Since 1933 MIYAWAKI develops and manufactures high-quality equipment for a wide range of steam and condensate lines.


Thermodynamic steam traps operate on the basis of the Bernoulli principle, depending on the relationship between the velocity and the pressure exerted by the condensate and steam inside the steam trap. They have only one moving part - the disc.

Due to their compact design and cost effectiveness thermodynamic steam traps are widely used in applications where the condensate must be removed immediately from steam lines and steam equipment. They discharge the condensate near the saturation temperature.

The traps may operate up to a back pressure of 80% of the inlet pressure, but for smooth operation it is recommended that the back pressure does not exceed 50% of the inlet pressure. Thermodynamic steam traps discharge the condensate intermittently.

All steam traps are equipped with a hardened stainless steel disc and seat. After the lapping process all disc surfaces are controlled individually before releasing them for use in steam traps. These features and very high and severe quality standards for the whole production process give MIYAWAKI`s thermodynamic steam traps a long and reliable service life.


S31N Ductile Cast Iron Steam Traps with replaceable internals
SC,SF Cast Iron Steam Traps for high capacity
SC31 Stainless Steel Steam Traps with replaceable internals
SD1, SU2N, SU2H Stainless Steel Steam Traps for low to high pressure applications
S55N, S61N, S62N Forged Steel Steam Traps for high pressure applications
SV Steam Traps with inbuilt bypass
SL3 Compact, very small trap for low capacity applications


  • Immediate discharge of condensate
  • Insensitive to waterhammer, superheated steam and freezing
  • Most types contain a bimetal ring which improves the ability of the trap to discharge air and cold condensate quickly at start-up and prevents air locking during times of operation
  • Can be installed in any position
  • In case of danger of air locking special discs available
  • All traps equipped with additional cover for reduced frequency of cycling and energy savings
  • All traps with inbuilt strainers (except SL3)
  • Easy maintenance

Suitable for

light to medium condensate loads: steam tracing, steam main drips, small heat exchangers, unit heaters, sterilizers and many other applications in the petrochemical, chemical, textile, food, pharmaceutical and further industries.

Series SV Thermodynamic steam traps with inbuilt bypass are designed for special applications in the food, pharmaceutical or other industries or for laundry applications where costs and space must be saved.

Operating principle

cold condensate

hot condensate


At the time of start up the pressure of the incoming cold condensate and air raise the disc and water and air are discharged quickly.

When hot condensate flows into the trap, the trap is still open and the hot condensate can be discharged quickly.

After hot condensate flows into the trap, steam enters it. As the velocity of the fluid increases, the pressure under the seat exerted by the steam decreases. At the same time the pressure in the pressure chamber above the disc increases. The disc is pressed down and closes.

While hot condensate flows into the trap, the trap remains closed for a certain period, as far as the steam inside the pressure chamber does not condense. The more condensate flows into the trap, the more the temperature cools down. The steam inside the pressure chamber also cools down and condenses. As a result, the pressure of the incoming condensate raises the disc and condensate is discharged. Cycles 2, 3 and 4 repeat.