Inverted bucket steam trap - ESH21 | Miyawaki

Miyawaki ESH21 – Inverted Bucket Steam Trap

The Miyawaki ESH21 is a mechanical inverted bucket steam trap constructed from cast steel SCPH2, designed for medium condensate loads in medium to high-pressure steam systems. Discharge is achieved through a bucket, lever, and seat mechanism, without an external actuator. Depending on the load, the discharge can be intermittent or nearly continuous.

Technical Specifications

• Sizes: DN15–DN25 / 1/2"–1".
• Connections: Flanged FF/RF or socket weld.
• Flange Standards: ASME/JPI, DIN, JIS.
• Body Material: Cast steel SCPH2.
• ESH21-21: PMO 2.1 MPa, Δp max 2.1 MPa.
• ESH21-45: PMO 4.4 MPa, Δp max 4.4 MPa.
• PMA: 4.4 MPa.
• TMA / TMO: 400 °C.
• Compliance: PED 2014/68/EU, Fluid Group 2, Category I, CE marked.

Operation and Selection

The inverted bucket closes the seat when steam is present and opens when condensate reduces buoyancy. A small vent hole at the top of the bucket removes hot air and non-condensable gases, reducing air locking. The series supports condensate recovery with backpressure up to 90% of upstream pressure, provided check valves and isolation valves are installed at the outlet.

Applications

Suitable for steam lines, heat exchangers, food processing, dyeing, cleaning facilities, and HVAC where a steel body and operation at higher pressures than cast iron series ES are required. Selection is based on condensate load, available differential pressure, backpressure, temperature, and connection type.

Installation and Maintenance

Standard installation is with horizontal flow, direction according to the arrow and nameplate on the top side. The steam trap is installed lower than the condensate-producing equipment. Blow-off is required before startup, with upstream/downstream isolation valves and maintenance space of over 230 mm above and 110 mm laterally. Service checks include filter, seat, valve, bucket, lever, and gaskets.