Marine Bellows Drain Valve CB/T3297-1987

Operates based on changes in the liquid level height of condensate inside an adjustable bimetal steam trap, including: Float type: The float is a sealed hollow sphere.

Open-top float type: The float is an upward-open bucket shape.

Open-bottom float type: The float is a downward-open bucket shape.

Operates based on changes in liquid temperature, including:

Bimetal type: The element is a bimetal strip.

Steam pressure type: The element is a bellows or cartridge filled with volatile liquid.

Operates based on changes in the thermodynamic properties of the liquid.

Disc type: Due to the different flow velocities of liquid and gas under the same pressure, varying dynamic and static pressures are generated, driving the disc valve to operate.

Impulse type: As condensate at different temperatures passes through two-stage throttling orifice plates in series, varying pressures formed between the two stages drive the valve disc to operate.

Steam traps play a role in blocking steam and draining water in steam heating systems. Selecting the appropriate steam trap can maximize the efficiency of steam heating equipment. To achieve the desired effect, it is essential to understand the working performance and characteristics of various types of steam traps.

There are many types of steam traps, each with different performance characteristics. When selecting a steam trap, the primary consideration should be whether its features meet the operational requirements of the steam heating equipment. Only then should other objective conditions be considered. This approach ensures the selection of the correct and effective steam trap.

A steam trap must be able to "distinguish" between steam and condensate to effectively block steam and drain water. The "distinction" between steam and condensate is based on three principles: density difference, temperature difference, and phase change. Accordingly, three types of steam traps are manufactured: mechanical, thermostatic, and thermodynamic.

Mechanical type, also known as float type, utilizes the density difference between condensate and steam. Changes in the condensate level cause the float to rise or fall, driving the valve disc to open or close, thereby achieving the purpose of blocking steam and draining water. Mechanical steam traps have a small subcooling degree, are unaffected by changes in working pressure and temperature, drain water immediately, prevent water accumulation in heating equipment, and maximize heat exchange efficiency. With a backpressure rate of up to 80% and high working quality, they are ideal for process heating equipment.

Mechanical steam traps include free float type, free semi-float type, lever float type, inverted bucket type, etc.

The free float steam trap has a simple structure with only one moving part—a finely polished stainless steel hollow float, which serves as both the float and the opening/closing component. It has no vulnerable parts, ensuring a long service life. The YQ steam trap is equipped with a Y-series automatic air vent device, which is highly sensitive, automatically discharges air, and ensures high working quality.

When the equipment starts, air in the pipeline is discharged through the Y-series automatic air vent device. Low-temperature condensate enters the steam trap, the condensate level rises, the float ascends, the valve opens, and condensate is quickly discharged. Steam soon enters the equipment, rapidly raising its temperature. The thermosensitive liquid in the Y-series automatic air vent device expands, closing the air vent. The steam trap begins normal operation, with the float rising and falling with the condensate level to block steam and drain water. The valve seat of the free float steam trap is always below the liquid level, forming a water seal that prevents steam leakage and ensures energy efficiency. The minimum working pressure is 0.01 MPa, and it operates continuously within the range from 0.01 MPa to the maximum usage pressure, unaffected by temperature and pressure fluctuations. It can discharge condensate at saturation temperature with a minimum subcooling degree of 0°C, preventing water accumulation in heating equipment and maximizing heat exchange efficiency. With a backpressure rate exceeding 85%, it is one of the preferred steam traps for process heating equipment.

The free semi-float steam trap has only one moving part—a semi-float bucket with the opening facing downward. The bucket serves as both the opening/closing component and the sealing element. The entire spherical surface acts as the seal, ensuring a long service life, resistance to water hammer, no vulnerable parts, trouble-free operation, durability, and no steam leakage. The backpressure rate exceeds 80%, it can discharge condensate at saturation temperature with a minimum subcooling degree of 0°C, prevents water accumulation in heating equipment, and maximizes heat exchange efficiency.

When the device starts, air and low-temperature condensate in the pipeline enter the steam trap through the emission pipe. The bimetal air vent element inside the trap pushes the bucket open, opening the valve and quickly discharging air and low-temperature condensate. When steam enters the bucket, it generates upward buoyancy, and the temperature inside the trap rises, causing the bimetal air vent element to contract. The bucket drifts toward the valve port, closing the valve. When the steam inside the bucket condenses into water, the bucket loses buoyancy and sinks, opening the valve and quickly discharging condensate. When steam re-enters the bucket, the valve closes again, operating intermittently or continuously.

The lever float steam trap shares basic characteristics with the free float type. Its internal structure features a float connected to a lever that drives the valve core, opening and closing the valve based on the condensate level. The lever float steam trap uses a double valve seat to increase condensate discharge capacity, achieving a compact size with high discharge rates—up to 100 tons/hour. It is suitable for large heating equipment.



Marine Valves - Shanghai Yunlong Marine Valve Manufacturing Co., Ltd. is a manufacturer of marine valves compliant with standards such as JIS, GB/CB, ANSI, and DIN. Main products include marine butterfly valves, marine hydraulic control butterfly valves, marine electric butterfly valves, marine pneumatic butterfly valves, marine globe valves, marine gate valves, marine steam traps, marine safety valves, marine pressure reducing valves, marine self-closing valves, marine quick-closing valves, marine diaphragm valves, marine seawater filters, marine oil filters, marine stop-check valves, marine check valves, marine wafer check valves, marine stainless steel globe valves, marine bellows globe valves, marine fire valves, marine plug valves, marine storm valves, marine deck surface valves, marine boiler vent valves, marine sounding self-closing valves, marine level gauges, marine air vents, marine temperature control valves, marine pressure regulating valves, marine temperature regulating valves, marine sea valves, marine ball valves, marine breather valves, marine pressure reducing valve sets, marine safety valve sets, marine pipeline accessories, and other marine products. The company also provides certifications from various classification societies such as CCS, ABS, GL, LR, and DNV.