Instruction manual

Varec, Inc. 87
7532 Radar Tank Gauge
11.6 Performance Characteristics
Note Performance characteristics for devices that can be calibrated in compliance
with OIML R85.
Reference
operating
conditions
According to OIML R85:
• Temperature = -25°C to +55°C (-13°F to +131°F)
• Atmospheric pressure
• Relative humidity (air) = 65% ±15%
• Medium properties: e.g. medium with good reflectivity and calm surface
• Tank diameter: signal beam hits the tank wall only at one side
• No major interference reflections inside the signal beam
Maximum
measured error
Absolute accuracy: better than ±1 mm
Note Free space: 7500 series RTGs typically provide accuracy of ±0.5 mm
(2 sigma value). Depending on the respective national gauging regulations, the
admissible errors after installation of the device on the tank are ±4 mm (OIML,
API)...
Non
repeatability
0.3 mm (1/64”)
Hysteresis 0.3 mm (1/64”)
Long-term drift The long-term drift is within the specified accuracy
Influence of
ambient
temperature
Within the specified accuracy according to OIML R85
Proof of
accuracy of
custody
transfer
versions
The accuracy of each 7500 series RTG is established through a calibration
certificate that records the absolute and relative error at 10 points during the
final test. A Laser Interferometer (Jenaer Messtechnik ZLM 500) with an
absolute accuracy of 0.1 mm is used as a reference for the free space
measurements with 7530/7533. For stilling well measurements with 7530/
7533 RTG(s), an NMI / PTB calibrated tape with an absolute accuracy of 0.25
mm is used. Each 7500 series RTG is delivered with the PTB and NMi type
approval. Additional initial factory verifications for custody applications are
available on demand for radar device 7500 series RTG.
Maximum fill
speed
By the first pass through of measuring range: 100 mm/min., thereafter
unlimited.
Reaction time The reaction time depends on the parameter settings (min. 1 s). In case of fast
level changes, the device needs the reaction time to indicate the new value.
Resolution • digital: 0.1 mm
• analog: 0.03% of measuring range
Settling time Typically 15 sec.