Thermodynamic steam traps operate on the principle of differential pressure across a flat disc, the disc opens to discharge condensate and closes when flash steam forms beneath it. Their simple, single-moving-part design makes them extremely reliable and tolerant of water hammer, vibration, and superheated steam.
AQ Process Systems sources and exports thermodynamic traps in carbon steel and stainless steel for pressures up to 120 bar and temperatures up to 450°C. Available with threaded, socket-weld, and flanged connections in sizes from 1/4" to 1", with universal connectors for easy installation.
Thermodynamic traps are the preferred choice for steam main drip legs, tracer lines, and any high-pressure steam application where compact size, high-pressure capability, and resistance to freezing damage are required.
| Product | Specification | Description |
|---|---|---|
| Standard TD Traps | ||
| Thermodynamic Disc Traps | 1/4", 1" | PN up to 120 bar | CS or SS body | Standard disc-type thermodynamic traps, single disc, bolted cap. For steam mains, drip legs, and general high-pressure condensate drainage. |
| TD Traps with Integral Strainer | 1/2", 1" | Built-in strainer screen | Thermodynamic traps with integral strainer element, combining trap and strainer in one compact body, reducing installation components. |
| Special TD Traps | ||
| Superheat TD Traps | Up to 450°C | Hardened disc and seat | Thermodynamic traps designed for superheated steam service, hardened disc and seat materials withstanding high-temperature erosion. |
| Universal Connector TD Traps | Multi-position mounting | Swivel connector | TD traps with universal swivel connectors allowing installation in any orientation, simplifying field installation and reducing fittings. |
| Stainless Steel TD Traps | All-SS construction | Corrosive condensate | Fully stainless steel thermodynamic traps for corrosive condensate, clean steam, and food/pharmaceutical applications. |
A flat disc sits on a seat with an annular orifice. When condensate arrives, it lifts the disc and flows through. As it passes through the orifice, it flashes to steam, the high velocity creates a low-pressure zone above the disc, while the flash steam pressure in the chamber above pushes the disc down, closing the trap. The trap remains closed until the flash steam condenses and pressure above the disc drops, allowing the next batch of condensate to lift the disc.
Thermodynamic traps excel in steam main drip legs, tracer lines, high-pressure applications (up to 120 bar), and superheated steam lines. They are compact, handle water hammer well, are resistant to freezing damage (the disc simply lifts), and have no adjustment or calibration required. They are not ideal for very low-pressure steam (<1 barg) or applications requiring continuous condensate discharge.
With proper installation and clean steam, thermodynamic traps can last 5-10+ years. The disc and seat are the only wear parts, replacement takes minutes. Lifespan depends on steam quality, cycling frequency, and whether dirt is kept out by upstream straining. We supply spare disc and seat kits for all models.
Yes. Thermodynamic traps are one of the few trap types that handle superheated steam reliably. The superheat variants use hardened disc and seat materials (Stellite or ceramic) to resist erosion from high-temperature flash. Standard TD traps handle moderate superheat; dedicated superheat models handle up to 450°C.
Thermodynamic traps discharge condensate in intermittent bursts, there is a brief moment of flash steam at each discharge. This is normal operation, not live steam loss. A properly functioning TD trap discharges condensate efficiently with minimal steam loss. If the trap cycles continuously (rapid opening/closing), it may indicate oversizing, air binding, or a worn disc.
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