As many of you know, I have written this book which is being published by North Light Art Books, Cincinnati, Ohio. To give you a flavor of the book: TABLE OF CONTENTS Chapter 1 Painting Ma…Full description
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Alfa Laval Marine & Power AB SE - 147 80 Tumba Sweden
The WT 200/MT 50 water transducer is used to monitor the water content in the processed oil leaving a separator. The signal from the water transducer is processed in the EPC program unit, and appropriate action is initiated, depending on the status in the separation system.
1.2
Design
The water transducer consists a housing (5), a concentric electrode (4), and a electrical conn.box fitted to the housing. The box contains an oscillator unit (2), a test circuit board (1) and connections. The electrode is insulated (3) from the housing and form a circular capacitor. The transducer is mounted in the oil pipe by flanges on the outer pipe, and the full oil flow passes through the capacitor.
1.3
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Test circuit board Oscillator unit Insulators Electrode Transducer housing
Working Principle
The EPC supplies direct current (DC) to the transducer. The oscillator converts the DC to a high frequency alternating current (AC) which is fed to the capacitor. Changes of capacitance are detected and continuously transmitted to and interpreted by the EPC. 1818051-02
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1 Function Description
WT 200/MT 50
The capacitance varies with the dielectric constant of the liquid flowing through it. As the water content in the oil increases, so does the dielectric constant, and consequently its capacitance. There is a large difference between the dielectric constant of water and oil. Hence fluctuations in dielectric constant is a very sensitive measure of changes in water content. Both free and emulsified water contamination is measured.
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Fault Finding
The EPC monitor the signal from the transducer and gives alarm if there is a fault. The fault finding is described in the section “Alarms and Fault Finding”.
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2 Fault Finding
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WT 200/MT 50
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Maintenance
3.1
Cleaning the Water Transducer
Dirt that has klogged between the inner and outer pipe of the transducer may cause high transducer value. If this happens, the transducer has to be opened and cleaned.
1. Remove the electrode and electrical connection box carefully from the pipe system, preferably whithout disconnecting the signal cable.
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2. Clean the electrode and housing with suitable detergent. After cleaning, remove any detergent with a damp cloth.
3. Before remounting the transducer, check that no solids or other matter that can cause short-circuit is stuck between the transducer electrode and housing.
3.2
Replacing the Oscillator Unit
The oscillator unit must be replaced when the EPC detects a transducer fault and the voltage test indicates faulty oscillator unit (see Alarms and Fault Finding).
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The oscillator unit with test circuit board are replaced together as a complete unit.
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3 Maintenance
WT 200/MT 50
1. Disconnect the cables from the oscillator terminals. 2. Loosen the centre screw and lift out the complete unit. 3. Assemble the complete oscillator spare part unit and connect the cables to the terminals. 4. Fill in the report form and return it with the faulty oscillator unit to Alfa Laval.
3.3
Checking the Transducer Value
If the transducer is connected to an EPC-400, or an EPC-50, the EPC can display the transducer value. The value should be 120 – 130 for the transducer in air.
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Technical Data
4.1
Specification
Body Media
Mineral oil
Media temperature
Max. 110°C
Max. working pressure
600 kPa (6 bar)
Max. testing pressure
1000 kPa (10 bar)
Material Body
Pressure vessel steel
Electrode
Stainless steel
O-rings
Viton
Insulators
PTFE
Flanges according to DIN 2633 and JIS B2213 Ref. 1764185 Rev. 3
