Milltronics PL-513 User Manual

P-63, velocity at 20 °C can be used to enter the known velocity at 20 °C of sound in a
particular gas or vapour to view the resultant velocity of a sound velocity
compensation, normalized to 20 °C.
P-64, velocity at P-65, can be used to enter the known velocity of sound in a particular
gas or vapour, or to view the resultant velocity of a sound velocity compensation, at
the temperature of P-65.
Refer to Appendices/Sound Velocities, for typical sound velocities in various gases
and vapours.
BLANKING
Near blanking (P-5) is used to ignore the zone in front of the transducer where ringing
or other false echo is at a level with the processing of the true echo.
Ringing is the inherent nature of the transducer mass to continue vibrating after the
transmit pulse has ceased. The amount of ringing varies with the type of transducer
used and decays to acceptable levels in the order of milliseconds. Excessive cold and
overtightening of the transducer mounting will increase the ring time such that it may
appear as an echo during the receive cycle. This is usually indicated by an incorrect
high level reading. This condition may be verified with the use of an oscilloscope and
may be overcome by increasing the near blanking (refer to Troubleshooting).
Far end blanking is a design function that ignores the zone below the zero or empty
level where false echoes may appear at levels that interfere with the processing of
true echo.
In applications where the zero level is above the bottom of the vessel and it is desired
to monitor the zone below the normal zero, range extension (P-87) may be used to
extend the range into the far end blanking. Range extension is entered as a percent of
P-3. As range extension reduces the protection afforded by the far end blanking, it
should be used judiciously. Avoid excessive range extension as this may reduce the
ringing
true echo
(level)
false echo
end of
transmit
0
level
typical receiver signal
P-5
near blanking
far end
blanking
empty distance to transducer
P-3
range
range extension (P-87)
as % P-3
typical processed signal
PL-443 5 – 3

Milltronics PL-513 Specifications

General

Brand	Milltronics
Model	PL-513
Category	Measuring Instruments
Language	English