Milltronics airanger XPL plus, Instruction Manual, Page: 85 / 114

7ML19981AN02 AiRanger XPL Plus – INSTRUCTION MANUAL Page 81
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homogeneous (well mixed), at a fixed temperature, and consistent vapour pressure, by
performing a Sound Velocity Calibration (P651).
The XPL Plus automatic temperature compensation is based on the sound velocity /
temperature characteristics of air and may not be suitable for other atmospheres. If the
atmosphere temperature is variable, frequent Sound Velocity Calibrations may be
required to maintain optimum measurement accuracy.
Sound Velocity calibration frequency may be determined with experience. If the sound
velocity in several vessels is always similar, future calibrations may be performed on one
of the vessels and the resultant Velocity (P653) entered directly for the other vessels.
If the sound velocity of a vessel atmosphere is found to be repeatable at specific
temperatures, a chart or curve may be developed. Then, rather than performing a Sound
Velocity Calibration each time the vessel temperature changes significantly, the
anticipated Velocity (P653) may be entered directly.
Scanning
When echo processing is complete, (if more than one vessel is monitored) the scanning
relay changes state to supply the transmit pulse to the next transducer to be scanned,
after the Scan Delay (P727).
Scan Delay is automatically set by Measurement Response (P003). When high speed
scanning is required (sometimes the case for equipment position monitoring), the Scan
Delay may be reduced. Reduce the Scan Delay only as required, otherwise premature
scanning relay fatigue could occur.
All vessels are scanned sequentially unless a Point Number is "on priority" (see Smart
Scan, P720). If #1 of four vessels is on priority, the scanning sequence is 1,2,1,3,1,4,1,2,1,3,1,4
and so on.
Volume Calculation
The XPL Plus provides a variety of volume calculation features (P050 to P055).
If the vessel to be monitored does not match any of the eight preset Tank Shape
calculations, a Universal Volume calculation may be used. Use the level / volume graph or
chart provided by the vessel fabricator (or create one based on the vessel dimensions).
From this graph, determine which Universal Volume calculation will provide the best
results, and select the level vs volume breakpoints to be entered (32 max.). Generally, the
more breakpoints entered, the greater the volume calculation accuracy.