Tank gauges radar

FMCW radar level gauges are the primary tank farm radar devices because of the inherent accuracy. Pulse transmitters are not suitable for tank farm inventory and custody transfer applications. The combination of foam and low-dielectric material can cause errors or provide an insufficient signal strength on the return signal. 

Radar gauges. The use of radar to meastme product levels in storage tanks is one of the most recent techniques. Radar level gauges were developed in the mid-sixties for crude carriers. The majority of these ships were equipped with mechanical float-... 

Radar level gauges do not have moving parts and only an antenna is required in the tank. This results in very low maintenance cost. Although the investments costs are higher when compared to float gauges, the cost of ownership will be considerably... 

Hybrid inventory measurement system. The hybrid inventory measurement system (HIMS) combines the most modern level gauging techniques with hydrostatic tank gauging (Figs. T-13 and T-14). It utilizes an advanced radar or servo level gauge for accurate level measurement, with a smart pressure transmitter (PI) and a temperature measurement instrument. On nonatmospheric tanks a second transmitter for the vapor pressure compensation is required. 

Radar gauges. Radar gauges play an important role in tank gauging (Figs. T-23 and T-24). Their nonintrusive solid-state natiure makes them very attractive. The accuracy of the newest generation radar gauge meets all requirements for custody transfer and legal inventory measurements. 

In summary, a wide range of different tank-gauging instnunents is available. The employed techniques are more complementary than competitive as each measuring principle has its own advantages. See Table T-3. Modem servo and radar gauges have improved considerably. They hardly need any maintenance and can provide trouble-free operation if applied correctly. The possibility of mixed installations with servo, radar, HTG, and HIMS provides optimal flexibility and utilizes the capability of each gauging technique. 

On hard-to-handle services, such as the fluidized-bed level measurement in combustion processes, there is little choice but to use radiation gauges. On slurry and sludge services, d/p units with extended diaphragms eliminate the dead-ended cavity and bring the sensing diaphragm flush with the inner surface of the tank. Other level transmitters that can be considered for hard-to-handle services include the capacitance/RF, laser, radar, sonic, and TDR types. 

Radar level transmitters and gauges use electromagnetic waves, typically in the microwave bands to make a continuous liquid and some solid level measurements. The radar sensor is mounted on the top of the vessel and is aimed down, perpendicular to the liquid surface. Most tank-farm gauges are operated on the FMCW principle (Figure 3.121). Other gauges and transmitters, particularly the lowest-cost units, are operated on the pulse principle. Both principles are fundamentally based on the time of flight from the sensor to the level of the surface to be measured. In the FMCW method, this time of flight is tracked on a carrier wave in the pulse method, it is the echo return. 

The designs of tank farm level detectors include (1) wire-guided float, (2) servo-operated float, (3) surface detector (plumb-bob), (4) radiation backscatter, (5) radar, (6) HTG, and (7) hybrid gauges. Their ranges go up to 60 m (200 ft). 

Radar gauges are also a logical choice for tanks containing hig y viscous products, such as blown asphalts, contaminating products, and liquids that are very turbulent. 

For radar gauges, existing pipes can be used to provide mechanical stability. Circular mode antennas are required when installation on a pipe is foreseen. On high-pressure tanks, installation of an insert with reference pins is recommended. 

Hybrid inventory measurement system. HIMS are also based on the integration of smart pressure transmitters. Modem level gauges, either servo or radar, provide the possibility for direct interfacing to smart pressure transmitters. HEMS opens the ideal route to total tank inventory systems, measuring all tank parameters via... 

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