American Fairchild control valve 63252NSG available now.

Brand

FAIRCHILD/Fairchild Semiconductor (USA)

Application Areas

Chemical, Petroleum, Mining, Road/Rail/Marine, Comprehensive

FAIRCHILD Control Valves

FAIRCHILD Frequency Converters

FAIRCHILD Controllers

FAIRCHILD Water Separators

FAIRCHILD Pressure Regulators

FAIRCHILD Control Valves Selection:

FAIRCHILD control valves are actuators in automated control systems, and their application quality directly reflects the system's regulation quality. As terminal components in process control, their importance is now widely recognized. Besides the product's own quality and correct installation, use, and maintenance by the user, accurate calculation and selection are crucial for the successful application of control valves. Errors in calculation and selection can cause intermittent system operation, and in some cases, render the system unusable. Therefore, users and system designers must recognize the importance of valves in the field and pay sufficient attention to the selection of control valves.

Principles of FAIRCHILD Control Valve Selection

1. Select the appropriate structural form and materials based on process conditions.

2. Select the flow characteristics of the control valve based on the characteristics of the process.

3. Select the appropriate control valve diameter based on the process operating parameters.

4. Select the necessary auxiliary devices based on the process requirements.

5. Select the appropriate actuator. The response speed of the actuator should meet the process requirements.

Types and Selection of FAIRCHILD Control Valves in the Power Industry (USA)

1. Feedwater Valves: Main and auxiliary boiler feedwater valves, combined feedwater regulating valves

Control Requirements: Control boiler feedwater to maintain boiler liquid level and steam flow.

Operating Condition Requirements: During boiler startup, the valve differential pressure can reach 100-300 kg, with a relatively small flow rate. During normal operation, the differential pressure is small, the flow rate is large, and the flow rate adjustment ratio is 75:1-100:1.

Valve Requirements: Valve body material is WCB/WC9. For the starting valve in a dual-valve system, cavitation resistance and a Class V shut-off rating are required. For combined feedwater valves, specialized valve internals are required to meet the needs of both boiler startup and normal operation. 1. **Generally, the valve should be selected for fail-safe operation.** (Note that hydrazine is often added to the feedwater to remove dissolved oxygen, which can adversely affect SATELLITE 6 alloy or similar alloys. Therefore, it's best to avoid using 316 SATELLITE for internal valve components and instead use 416 stainless steel.)

2. **Boiler Feed Pump Minimum Flow Circulation Valve**

Control Requirements: Ensures safe start-up and operation of the boiler feed pump, preventing pump damage caused by insufficient flow, increased temperature rise, or severe cavitation. (Older power plants may use on/off type minimum flow control valves, as well as mechanical automatic pump circulation valves.)

Operating Conditions: Pressure drop reaches 160-350 kg, making it the valve with the greatest pressure differential in the power plant system. Flow rate is typically 30% of normal flow.

Valve Requirements: Cavitation resistant, anti-clogging structure, Class V sealing rating. The valve operates continuously during pump start-up and shutdown. After normal pump start-up, the valve closes, and the valve is typically fail-safe open.

3. High/Low Temperature Heater Feedwater Heater Drainage, Condensate Heater Drainage

Control Requirements: Control the condensate level in the heaters and drain it promptly, i.e., high water level discharge, normal water level drainage.

Operating Conditions: The medium is saturated water. The pressure difference between the control valves between heaters is generally 6-30 kg. The last-stage drain valve is directly connected to the condenser or deaerator.

Valve Requirements: Resistant to flash erosion, V or VI sealing class, valves are usually fault-open.

4. Deaerator Water Level Control Valve

Control Requirements: Provide flow to maintain the normal water level in the deaerator, and increase the water temperature by adding steam to eliminate dissolved gases in the water.

Operating Conditions: During startup, the flow rate is low and the pressure difference is high; under normal conditions, the flow rate is high and the pressure difference is low, similar to the feedwater valve.

Valve Requirements: Effectively resist cavitation at low flow rates.

5. Desuperheating Valve (Desuperheater)

Control Requirements: Injects high-pressure water into steam to achieve the required steam temperature.

Operating Conditions: Medium is water, pressure differential is large. Valve Requirements: Various types: nozzle type, auxiliary atomizing type, self-contained type, and wafer type.

6. Desuperheating and Pressure Reducing Valve (High and Low Pressure Bypass Valve)

Control Requirements: Adjusts high-temperature, high-pressure steam to a specific temperature and pressure; provides a bypass channel for the turbine, allowing the boiler to operate independently of the turbine.

Operating Conditions: Desuperheating and pressure reducing of high-temperature, high-pressure steam.

Valve Requirements: Resistant to thermal shock, noise reduction, and rapid response.

FAIRCHILD Control Valve Selection Requirements for Accessories:

During production, control systems impose various special requirements on valves. Therefore, control valves must be equipped with various auxiliary devices (hereinafter referred to as accessories) to meet the needs of the production process. Control valve accessories include:

1. Valve positioner: Used to improve the working characteristics of the control valve's regulating performance and achieve correct positioning.

2. Valve position switch: Displays the upper and lower limit travel positions of the valve. 3. Pneumatic position-holding valve: When the air supply to the control valve fails, it maintains the valve at the opening position before the failure.

4. Solenoid valve: Enables electromagnetic switching of the air path, ensuring the valve remains at the desired safe opening position in the event of a power failure.

5. Handwheel mechanism: Allows manual operation of the valve when the controller of the control system fails.

6. Pneumatic relay: Accelerates the action of the actuator, reducing transmission time.

7. Air filter and pressure reducing valve: Used to purify the air supply and regulate air pressure.

8.

In short, the purpose of accessories is to make the control valve's functions more complete, reasonable, and comprehensive. The company primarily deals in European and American brands, and can source brands from any European country. For example, its key German brands include: BURKERT, DEMAG, HAWE, REXROTH, HYDAC, PILZ relays, FESTO, IFM sensors, E+H, HEIDENHAIN, P+F sensors, SICK, TURCK, HIRSCHMANN industrial switches, Henschler, MURR, SCHMERSAL, SAMSON, and EPRO (a subsidiary of Emerson).

American brands include MOOG, ASCO solenoid valves, MAC solenoid valves, NUMATICS, PARKER pneumatics and hydraulics, and VICKERS.

British brands include: Helon and Norgren. Italian brands OMAL, ATOS, CAMOZZI, UNIVER, and Camozzi.