STEAM TRAPS Introduction Steam Trap Selection Guidelines
Thermodynamic Traps: The Thermodynamic Trap is simple and compact with a single moving part (disc) which opens to discharge condensate and closes in the presence of steam. Body materials available are Stainless and Alloy Steels for pressures up to 3,600 psig. Typical Applications: Widely used on higher pressure drip applications and critical tracing applications (where condensate back-up is not permitted). Advantages: Rugged design, operation is easy to check due to distinct cyclic operation, relatively small with lower capacities, single model operates over wide pressure range in contrast to mechanical traps, excellent for superheated steam, self-draining when mounted vertically to prevent freezing. Other Factors to Consider: Limited air venting, wet climates can increase cycle rates, sensitive to excess back pressure, blast discharge may not be preferred in some systems Thermostatic Traps: A Thermostatic Trap contains a heavy-duty, industrial-purpose welded stainless steel thermal element designed to control condensate discharge by sensing the temperature difference between steam and cooler condensate (also bimetallic designs). Body materials available are Cast Iron, Stainless and Alloy Steels with thermal element designs available for pressures up to 650 psig and bimetal designs to 2,260 psig. Typical Applications: Extremely versatile and energy efficient, these traps are suitable for a wide range of applications. Thermal element designs are suitable for applications ranging from general service drip and tracing applications to small-to-medium batch style processes. Bi-metal designs can be used in high pressure, superheated drip applications or in lower pressure tracing applications. Advantages: Self-draining when mounted vertically to prevent freezing, single model operates over wide pressure range in contrast to mechanical traps, small and compact with similar capacities to larger mechanical traps (F&Ts & IBs), superior air venting capabilities, welded stainless steel thermal element and bimetal elements are extremely rugged, moderate discharge due to reduced flash steam, choose between fail-open or fail-closed bellows. Other Factors to Consider: Some condensate back-up can be expected, thermal element design not recommended for superheated applications. Inverted Bucket Traps: The Inverted Bucket Trap uses an inverted bucket as a float device to control the opening and closing of the disc and seat to discharge condensate. Body materials available are Cast Iron and Stainless Steel for pressures up to 450 psig. (IB traps are referred to as mechanical traps.) Typical Applications: These traps have a discharge orifice positioned at the top of the trap body which make them ideal for drip applications on systems containing excessive pipe scale and debris. They may be considered for process applications where air venting is less of a concern or handled by a separate air vent. Advantages: Rugged and simple design, top-mounted discharge orifice less susceptible to failure from dirt and debris, service life often exceeds other style traps. Other Factors to Consider: Limited air venting capabilities, can lose its prime causing it to fail, narrow operating pressure ranges require more care during selection, not self-draining therefore subject to freezing, single position installation, fixed orifice on bucket allows small steam leakage, physical size can be large and require additional support.
Most Common Use: General service drip & tracing applications above 30 psig, as well as high-pressure drip applications with superheat.
Most Common Use: Industrial style Thermostatic Traps are extremely versatile. Their use can range from general service drip & tracing applications to small-to-medium process heating applications.
Most Common Use: Used on drip applications
where excessive dirt and debris may be of significant concern. They can serve as alternatives to F&T's in process applications where air venting is not required by the steam trap.
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