About Temperature and Free Water Level for Tank Gauging

Get high accuracy temperature data for net volume calculations in inventory and custody transfer applications.

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High Accuracy Temperature Measurements for Custody Transfer

The ultra-stable Rosemount™ 2240S Multi-input Temperature Transmitter is approved for demanding custody transfer applications. The Rosemount 2240S transmitter has a temperature conversion accuracy of ±0.05 °C (±0.09 °F). It can connect up to 16 three- or four-wire temperature spot elements and an integrated water level sensor.

Calibrated four-wire multiple spot sensors can be used for highest precision volume measurement.

How it Works

Rosemount 565/566/765 sensors measure with one to sixteen Pt-100 spot elements at different heights to provide a tank temperature profile and average temperature. Typically ±0.025 °C (±0.045 °F) accuracy is achieved with a calibrated four-wire sensor. The Rosemount 566 is designed for cryogenic applications. Each sensor is connected either directly to the Rosemount 2240S temperature transmitter or via a cable. Sensor accessories include weights and thermowells.

The Rosemount 765 sensor measures free water level below the oil surface and provides an input for online net inventory calculations. It is available in open and closed versions. The open version is suitable for crude oil and the closed version is suitable for lighter fuels such as diesel. It is equipped with a multiple spot temperature sensor, with the possibility of having one element installed inside the water level probe allowing measurements at low levels.

The Rosemount 566 sensor is equipped with type A elements, suitable for low temperatures such as measurements in LNG tanks. Spot elements are encapsulated in a stainless steel tube, filled with Argon gas to prevent condensation of water inside the sensor. If the sensor is used in pressurized tanks, it must be protected by a thermowell with ambient pressure inside. 

Pt-100 deviations can be eliminated with computer controlled calibration of up to 16 elements, 4-wire option. Each element is compared against a very precise reference element in one or several temperature points.

The Callendar–Van Dusen constants are calculated, included in a certificate, and entered into the Rosemount 2240S Temperature Transmitter via Rosemount TankMaster. This results in approximately ten times better accuracy, 0.025 °C (0.045 °F).

Single point temperature measurement is used in applications with medium accuracy requirements on volume measurements, or when it is not possible to use a multiple spot temperature sensor due to installation restrictions (e.g. an LPG tank with thermowell). The Rosemount 644 Temperature Transmitter can be ordered with a Rosemount 65, 68 or 214C Single Point Temperature Sensor.


See how New York Terminals accomplished safe operations

To stay competitive in challenging markets tank terminals need to minimize manual work, efficiently use tank capacity and maximize transfer rates, without jeopardizing safety.

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