Control valve STEVI Vario - 448/449 | ARI

ARI STEVI Vario 448/449 – Process Control Valve

The ARI STEVI Vario 448/449 is a linear flow control valve with flanged connections and a threaded seat ring. It covers DN15–DN100 and is available in PN16, PN25, and PN40 versions, with bodies made from EN-JL1040, EN-JS1049, 1.0619+N, or stainless steel 1.4408.

Variants 448 and 449

• STEVI 448: Standard version with PTFE V-ring shaft sealing for -10°C to 220°C or optionally EPDM for -10°C to 150°C, suitable for water and steam up to 180°C.
• STEVI 449: Version with stainless steel bellows and graphite packing for -60°C to 400°C or bellows with PTFE V-ring up to 220°C. Selected when external shaft leakage needs to be minimized or higher operating temperatures are required.

Application Scope

Used in steam circuits, hot water, cooling, gases, and industrial fluids, with material compatibility checks for medium, temperature, pressure, and corrosion. The manufacturer states that valve selection remains the responsibility of the design engineer and material suitability must be confirmed.

Seat, Plug, and Leakage

Available with parabolic plugs with metal seat, PTFE soft seal, armored sealing edge, or perforated plug for noise reduction in gases and steam. Flow characteristics are modified equal percentage or linear. Seat tightness covers classes IV, IV-S1, and VI according to DIN EN 60534-4, depending on plug type and temperature.

Automation

The valve can be combined with a pneumatic actuator ARI-DP 30–34, air pressure 4–6 bar, or with an electric ARI-PREMIO-Plus 2G 2.2–15 kN, IP65, with handwheel and torque/travel switches. Connection of additional instruments is supported according to DIN IEC 60534-6.

FAQ

When is a perforated plug selected?
In steam or gases when pressure drop creates increased noise.

When is the 449 version required?
At high temperatures or when shaft leakage must be restricted with a bellows.

Key selection criteria: medium, flow rate, P1/P2, temperature, Kvs, permissible leakage, control signal, and fail-safe position.