Pressure reducing valve - Direct Acting for steam - REH20 | Miyawaki

Miyawaki REH20 Direct-Acting Steam Pressure Reducing Valve

The Miyawaki REH20 is a self-actuated steam pressure reducing valve, operating without external energy or impulse lines. The downstream pressure is detected in the internal control chamber, and the valve directly adjusts the opening to maintain the set point. It features a piston-operated design with an O-ring, eliminating the need for a diaphragm.

Technical Specifications

• DN15–DN200.
• Flanged connection DIN standard.
• Body: cast steel GP240GH / GS-C25 / 1.0619.
• PMA up to 4.0 MPa and TMA 400°C.
• PMO up to 2.8 MPa and TMO 400°C.
• Kvs 8–483 m³/h, depending on DN.
• p2 adjustment range: 0.05–1.6 MPa.
• Settings below 0.05 MPa or above 1.6 MPa require technical review.
• Maximum pressure reduction ratio: 25:1.

Operational Use

The REH20 is selected for steam lines with medium to high flow rates where pressure reduction is needed without pilot circuits or external pressure sensing. The 360° rotating conical disc minimizes unilateral seat wear, and soft sealing is available for leakage class VI requirements.

Difference from RE20 and REC20

The REH20 is the cast steel version for higher steam conditions compared to the RE20 ductile cast iron. The REC20 is chosen for stainless steel body 1.4408 requirements, while the REH20 is preferred in industrial steam lines demanding body 1.0619 and temperatures up to 400°C.

Applications

Typical applications include steam reduction stations, power plants, chemical and petrochemical processes, marine, food/beverage, and compact steam equipment. Selection requires p1, p2, steam flow, temperature, DN, Kvs, flange rating, and leakage requirement. For reduction ratios over 25:1, two-stage pressure reduction is considered.