Siemens Building Technology 257-02033 Valve Assembly

The Siemens 257-02033 is a 2-way normally open pneumatic valve assembly engineered for precise proportional control in heating and cooling applications. Built with a 1/2-inch NPT x Union Male connection, this unit features a 0.63 Cv rating and utilizes equal percentage flow characteristics to ensure linear heat transfer across varying load conditions. The forged brass body is paired with brass trim and a high-performance pneumatic actuator featuring a 3-8 PSI spring range. Designed for reliability in hydronic systems, this Siemens Powermite 599 series equivalent provides consistent modulating control when integrated into building automation systems. For contractors managing steam or chilled water terminal units, the normally open configuration ensures a fail-safe position during a loss of control air. This assembly is optimized for HVAC terminal unit control where tight shut-off and durable seat materials are required to prevent bypass leakage.

• Precise Flow Modulation: The equal percentage flow plug design provides superior control in the lower range of the stroke, ideal for terminal unit applications.
• Fail-Safe Operation: The normally open mechanical design ensures flow continues if pneumatic pressure is lost, protecting coils from freezing in specific climates.
• Durable Construction: The forged brass body and brass trim offer high corrosion resistance and a long service life in closed-loop systems.
• Easy Installation: The NPT by Union Male configuration allows for quick fitting and easy maintenance in tight mechanical spaces.

What is the maximum operating pressure for the 257-02033?
This 2-way valve assembly is typically rated for 250 psi static pressure, though it is critical to verify the specific medium temperature and actuator shut-off ratings for your application.

Can the spring range be adjusted on this pneumatic actuator?
The 3-8 PSI spring range is factory-set to provide specific sequencing; however, if your pneumatic control system requires a different start point, consult the 599 series technical documentation for compatible replacement springs.

Is this valve compatible with low-pressure steam?
Yes, the Siemens 257-02033 is suitable for low-pressure steam applications, provided the brass trim and seat materials meet the specific temperature requirements of your steam loop.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.