integral Y-type strainer with a screwed cap, so the screen can be cleaned without breaking into the pipework, and the top cap unscrews to give access to the disc and seat.

When ordering, specify nominal size, thread form (BSP or NPT), and body material - carbon steel or stainless steel - together with the maximum working pressure and the backpressure of the condensate system, and confirm the discharge capacity required for the duty with the supplier. Discharge capacity and steam loss for automatic steam traps are determined by the test methods of ISO 5117.