“การเลือก อุปกรณ์วัด และ ควบคุม อัตราการไหล โดยใช้ Paddle Wheel, Paddle และ Oval Gear ”

Last updated: Oct 15, 2020  |  72 จำนวนผู้เข้าชม  |  Article

การเลือก อุปกรณ์วัด และ ควบคุม อัตราการไหล โดยใช้ Paddle Wheel, Paddle และ Oval Gear

 

FLOW measurement การวัดและควบคุมอัตราการไหล ของ ของไหล

Flow Measuring Principles

Paddle wheel sensors

วัสดุที่ใช้สำหรับ Paddle wheel (พลาสติกหรือสแตนเลสสตีล) หรือบน พื้นฐานของการตรวจจับ / ประเมินสัญญาณ (เซ็นเซอร์คอยล์, เซ็นเซอร์คอยล์ HT, เซ็นเซอร์ฮอลล์หรือเซ็นเซอร์ออปติคัล) ผลลัพธ์นี้แตกต่างกันสี่ประการ

1. Plastic paddle wheel (PVDF or PP) with inductive detection and pulse output

A PVDF or PP paddle wheel with four molded permanent magnets in the arms rotates on a precision, wear resistant ceramic spindle and two ceramic bearings. A Hall sensor detects the magnetic field of the rotating paddle wheel is placed outside of the fluid area. Two output signals are generated per revolution and the frequency changes proportionally with the speed of rotation of the paddle wheel. An integrated electronics board converts this signal to a square-wave frequency signal.

2. Plastic paddle wheel (PVDF or PP) with inductive detection and sinusoidal output

A PVDF or PP paddle wheel with four molded permanent magnets in the arms rotates on a precision, wear resistant ceramic spindle and two ceramic bearings.

A coil with a ferrite core, detecting the magnetic field of the rotating paddle wheel, is placed outside of the fluid area. The frequency and voltage change in proportion to the rotational speed of the paddle wheel and two positive signals are generated per re-volution. The rotation of the paddle wheel generates a sinusoidal voltage signal in the coil proportional to the flow rate. This sensor is two-wire and requires no additional auxiliary energy supply. A connected, battery operated display unit allows operation independent of mains voltage.

3. Plastic paddle wheel (PVDF) with optical detection and pulse output

The paddle wheel is made of PVDF material and the spindle and two bearings are made of wear-resistant ceramic material (Al2O3). Two infrared transmitters (IR) and receivers are placed in the electronics housing outside of the medium area, separated by plastic which allows infrared radiation to pass through it. The rotation of the paddle wheel is detected with these IR diodes and the integrated electronics converts the reflected IR-Signal to a square wave frequency signal, proportional to the flow rate. This optical method allows the flow rate to be detected in media with ferromagnetic particles and to detect the direction of the flow

4. Stainless steel paddle wheel with inductive detection and pulse output

This paddle wheel consists of stainless steel with very low ferromagnetic characteristic. The spindle is made of a high-tech ceramic or stainless steel and the bearing is made of PEEK or ceramic. Inside the top-mounted electronics is a HT coil with permanent magnets and electronics which converts the coil signal into a square wave frequency signal proportional to the flow rate. The frequency changes in proportion to the speed of rotation of the paddle wheel. Two positive output signals are generated per revolution. This method is particularly used for media with temperatures up to 160°C (320°F). Ferromagnetic particles and contaminants in the fluid do not restrict the range of application.

Paddle with Magnetic Detection and Switch output

 

Plastic paddle with magnetic detection and switch output

A permanent magnet is integrated into a paddle. The paddle is able to turn on a stainless steel spindle in the flow cross-section and is in vertical position if there is no flow. A reed contact is positioned above the paddle outside the medium area in the electronics housing. If a specific flow velocity is exceeded, the paddle is deflected in flow direction and switches the reed contact. The switching point can be set for increasing and decreasing flow velocities by means of an adjusting screw. The devices are available in the following versions: ––Normally open (NO). The flow closes the contact. ––Normally closed (NC). The flow opens the contact.

Oval Gear with Inductive Detection and Pulse output

 

Volumetric flow measuring: oval gear withinductive detection and pulse output

Two toothed oval rotors, mounted perpendicular to the flow direction in a special housing, are forced to rotate by a flowing fluid. Each rotor transmits fluid from inlet to outlet and forms a closed compartment when its major axis is aligned with the main flow direction. The volume passed per revolution of each rotor is four times the volume between the rotor and the oval housing when the rotor is confining liquid. Two small permanent magnets positioned in one of the oval gears are used to detect the rotary movement. A Hall sensor which detects the magnetic field of the oval gear and generates two square-wave output signals is placed outside of the medium area in an electronics housing. The number of pulses is directly proportional to the number of chamber volumes pumped and therefore making this method particularly suitable for flow measurement of viscous media even at high pressure.

 

 

DATA SHEET DOWNLOADS

 Type 8010 - Inline Paddle Wheel Flow Switch
 Type SE11 - Paddle wheel transmitter with magnetic measuring principle for flow measurement
 Type 8012 - Flowmeter with paddle wheel for continuous flow measurement
 Type 8030Ex - Inline flowmeter for continuous measurements
 Type 8030 HT - Inline flowmeter for continuous measurements
 Type 8030 - Inline flowmeter for continuous measurements
 Type 8032 - Flowmeter/Threshold detector with paddle wheel
 Type 8035 - Inline flowmeter or batch controller with paddle wheel
 Type 8036 - INLINE flowmeter with paddle wheel, ELEMENT design
 Type 8039 - Inline Paddle Wheel Flowmeter, optical signal detection
 Type 8020 - Insertion flowmeter with paddle wheel for continuous flow measurement
 Type 8025 - Insertion flowmeter or batch controller with paddle wheel and flow transmitter or remote batch controller
 Type 8026 - Insertion flowmeter with paddle wheel, ELEMENT design
 Type 8031 - Flow Sensor for low-flow measurement
 Type 8077 - Flowmeter with oval rotors
 Type SE30 - Transmitter for Inline sensor-fitting + Type S077 - Positive displacement sensor fitting for continuous flow measurement
 Type SE32 - Transmitter for Inline sensor-fitting + Type S077 - Positive displacement sensor fitting for continuous flow measurement
 Type SE35 - Transmitter or batch controller for Inline sensor-fitting + Type S077 - Positive displacement sensor fitting for continuous flow measurement
 Type SE36 - ELEMENT transmitter for Inline sensor fitting + Type S077 - Positive displacement sensor fitting for continuous flow measurement
 Type SE30 - Transmitter for Inline sensor-fitting + Type S077 - Positive displacement sensor fitting for continuous flow measurement

 

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