The nozzle and flapper mechanism is a displacement type detector that converts mechanical movement into a pressure signal, covering the nozzle hole with a flat plate called flapper . This limits the flow of the nozzle fluid and generates a pressure signal.
This is a widely used mechanical way to create high gain fluidic amplifiers. In industrial control systems, they play an important part in the development of Pneumatic PID controllers and are still widely used today in pneumatic and hydraulic control systems and instrumentation.
Video Nozzle and flapper
Principle of operation
The operating principle utilizes a high gain effect when the flapper plate is placed at a small distance from a small pressurized nozzle that emits fluid.
The example shown is pneumatic. At sub-millimeter distances the small movements of flapper plates result in major changes in flow. The nozzle is fed from a room which in turn is fed by a restriction, so flow changes produce a change in the pressure of space. The nozzle diameter must be greater than the restriction orifice to work. The high gain of the open-loop mechanism can be linear using pressure feedback bellows on the flapper to create a balance-style system with linear output. Zero "direct" 0.2 bar or 3 psi is set by the bias spring ensuring that the device is working in its linear region.
The industry standard ranges are either 3-15 psi (US), or 0.2 - 1.0 bar (metric), typically used in pneumatic PID controllers, valve position servomechanisms and balance balance transducers.
Maps Nozzle and flapper
Apps
Nozzle and flapper in pneumatic control are simple low maintenance devices that operate well in harsh industrial environments, and do not present the risk of explosions in hazardous atmospheres. They are industrial controllers for decades until the emergence of a reliable and reliable high-gain electronic amplifier. However they are still used extensively for field devices such as control valve positioners, and I for P and P for my converters.
The proportional control scheme is shown here.
The set point is transmitted through the flapper plate through the fulcrum to close the hole and increase the space pressure. The feedback buoy refuses and the output signal enters the control valve open with increasing actuator pressure. As the flow increases, the bellows process value negates the point bellows set until the equilibrium is reached. This will be a value below the set point, because there must always be an error to generate the output. The addition of an integral bell or "reset" will remove this error.
Prinsip ini juga digunakan dalam kontrol sistem hidraulik.
Referensi
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Arthur Akers; Max Gassman; Richard Smith (2006). "7.4 Flapper Nozzle Valve". Analisis Sistem Daya Hidraulik . Tekan CRC. pp. 182-184. ISBN: 978-1-4200-1458-7. - S K Singh (2003). "13.6 Sistem kontrol proses otomatis". Instrumentasi Industri dan Kontrol 2e . Tata McGraw-Hill Education. pp. 481-495. ISBN: 978-0070678200.
Source of the article : Wikipedia
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