Types of reservoir level measurement systems
Types of Liquid Level Gauges: Many types of tank metering systems are sufficiently reliable in gasoline metering applications, but biofuels have raised issues that could be more corrupt. Dip tapes, despite the disproportionate extent of tank measurements, are still a very popular method of measuring tank surface and are used in the initial installation and calibration of many automatic tank measuring systems. (Liquid level gauge)
Types of liquid level gauges
The main types of tank level detection used in the gasoline storage industry are:
- Floating level gauge
- Radar level gauge
- Babylonian system
- Level tracker (plumb-bob) gauge
- Unconnected, conductive and cellular meters.
Floating level gauge
The buoyancy gauge and servo radar are currently the most common level measurement systems used at gasoline storage sites. Gasoline has a detrimental effect on buoyancy gauge systems, as long as care is taken to ensure that the right materials are used for sealing and washers. However, the same cannot be said about the impact of biofuels. These devices can be damaged due to some corrosive biofuel additives. This can be problematic because some tanks may use biofuels and gasoline to store fuel at different points in their lives. This change may not be recorded in the management of the company’s change processes and therefore may not be subject to impact analysis or risk assessment.
The main types of level switches are:
- Lollipop switch
- Lollipop switch
- Magnetic Loll Switch
- Light switch
- Float switch switch
Floating level gauge
The most common surface switches at oil storage sites are magnetic switches. With the evolution of production techniques, it is possible to produce magnetic surface measuring components on a larger physical scale. Until recently, despite being very accurate, they did not have the proper measurement methods for transferring custody at filling stations. Manufacturers of surface measuring systems have now begun to develop and market “hybrid” measuring systems. Examples of these systems are hydrostatic tank sensing systems (HTG) that use intelligent sensors, and a system that encloses radar and capacitive tank sensing technology.
Deep level gauge
A calibrated bar is reduced by the weight attached to the tank until the weight contacts the bottom of the tank. The operator then collects the tape, while carefully stopping on the tape that has dried, and pulls it out of the wet tank. It provides a depth measurement in millimeters or inches. With the known dimensions of the tank, the volume of liquid available can be calculated. It is used in setting up automated systems such as radar and servo level systems
Known problems
The accuracy achieved depends largely on the experience and skill of the operator
Maintenance
The tape should be calibrated and inspected before use for peeling
Accuracy
Potential for achieving 10 mm pounds
Level gauge
The wire is fixed at the top and bottom of the tank and is used as a guide for the float. The float consists of an induction inductor converter supplied by a wire. In short distances, the primary connection is disconnected and the secondary induction connection is obtained from the converter to the conductor on the wire. The measurement is made by conductors placed at specified intervals on the wire, which produces a gray coded word. This is one of the cheapest level measurement systems available and is still commonly used.
Known problems
- It can experience hanging strips
- Material construction can impede the free movement of the float (can not be used in dirty applications)
Uses
- “Clear” measurement programs
- Measuring the level of custody transfer
Maintenance
A high level of maintenance is required due to the number of moving parts.
Accuracy
Low accuracy
Float level meter
Works with fluid displacement for continuous measurement. A displacement is continuously measured inside the tank. By changing the level (liquid level gauge), the system always aims to maintain the displacement in equilibrium, which produces the level measurement.
Known problems
- Cannot be used in dirty applications
- Ferrous materials can negatively affect the performance of the system
Consumes
- Transfer of custody
- Inventory management
- Measuring problem petrochemicals
Maintenance
A high level of maintenance is required due to the number of moving parts
Accuracy
Up to +/- 5 mm
The weight of the “pipeline” comes down from the sensor unit, which is fixed to the top of the tank as long as the weight is in contact with the surface of the material. The weight is then added to the sensor unit and the line is measured. The resulting measurement is then used to calculate the level of material in the tank. It has been suggested by industry experts that both system designers and manufacturers should consider this method for measuring the tank, which is no longer needed because of the different levels of reliability and accuracy of measurement and dependent methods require high maintenance. .
Known problems
- The weight of the piping can be broken down into a sensor unit
Consumes
- Periodic level measurements only
Maintenance
A high level of maintenance is required due to the number of moving parts
Accuracy
- Maintenance dependent
- Not comparable to servo or radar level measurements
Radioactive Level Gauge
It uses a radioactive source as a transmitter and a radiation detector to determine the level of material in the container. This technology is not commonly found in the gasoline (fuel) storage industry. However, with very high accuracy, comparable accuracy can be achieved with radar or head gauges, both of which have less maintenance overhead.
Known problems
- it is very expensive
Consumes
Preferred measuring system for highly corrosive materials, which reduces the measurement quality of other surface measuring systems.
Maintenance
The maintenance requirements of this system are low compared to mechanical options. However, there may be other inspection obligations in connection with the licensing of the radioactive source.
Accuracy
very carefully
Radar level gauge
Uses K or X band electromagnetic waves for continuous surface monitoring. Communication using frequency modulation carrier wave (FMCW). Pulse width modulation is also used by some types of this system. Currently, this is one of the most popular level measurement methods used in gasoline storage. It can be used in countless environments, completely safe, explosion-proof, non-irritating (electric, but not flammable).
Known problems
You can use processing equipment, ship stirrer, etc.
Consumes
- Inventory control
- process control
- Transfer of custody
Maintenance
Maintenance requirements are low compared to mechanical options because they have much fewer moving parts. However, electronic equipment for monitoring component aging does not reduce measurement
Accuracy
Very accurate but easily affected by external interference. Maximum +/- 3 mm
Gajing tank radar
This method has a probe, commonly known as a “waveguide”, located in a container that is used to transmit measurements by transmitting a periodic pulse. There are currently a number of different reception methods that make sense of the reflected signal. Currently accepted and accepted methods are: Amplitude Timing Reflection (TDR) – there is less power with higher efficiency, DC measurement methods are also available. these are:
- Guided Wave Radar (GWR). Based on TDR
- Phase difference sensor (PDS). Determines the amount of change in the phase angle of the material in the container.
Currently, this is one of the most popular level measurement methods (liquid level gauges) used in gasoline storage. It can be used in countless environments, completely safe, explosion-proof, non-irritating (electric, but not flammable).
Known problems
- It can only accurately measure the surface in materials with dielectric values greater than 1.4 (for example, it does not do well with water-based materials).
Consumes
- Inventory Control
- Process Control
- Custody Transfer
Maintenance
Maintenance requirements are low compared to mechanical options because they have much fewer moving parts. However, electronic equipment for monitoring component aging does not reduce measurement
Accuracy
Accuracy depends on the dielectric constant (permissibility of the material). Maximum +/- 2 mm
Capacitive level gauge
Capacitive level gauge Capacitor configuration is made, using sensor probe and metal tank wall as capacitor plates. The material in the tank enters the area between the two plates and causes the amount of capacity measured to change as the surface of the tank changes. A manufacturer has developed a new level measurement system that uses capacitive and radar level measurement technologies together and is referred to as hybrid level sensors.
Known problems
- It is not possible to measure the point at which stored material changes. For example, liquid level gauges, gasoline water boundary can not be determined
Consumes
- Inventory Control
- Process Control
- Custody Transfer
Maintenance
Maintenance requirements are low compared to mechanical options because they have much fewer moving parts. However, electronic equipment for monitoring component aging does not reduce measurement
Accuracy
- Distance measurement
Hydrostatic Level Gauge (HTG)
The hydrostatic level gauge works by placing pressure sensors in different parts of the tank. These pressure readings are used to calculate the mass of matter in the tank. HTC can be implemented using a pressure difference sensor that measurement errors can be compensated when using two separate sensors. This is a kind of differential tank.
Known problems
Inserting sensors can introduce an error which in turn can lead to incorrect level measurement.
Consumes
- (Clean liquid measurement (atmospheric & pressurized
- (Hard to handle fluid measurement (atmospheric & pressurized
- Bi-phase material
- Cryogenic material
- Boiling material
Maintenance
Theoretically, maintenance is not required in these systems. In reality, however, inspection and replacement of pressure and temperature sensors will be required. It is necessary to minimize material deposits from the sensor surface
Accuracy
- Low accuracy using a single pressure sensor
- It is very accurate when using two or more pressure sensors
Ultrasonic level gauge
The ultrasonic level gauge of this sensor emits an audio frequency between 20kHz and 200kHz. This release is then returned from the liquid surface (liquid level gauge) to a detector. The time required between the transmission of a signal and the reception of a reflected signal is a measurement of the liquid level in the tank. This is not usually seen in the gasoline storage industry. It is more popular in the water industry
Known problems
- Measurement accuracy is affected by the placement of the ultrasonic transducer.
- This type of measurement system is prone to rusting
Consumes
This method of level measurement is rarely used due to the perceived inaccuracy in the gasoline storage industry
Accuracy
Low
Babylonian system
The Babylonian system passes a constant velocity of air through a tube immersed in a liquid. Some air escapes through the tube outlet. The pressure in the pipe is proportional to the depth and density of the liquid at the outlet of the pipe. One advantage of this method is that the control equipment and instruments can be placed away from the physical storage tanks, which provides you with some of the necessary items and, if necessary, all the necessary items for the previous equipment.
Known problems
- Not considered accurate enough to transfer custody
- Requires specialized knowledge to maintain
Consumes
- Used in open tanks under atmospheric pressure
Maintenance
Maintenance activity requires special specialists
Accuracy
Up to +/- 10 mm of level
Gijing tank hybrid
The hybrid tank gauge measures volume, temperature and density in specific settings. Similar to HTG systems. This form of tank gauge is still evolving. Hence, further research is needed on the principles surrounding it
Temperature difference level gauge
Temperature difference level meter In this method, thermal differential monitoring is used through two RTDs. RTD measures the temperature of the liquid in its vicinity. The second RTD is self-heating and rises to a predefined temperature. The read temperature comparison creates a differential. Using the knowledge of the thermal properties of the liquid, it can be determined whether the liquid is present at the sensor point in the tank. If the differential is out of range, it is assumed that the RTD is in gas, not liquid, hence a surface detection. This is not a standard level measurement (liquid level gauge) common in the gasoline storage industry.
Known problems
- This type of measurement system can not be used if the entry of heat into the stored product destroys it or endangers its chemical stability.
Consumes
- To determine if the tank level is below the threshold
- Control fluid flow in or out of tank vessels
Maintenance
Due to the lack of moving parts, the maintenance regime will be similar to what is required in radar-based systems.
Accuracy
It can achieve complete measurements between 0.1% and 5%
Slip tube gauging
Rotary Method
The head is used to extract the contents of the tank. The head works until the steam is drained from the bleeding connection. By detecting steam, a handle is rotated that rotates the assembly of a slip tube. This continues until the liquid begins to drain into the tube.
Vertical Method
The slip pipe goes down into the tank. After contact, the liquid instead of steam will begin to bleed from the cap assembly. The surface through which the liquid enters the tube can communicate with the surface of the tank
Known problems
This method of measurement requires the amount of material stored in the atmosphere. With gasoline, such a measure raises environmental issues
Consumes
This level measurement method is rarely used in the gasoline storage industry.
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