Product Introduction of Danfoss STC40-50M-148B4675 Straight-Through Stop Valve

Danfoss STC series manual stop valves feature Teflon valve discs and O-ring seals, ensuring higher safety. Available in sizes from DN 15 to DN 150, all models operate at a working pressure of 25 bar and are compatible with all common refrigerants, including ammonia.

Danfoss STC series manual stop valves offer:

? 100% online high-pressure testing ensures long-term trouble-free operation

? The STC manual stop valve has a unique back-sealing function, allowing easy replacement of stem packing under pressure without system shutdown, effectively reducing downtime

? Polished stainless steel stem and O-rings minimize the risk of external leakage

? Wear-free sealing surfaces combined with a bearing-type connection between the stem and valve core ensure product performance and extended service life

? High Kv value and low pressure drop reduce energy consumption

Main Technical Parameters:

? Refrigerant: Compatible with all common refrigerants, including ammonia

? Temperature Range: -50°C/+150°C (-58°F/+302°F)

? Maximum Working Pressure: 25 bar g (365 psi g)

Installation

During installation, the valve stem must be vertically upward or in a horizontal position (Figure 1). The valve should be opened manually without the use of tools or other devices (Figure 3). The valve is designed to withstand high internal pressure. However, the piping system design must avoid liquid traps to prevent damage from excessive pressure due to thermal expansion. The piping design should also provide effective protection against transient "liquid hammer" phenomena in the system.

Note!

The STC is a stop valve and must always remain fully closed or fully open. It must not be used in a partially open state.

Recommended Flow Direction

For optimal flow characteristics, the valve should be installed according to the flow direction indicated by the arrow on the valve body (Figure 2). The valve can also accept flow in the opposite direction (Figure 2), but this will slightly reduce the Kv-/Cv value.

Welding

Before welding, the bonnet should be removed (Figure 4) to prevent damage to the O-rings in the stuffing box, between the valve body and bonnet, and the PTFE washers on the valve core. Welding to the valve body requires materials compatible with the valve body material and appropriate welding methods. The valve interior should be cleaned to remove welding slag before reassembly. Clean promptly to avoid slag and foreign matter in the threads of the valve body and bonnet.

The bonnet does not need to be removed if the temperature in the area between the valve body and bonnet does not exceed +150°C/+302°F during welding.

This temperature depends on the welding process and the cooling of the valve body during welding (e.g., wrapping the valve body with a wet cloth for cooling). Avoid allowing dust, welding debris, or other foreign matter to enter the valve body during welding. Ensure the PTFE valve core sealing washers remain intact. After installation, the valve body must not bear external pressure (external loads). The outlet end of the stop valve must not be left open to the air after installation. The outlet side must always be connected to the system or sealed, for example, with a welded end plate.