Pilot Operated Diaphragm Type Pressure Reducing Valve for Steam
- Model: DP-2000
- Size: DN15-DN200 ( 1/2″-8″)
- Suitable for steam service
- Similar to YOSHITAKE GP-2000
- Inlet pressure: Max.1.6MPa
- Reduced pressure: 0.1~1.4MPa
- Body: Ductile cast iron
- Connection : PN16 / JIS 20K RF Flanged
Product Description
GENERAL
- This series Pressure Reducing Valve for steam are pilot-operated valves which can be used for small to large flow rate so that it is widely used in building utilities systems, air-conditioning systems and factory systems, etc.
- This pressure reducing pilot diaphragm valve for steam is aself-operated valve that has a high Cv value, and maintains anoutstanding level of control lability in primary pressure changes as well as steam equipments’ load fluctuations.
FEATURES
- 20:1 Maximum Pressure Turndown Ratio provides one-stage reduction without the customary costly two stage reduction.
- High Cv value and superb fow-controlling capacity allows even products that are one or two size smaller than the usual nominal diameter.
- Low pressure(0.21 kgf/cm2g) management is possible.
- Three different springs are employed based on the secondary pressure regulating range, thereby color-differentiating the pressure range based on the pipeline conditions.
- Simple structure, and major moving parts are made of durable stainless steel : removal of an adapter between the main valve and pilot valve enables easy repair and inspection.
How this pressure reducing valves work:
- The secondary pressure, which was reduced through the main valve, actuates the pilot diaphragm through the pressure sensing tube.
- This reduced secondary pressure adjusts the secondary pressure by responding to the force of the pressure regulating spring that is installed on the upper part of the pilot diaphragm.
- When the secondary pressure drops, the force of the pressure regulating spring becomes bigger than the force of the lower part of the pilot diaphragm, resulting in the diaphragm pushing downwards to open the pilot valve.
- When the pilot valve opens, the steam of the primary goes through the pressure regulating tube and reaches the lower part of the main diaphragm located at the lower end of the pressure reducing valve’s body.
- The main diaphragm overcomes the pressure of the return spring and opens the main valve. Steam is supplied to the secondary and thus the secondary pressure is adjusted.
- When the secondary pressure rises, it actuates the pilot diaphragm, thus adjusting the opening percentage of the pilot valve. The return spring pushes the main valve, and the steam of the lower part of the main diaphragm moves along the pipe and is discharged through the orifice.
- The steam pressure and pressure of the lower part of the main diaphragm adjusts the opening degree of the main valve according to load fluctuations, based on a balance maintained by the opening percentage of the pilot valve. This is how a constant secondary pressure level is maintained immediately after pressure changes oroad fluctuations.
Notes for selecting a size
1. When selecting a size, make room for an additonal 10 to 20% of flow, in consideration of such matters as pressure loss. There is especially a need to make substantial room when the pressure reduction ratio is high or the set pressure is 1 kgf/cm2 or less.
2. The secondary pressure of a pressure reducing valve changes according to fluctuations in the primary pressure as well as the flow. There is a need to determine a set pressure after considering the look up pressure and offset, and then select a size. (Refer to the pressure and flow characteristics curves.)
3. When the primary and secondary pressures are not constant, and change within a certain range, there is a need to select a size base on the primary and secondary pressures that have the minimum differential pressure.
4. lt is only natural that the flow becomes smaler when the size is to small. There are also issues when the flow is substantially bigger than needed. Such issues include hunching, chattering, and abnormal abrasion. Also, the minimum adjustable flow of a pressure reducing valve is 5% of the rated flow. It is recommended to avoid selecting a size that is based on this flow or smaller. When there are severe changes in summer and winter, attach two pressure reducing valves, one big and one smal, and use the valve appropriate forthe needed flow.