Advantages of PT Series 46 bimetal steam traps over thermodynamic disc traps

Operating efficiency

Thermodynamic disc (TD) traps lose about 2 lb/hr of steam during normal operation. The PT 46 does not lose any live steam because it discharges subcooled condensate. That translates to over $100 in annual energy savings per trap.

Mode of failure

TD traps fail completely open, resulting in heavy steam loss through the discharge orifice. In the PT 46, the bimetal plates always push the valve toward the seat: even in case of failure, the trap opens only slightly, minimizing steam loss.

Weather impact

In rain, snow, wind or other cold weather, the pressure in a TD trap's control chamber (the volume above the disc inside the bonnet) drops rapidly due to heat loss. This causes rapid cycling (50 to 70 cycles per minute versus the normal 2 to 3) and results in high energy loss and disc wear. The PT 46 reacts only to steam temperature change and discharges the increased condensate load accordingly.

Back pressure limitation

Back pressure in the return system greatly affects thermodynamic disc traps: the higher the back pressure, the faster the trap cycles, increasing steam loss. Generally, a TD trap's back pressure limit is 40% of its inlet pressure. The PT 46 has no such limitation; it operates at up to 99% of inlet steam pressure.

Additional considerations

• Unlike conventional TD traps, the PT 46's bimetal design is not subject to air binding.
• A thermodynamic disc trap will freeze when the steam line is shut off. The PT 46 self-drains, avoiding this issue.
• The PT 46 has a large seat orifice to easily handle dirt and the heavy condensate load during start-up.
• The PT 46 costs significantly less than most popular TD traps on the market.