Miyawaki ESU5 – Inverted Bucket Steam Trap, Stainless Steel Construction
The Miyawaki ESU5 is a mechanical inverted bucket steam trap designed for small to medium condensate loads. Constructed from stainless cast steel SCS13A / CF8, it is suitable for steam lines requiring enhanced corrosion resistance compared to cast iron versions.
Technical Specifications
- Sizes: 1/2", 3/4", 1".
- Connections: Rc, NPT, JIS / ASME / DIN flanges, socket weld.
- PMA: 2.1 MPa.
- TMA / TMO: 350 °C.
- PMO per version: ESU5-3 at 0.3 MPa, ESU5-7 at 0.7 MPa, ESU5-11 at 1.1 MPa, ESU5-16 at 1.6 MPa, ESU5-21 at 2.1 MPa.
- Body Material: SCS13A / CF8.
- Compliance: PED 2014/68/EU, Article 4, Section 3, without CE marking.
Operation
The inverted bucket operates the valve assembly based on buoyancy. When condensate accumulates, the bucket loses buoyancy and the seat opens. With steam entry, the bucket rises and the valve closes. A small vent hole at the top of the bucket removes hot air and non-condensable gases, reducing air locking phenomena.
Applications
Suitable for:
- heat exchangers,
- unit heaters and heating elements,
- dryers and small steam processes,
- food or pharmaceutical equipment,
- lines requiring stainless steel body.
Supports condensate return with back pressure up to 90% of upstream pressure, provided check valve and isolation valve are installed at the outlet.
Installation and Maintenance
Install with horizontal flow from inlet to outlet and nameplate on top. The steam trap should be positioned lower than the condensate-producing equipment. Maintenance space of over 120 mm is required, and line blow-off before startup is necessary.
FAQ
When to choose over ES5?
When SCS13A / CF8 material is necessary due to corrosion, installation cleanliness, or project specification.
What causes reduced flow?
Exceeding operating pressure, insufficient sizing, clogged vent hole, or debris in the seat.





