A flow control valve is a device used in process industry, which has function similar to a water tap at our homes. In a water tap, the quantity of water flow is regulated by rotating the handle of the tap, either clockwise or anti-clockwise. The quantity of water discharge is decided by the size of the tap. For larger sized tap, more water flows for the same opening, compared to a small tap. In flow control valve the operation of opening and closing is done remotely by pneumatic air pressure, in association with a control valve. The air pressure for opening and closing is used because, the fluid may be toxic or inflammable, or shear muscle power needed to control discharge of large quantities of fluid. Moreover I-P converter, which is used to open or close the flow control valve, can be remotely operated. Now there is a need to study two aspects of Flow Control Valve. 1) How to open and close a flow control valve under controlled condition. 2) The rate of discharge of fluid under consideration. The scope of this module is restricted only to the study of opening and closing and not the fluid flow. The full potential of the flow control valve is experimented in FLOW AND LEVEL CONTROL TRAINER, when water is used as medium or PRESSURE CONTROL TRAINER, where air is used as medium of discharge. The control valve dynamics involve, the response time of the control valve from the time a control valve reaches a desired position. This time of actuation can be from fully closed condition to the fully open condition, or from and to a desired position of the stem. 2) Hysterisis study of a control valve. It is possible to position the stem of the control valve within the range of valve movement. It is possible to position the stem of the control valve by applying air pressure (in the range of 3 to 15 PSI), from fully closed position (0% opening), to the fully open (100% opening) position. Due to mechanical inertia of the control valve, the stem position is different for the same air pressure during upward travel and downward travel. This difference in stem positioning contributes to the hysterisis. Smaller the difference, the better is the control valve. By this experiment we now study, how good or how bad is the control valve. The study of flow control valve consists of single seated low flow control valve. The instrument is supplied along with necessary Electro pneumatic converter; current transmitter, current meter, DC power supply, and interface electronics, pneumatic connections by FESTO make quick couplings. Compressed air at 5 Kg/cm2 must be supplied by the user. Control valve position feedback is available for Data Acquisition purposes. Specifications:
a) Control Value: - Fluid: Water
- Body form: Globe-2-Way
- Size body/port/Cv: 1/2"- 1/4" - 2.0Gpm
- End connection / rating: Flanged RF - ANSI -150#
- Body material: CCS
- Trim form / Material: Contoured / SS304
- Flow chart/Direction: Linear / Under
- Actuator type: Diaphragm
- Control Signal: 0.2 - 1.0 Kg/cm2
- Valve action: Air to open
- Total stem travel: 18mm
- Equal percentage contoured low flow control valve.
- Input: 3 to 15 PSI air pressure.
- Two current meters to monitor a) input to I-P converter, b) Valve position.
- Filter line regulation unit.
- Interface electronics suitable for Data Acquisition instrument, Model DAS-1.
- 5kg/cm2 compressed air to be supplied by the user.
- FESTO make quick couplings.
- Electronics include, power supplies, Instrumentation amplifiers.
- Table top model.
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