pilot-operated (before valve) pressure control valve is composed of the
control valve ,pilot and actuator. It is suitable for controling differential pressure in the pipes of
non-crrosive liquids, gases and steams. when the diferential pressure rises, the control valve is
opened The main features are as follows:
1.It has the pressure balancing function with high sensitivity.
2.Low noise, reliable performance, free of maintenance
3.The standard modular design is adopted.
4.High control precision
Technical parameters and performances
Body
DN | DN15 20 25 32 40 50 65 80 100 125 200 250mm | |
PN | PN1.6 4 .0MPa | |
Flange standard | ANSI JIS DIN GB JB(special standards can be offered according to user requirements) | |
Body material | Cast iron (HT200), cast steel (ZG230-450), cast stainless steel (ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2T i) | |
Plug material | Hard seal | Stainless steel (1Cr18Ni9Ti, 1Cr18Ni12Mo2Ti) |
Soft seal | Stainless steel embedded with rubber ring | |
Pressure balancing | Stainless steel bellows (DN15~125), balanced diaphragm (DN150~250)
| |
Actuator
Effective area (cm2) | 250 |
Pressure setting range | 0.01~0.12 0.08~0.25 0.2~0.5 0.45~1 0.6~2.0 |
Minimum differential pressure that ensures normal work of the pressure valve | DN15~125is 0.08 DN150~250is 0.1 |
Allowable maximum differential pressure between the upper and lower diaphragm chambers | 0.4 |
Material | galvanized steel sheet; diaphragm: EPDM or FKM with fiber |
Control pipeline connection | Copper pipe o r steel pipe Φ10X 1(mm); ferrule connect ion: R1/4" |
Note: ※T he pressure setting range corresponding to the effective area does not apply to valves with DN150-250.
Performance
Set value error | ±4% | |
Allowable leakage (under stipulated testing conditions) | Hard seal | 4x0.01% valve rated capacity |
Soft seal | DN15~50 DN65-DN625 DN150~250 | |
10 bubbles/ min 20 bubbles/min 40 bubbles/min | ||
Set value error ±4%
Allowable leakage Hard seal 4x0.01% valve rated capacity
(under stipulated DN15~50 DN65~125 DN150~250
testing conditions) Soft seal 10 bubbles/min 20 bubbles/min 40 bubbles/min
Structural figure
1Body | 2Seat | 3 Stem | 4 Before-valve pressure P1 pipe | 5 Balanced bellows | 6Travel indicator | 7 Diaphragm | 8 Spring |
9 Operating pressure Ps pipe | 10 After-valve pressure P2 pip | 11 Pilot | 12 Pilot plug | 13Spring | 14 Bellows | 15 Adjusting screw | 16 Adjustable needle valve |
Allowable working temperature
DN | 15~125mm | 150~250mm | |
seal type | Hard seal | ≤150℃ | ≤140℃ |
Cooling tank≤200℃ | Cooling tank and extension ≤200℃ | ||
Cooling tan k and heat sink ≤350℃※ | Cooling tank and extension ≤300℃※ | ||
Soft seal | ≤150℃ | ||
Note: ※It indicates the allowable working temperature is valid only when the medium is steam
Rated flow coefficient, noise measuring coefficient, allowable differential pressure
DN | 15 | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 125 | 150 | 200 | 250 |
Rated flow coefficient | 4 | 6.3 | 8 | 16 | 20 | 32 | 50 | 80 | 125 | 160 | 280 | 320 | 450 |
Noise measuring coefficient Z value | 0.60 | 0.60 | 0.60 | 0.55 | 0.55 | 0.50 | 0.50 | 0.45 | 0.40 | 0.35 | 0.30 | 0.20 | 0.20 |
Allowable differential | PN16 | 1.60 | 1.50 | 1.20 | 1.00 | ||||||||
pressure (Mpa) | PN40 | 2.00 | |||||||||||
Working principle
After throttling by the plug and seat, the before-valve pressure P1 of the process medium is changed into the after-valve pressure P2. Through the control pipeline, P1 is input to the upper diaphragm chamber of the actuator and acts on the top disc. The acting force produced balances the reacting force of the spring, determining relative positions of the plug and seat and controlling the before-valve pressure. W hen the before-valve pressure P1 increases, the acting force of P1 that acts on the top disc will increase accordingly. At the time, the acting force on the top disc is higher than the reacting force of the spring to make the plug move away from the seat, until the acting force on the top disc balances the reacting force of the spring. At the time, the flow area between the plug and seat is increased, the flow resistance becomes lower and P1 is reduced to the set value. Likewise, when the before-valve pressure P1 decreases, the acting direction is reverse to the above. This is the working principle during the control of before-valve pressure. When it is necessary to change the set value of before-valve pressure P1, please adjust the adjusting nut.
