Control 3-way valve STEVI Smart - 450/451 | ARI

ARI STEVI Smart 450/451 – Three-Way Control Valve

The ARI STEVI Smart 450/451 is a three-way control valve designed for analog regulation in mixing or flow diverting operations. It covers DN15–DN150, PN16/PN25/PN40, with bodies made of EN-JL1040, EN-JS1049, 1.0619+N, or 1.4408. The connection is flanged, with face-to-face dimensions according to DIN EN 558 and flanges according to DIN EN 1092-1/-2.

Mixing / Diverting Operation

The basic configuration includes a mixing plug for two inlets and one outlet. For DN15–DN32, it can also be used for diverting service, while for DN ≥40, the appropriate choice for separation is the diverting plug, especially when tight shut-off or increased Δp is required.

450 and 451 Versions

• STEVI 450: Shaft sealing with PTFE V-ring from -10°C to 220°C, optionally EPDM, PTFE packing, or graphite.
• STEVI 451: Stainless steel bellows with secondary sealing, for applications where external leakage from the shaft must be minimized or operating temperature reaches up to 450°C, depending on configuration.

Trim, Leakage, and Control

Available with parabolic or V-port plugs, metal seat, optional soft PTFE sealing up to 200°C, and perforated plug for noise reduction in gases or steam. Standard seat leakage is Class IV according to DIN EN 60534-4, while with PTFE soft seal it can reach Class VI. The rangeability is 30:1.

Actuators and Automation

The valve can be combined with pneumatic ARI-DP 32–34T, maximum air pressure 6 bar, or electric ARI-PREMIO / PREMIO-Plus 2G and AUMA SAR. Handwheel, torque/travel switches, additional positioners, and explosion-proof versions are available as required by the installation zone.

Typical Applications

Used in heat exchangers, HVAC thermal circuits, hot water, steam, cooling networks, and industrial systems where bypass, mixing, or flow distribution is required.

FAQ

When to choose the 451?
For higher temperatures or when shaft emission must be limited with a bellows.

What is required for sizing?
Medium, flow rate, P1/P2, temperature, mixing/diverting operation, Kvs, allowable leakage, and fail-safe position.