Types of Pressure Regulating Valves
Release Date:
2023-02-15
Due to their intrinsic explosion-proof design and reliable performance, pneumatic control valves remain the dominant type both domestically and internationally. In the past, small-flow control valves officially manufactured in China could operate at pressures up to 100 kg/cm², with rated flow coefficients (Cv) ranging from 0.05 to 0.0012. These valves featured a seat bore diameter of 3 mm, a cylindrical valve plug with one or more V-shaped grooves, a stem travel of 6 mm, and were supplied without a matching positioner, resulting in relatively poor control accuracy.
Due to their intrinsic explosion-proof design and reliable performance, pneumatic control valves remain the dominant choice for control valve applications both domestically and internationally.
In the past, domestically produced small-flow regulating valves could operate at pressures up to 100 kg/cm², with rated flow coefficients (C values) ranging from 0.05 to 0.0012. These valves featured a seat orifice diameter of 3 mm and a cylindrical valve plug with one or more V-shaped grooves machined on its surface. The stem travel was 6 mm, and the valves were not equipped with positioners, resulting in relatively poor control accuracy.
China has also introduced small-flow regulating valves. These valves have a flow capacity of approximately 0.001, with a cylindrical valve plug featuring a notch. They are designed for a working pressure of 300 kg/cm², a stem travel of 7/16 inch, and a conical valve plug, and are equipped with a top-mounted positioner manufactured by Moore.
Valves of the type described above are characterized by their simple structure and light weight. The commonly used seat bore sizes range from 1/8 to 1/4 inch (approximately 3.175 to 6.35 mm), with stem travel ranging from 1/4 to 1/2 inch (6.35 to 12.7 mm). These valves can achieve flow capacities as low as 0.00006, or even lower.
In general, cylindrical-slit spools exhibit better characteristic performance than conical spools; the former can achieve the desired flow characteristics by adjusting the slot depth. However, the latter offers superior adjustability because the fluid passing through the valve is distributed evenly around the entire circumference of the spool cross-section. Such valves are commonly used in applications where high precision is not required, but they suffer from poor capacity accuracy and limited repeatability of flow characteristics.
The flow capacity of a valve is primarily determined by the diameter of the flow orifice. For a 1/16-inch orifice, the theoretical Cv value is approximately 0.06, which essentially represents the upper limit for low-flow applications. To further reduce the flow rate, it is necessary to fundamentally decrease the stem travel or to restrict the opening of the flow orifice.
Previous
Phone
Address
No. 99, Baiyun Road, Economic and Technological Development Zone, Hefei City, Anhui Province
