Inverted bucket steam traps use a buoyancy principle, an inverted bucket rises when steam enters (closing the valve) and sinks when condensate fills the bucket (opening the valve). This simple, proven mechanism provides reliable condensate drainage with continuous air venting through a small vent hole in the bucket.
AQ Process Systems sources and exports inverted bucket traps in cast iron, carbon steel, and stainless steel for pressures up to 175 bar. Available in sizes from 1/2" to 3" with threaded, socket-weld, and flanged connections. Suitable for a wide range of applications from drip legs to process heat exchangers.
Inverted bucket traps are valued for their resistance to water hammer, ability to handle dirt and scale, and long service life. They are one of the most energy-efficient trap types when properly sized and maintained.
| Product | Specification | Description |
|---|---|---|
| Standard IB Traps | ||
| Cast Iron Inverted Bucket Traps | 1/2", 2" | PN up to 17 bar | CI body | Low-pressure inverted bucket traps for heating systems, drip legs, and general utility steam applications. |
| Cast Steel Inverted Bucket Traps | 1/2", 3" | PN up to 100 bar | CS body | Medium-to-high pressure inverted bucket traps for process equipment, heat exchangers, and steam mains. |
| High-Pressure IB Traps | 1/2", 1" | PN up to 175 bar | Forged steel | High-pressure inverted bucket traps for power plant and refinery applications, forged body construction. |
| Specialty IB Traps | ||
| Stainless Steel IB Traps | 1/2", 2" | All-SS | Corrosive service | Fully stainless steel inverted bucket traps for corrosive condensate, clean steam, and hygienic applications. |
| Large-Capacity IB Traps | 2", 3" | High condensate load | Large-orifice inverted bucket traps for high-condensate-load applications, large heat exchangers, autoclaves, and drying cylinders. |
An inverted bucket hangs inside the trap body from a lever connected to a valve. When steam enters the bucket, it floats upward, pulling the lever and closing the outlet valve. As steam condenses inside the bucket, condensate fills it and the bucket sinks, opening the valve and discharging condensate. A small vent hole at the top of the bucket allows continuous air venting.
Inverted bucket traps offer excellent resistance to water hammer (the bucket simply rises and falls), long service life (few moving parts, robust construction), ability to handle dirt (particles settle to the bottom), continuous air venting (through the bucket vent hole), and energy efficiency when properly sized. They work well across a wide pressure range.
Inverted bucket traps are versatile and work well on steam mains, process heat exchangers, jacketed kettles, reboilers, drip legs, and equipment with fluctuating loads. They handle water hammer and pressure variations better than most trap types. They are less suitable for very light loads or intermittent operation where condensate may evaporate and cause steam loss through the vent hole.
Inverted bucket trap sizing requires the condensate load (kg/hr), operating pressure, and backpressure. Apply a safety factor of 2-3x the calculated condensate load to account for start-up and load variations. AQ Process Systems can size the correct trap from your equipment operating conditions.
Periodic inspection of the bucket, lever, valve, and seat. The most common maintenance items are valve and seat replacement (wear) and vent hole clearing (blockage reduces air venting). Internal parts are accessible through a bolted cover. With clean steam and proper straining, maintenance intervals of 3-5 years are typical.
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