Field Instrumentation

How To Troubleshoot Level Transmitter Problems and Its Solutions?

What is a Level Transmitter?

A level transmitter is a device used to measure the level of the liquid or solid materials like powder in a container or tank and produce a signal which is directly proportional to the level in storage. It is mainly used in process plants like oil and gas industries, chemicals, power plants, cement industries, chemical industries, etc

Different types of Level Transmitters:

          Based on the measurement type Level transmitter sensor are classified into 2 types they are:

  1. Direct Level Transmitter
  2. Indirect level Transmitter

Most industries use indirect level transmitters since they have both contact (or) non-contact sensors which can easily be applicable based on the purpose.

Differential Pressure Transmitter is used to find the Level Measurement of a  Closed Tank
Closed Tank Level Measurement Using Differential Pressure Transmitter

Based on the working principle level transmitter are of 7 types

  1. Capacitance level transmitter
  2. Hydrostatic level transmitter
  3. Magnetic level transmitter
  4. Radar fill level transmitter
  5. Ultrasonic level transmitter
  6. Guided microwave level transmitter
  7. Liquid level transmitter

The level of filling can be measured by:  

VOLUME = HEIGHT X AREA

Based on the performance of the level transmitter, these types cause different problems in their measurement:

What are the various problems which will occur in Level Transmitters?

Problem and solution have been tabulated for different types of transmitters:

Problems arise in Capacitance Level Transmitter:

LEVEL TRANSMITTERPROBLEMSOLUTION
Capacitance Level TransmitterDrift change in the temperaturea. Temperature compensation sensor can be used to get the output
b. Sensors that can read actual output even at the temperature drift can be used
Tank Thickness causes various sensing measurementSensor with high resolution can be used to detect the absolute value of measurement in the tank
High Viscosity fluid creates errors in sensingThe Inner wall of the tank is to be made smooth and slippery so that fluid can be easily drained to obtain an accurate measurement
Salt Concentration in the liquidSalt Filtration is done by removing contamination below 0.5g/L for accurate output
Magnetic Level TransmitterDue to improper welding in the measurement leg causes errorRe-welding is to be done in the measurement by isolation and again connected to get the float output and reading obtained in the sensor
Radar Fill Level TransmitterContamination of Antenna due to the external source like moisture, dust, etc.To avoid the spill level the antenna is to be cleaned regularly
Interference echo signal received due to reflection of the sound wave ionized and also due to abnormal weather conditionThe use of sun strobes and soundproofing in the signal receiver can avoid the interference echo
Radar installation in an inappropriate locationRadar to be installed at the signal receiving location with no disturbance
Parameter value like time constant value causes an errorTime constant value to be set stable to obtain the output in the radar
Ultrasonic Level TransmitterStirring causes error outputInstallation of the static pipes improves the flow and gives accurate output
The formation of the foam-like dry foam, wet foam, and neutral foam affects sensingRapid flow at high pressure without the formation of the foam helps sense the signal
Steam Formation due to high temperature in the working environmentImplementation of the static pipe in the vessel to avoid the false output
Blind Area available for more high levels of filling or too small levels of fillingThe flow of liquid to be done to the high level at the set point that sensor can able to detect the level
A rapid increase in the temperature decreases the pressure level, and generates false outputTemperature level to be monitored periodically to measure accurate level by a sensor
High vapourised liquid affects the sound speed and soft material affects the sensing range of the materialThe high sensing element can be used to avoid this type of error
The size of the target, poor sound reflection, and width of the sensing path affect the sensing of the signalAccurate analysis of the target and signal amplification with a wider sensing beam provides the accurate output
Guided Microwave Level TransmitterProbe connection causes error in the measurementUsing a coaxial probe can help to detect the resultant output in the transmitter
Foam with high conductive causes errorMaterial with high conductivity to be avoided in the formation of foam during flow provide exact output
Disturbing objects near the probe creates errors in the output signalObjects that create disturbance to be avoided or alternative for signal reflection to be implemented to get the output
Problems and Solutions of Various Level Transmitters

TEMPERATURE PROBLEM:-

A change in the temperature may cause an error reading in the capacitance level transmitter. Due to a change in the temperature drift, the output obtained is false.

SOLUTION FOR TEMPERATURE ISSUE-Temperature compensation sensor can be used along with the capacitance level transmitter to compensate for the temperature errors.

THICKNESS PROBLEM:-

The thickness of the tank cause change in the signal of the liquid and it shows too small value when there is no storage of liquid in the tank.

SOLUTION FOR THICKNESS PROBLEM:-– Sensors with high-resolution detection can be used that can detect the absolute measurement even at a too-small level of liquid stored in the tank.

VISCOSITY PROBLEM-

The viscosity of the fluid may cause false reading in the transmitter. High viscosity fluid takes time to provide level measurement with accuracy.

SOLUTION FOR VISCOSITY PROBLEM-– To avoid the problem caused due to the viscosity of the fluid, the tank’s inner layer is made smooth and slippery so that the high viscosity fluid can be easily drained to measure the level in the transmitter.

SALT CONCENTRATION PROBLEM:-

Some Liquid contains salt concentration that shows inaccuracy. Due to the higher salt concentration in the liquid, the sensor shows low accuracy of measurement.

SOLUTION FOR SALT CONCENTRATION PROBLEM:-Filtration of the salty liquid to be done and contamination point to be below 0.5g/L allowed in the tank for accurate measurement in the level transmitter

Problems arise in Magnetic Level Transmitter:

WELDING PROBLEM:-

Due to improper welding in the magnetic level measurement the float fails to sense the level, this leads to providing false measurement in the transmitter.

SOLUTION FOR WELDING PROBLEM:- Rewelding in the damaged float to be done and connected to the sensor, the accurate level of measurement can be obtained in the sensor.

Problems arise in Radar fill Level Transmitter:

CONTAMINATION PROBLEM:-

The contamination or damage in Antenna causes the radar sensor to show the fault.

SOLUTION FOR CONTAMINATION PROBLEM:-To avoid the spill level of the radar, the radar is to be cleaned regularly during periodic maintenance.

ECHO PROBLEM:-

Due to reflection, the sound waves get ionized in the atmosphere, and interference echo signals are received on the radar. Sometimes it may occur due to changes in the weather condition.

SOLUTION FOR ECHO PROBLEM:- Sound proofing and sun strobes can be implemented to reduce the interference echo noise signal in the radar.

LOCATION PROBLEM:-

Installation of the radar in an inappropriate location affects the radar to receive the signal.

SOLUTION FOR LOCATION PROBLEM:- Radar to be installed in the location where the signal can be received without any disturbance.

TIME CONSTANT PROBLEM:-

If the parameter value for the radar signal is like a time constant, changes in the level of measurement affect the radar sensor.

SOLUTION FOR TIME CONSTANT PROBLEM:- The time constant value should be set to the stable parameter value to sense the signal in the radar

Problems arise in Ultrasonic Level Transmitter:

STIRRING PROBLEM:-

Stirring occurs due to the flow in the ultrasonic level transmitter causing the error output in the ultrasonic level transmitter.

SOLUTION FOR STIRRING PROBLEM:- Static pipes can be used to regularise the flow, which helps to measure the level in the transmitter.

FOAM PROBLEM:-

The formation of the foam in the container can affects the ultrasonic level transmitter to measure. The foam may be in the form of wet, dry, or neutral foam. This foam distracts the sensor to sense the level of measurement.

SOLUTION FOR FOAM PROBLEM:- While the flow of the fluid is done inside the vessel at high pressure it should be monitored in rapid flow to avoid the formation of the foam in a vessel so that the level can be measured accurately in the ultrasonic transmitter.

STEAM PROBLEM:-

Since the working environment temperature is high, the flow of liquid inside the vessel converts into steam due to the high temperature. This steam makes them float sense before attaining the filling level and output is generated as false output in the ultrasonic level transmitter.

SOLUTION FOR STEAM PROBLEM:-Static flow pipe can be connected in the chamber to attain the exact value of measurement by avoiding the steam vaporization in the tank

BLIND AREA PROBLEM:–

A blind area will be available in the vessel if the level of the liquid is high or small, so the ultrasonic level transmitter cannot able to detect the measurement of storage.

SOLUTION FOR BLIND AREA PROBLEM:– To avoid the binding area, the liquid is stored at a high level without reaching the blind area. This helps the ultrasonic sensor sense the level of the measurement.

MATERIAL PROBLEM:-

Ultrasonic level transmitter not sensing the material chosen for storage. High vapourised liquid affects the sound speed and will not generate accurate reading, similarly, soft material like powder or foamy surfaces reduces the sensing range.

SOLUTION FOR MATERIAL PROBLEM:- The above problem can be avoided by preventing the vaporization of the material, similarly, high sensing material can be used for sensing the level of the measurement in the transmitter.

TARGET & WIDTH PROBLEM:-

Factors like the size of the target, poor sound reflection, and width of the sensing path also affect the level of the measurement in the ultrasonic transmitter.

SOLUTION FOR TARGET & WIDTH PROBLEM:- Accurate analysis of the target, and signal amplification with a wider sensing beam will help to measure the accurate level.

Problems arise in Guided microwave Level Transmitters:

 PROBE PROBLEM:-    

Probe connected to the level transmitter causes error output due to connection fault, length, and mounting restrictions. This generates false output in the guided microwave level transmitter.

SOLUTION FOR  PROBE PROBLEM:-The best solution for this error is to use of the coaxial probe in their connection which doesn’t have direct contact with the metallic objects which prevents the error and provides the absolute output in the guided microwave level transmitter.

CONDUCTIVITY PROBLEM:-

A guided microwave level transmitter is used in foam measurement. Foam can be in the form of air, wet, high or low dielectric medium causes the error. If the foam is less conductive, the signal penetrates through the foam, if it is highly conductive it shows error output.

SOLUTION FOR CONDUCTIVITY PROBLEM:- Formation of the foam to be avoided during the flow of the fluid inside the vessel which creates high conductivity, this helps the sensor to sense the signal and provide accurate output in the guided microwave level transmitter.

DISTRACTION PROBLEM:-

Disturbing objects close to the probe creates a distraction in sensing the signal in the level transmitter.

SOLUTION FOR DISTRACTION PROBLEM:- The objects that create disturbance to the probe to isolated from the connection, so that the sensor can be easily able to sense the signal and measure the level of point and provide output in the guided microwave level transmitter.

Related posts

What is a pneumatic cylinder? What are the types of pneumatic cylinder

Ashlin

What is a smart sensor and how is it different from a normal sensor

Ashlin

What are the differences between transducer and transmitter?

Mahesh
Follow Us on LinkdIn