APPENDIX B - APPLICATIONS BACKGROUND
Conditions in the tank where the ultrasonic sensor is installed can affect the performance, range and
accuracy of the system. The following notes are for general reference. Contact Greyline Instruments or
your local representative for specific information on your application.
FOAM - Solid or dense surfaces such as a smooth liquid surface will give the best echoes in an
ultrasonic level measuring system. Foam acts as a sound insulator and may eliminate, or reduce the
strength of an echo. Measurement range may be reduced in a system where foam is present. Ultrasonics
are not recommended where thick dense foam is continually present. Intermittent or thin layers of light
foam (1/8 in. or less) can generally be disregarded. Use a stilling well in open channel applications.
LIQUIDS - The LIT25 is ideal to monitor tank liquid level or inventory. Caustic, corrosive or very
viscous liquids can be monitored without contacting the liquid.
SOLIDS - The LIT25 will measure most granular material and powders as well as liquids. Powders will
not generally provide the same echo strength as liquids. Therefore maximum expected range should be
reduced to approximately 20 feet (6 m) for powders. There are many exceptions to this rule and
installation of a test system is recommended when in doubt.
DUST - Any obstructions to the sound will affect performance of the system. In silo’s where heavy
concentrations of dust are expected ultrasonics may not work. Where moderate dust is encountered care
should be taken to mount the sensor in a position where dust accumulation will be minimized and where
the sensor can be cleaned if necessary.
SENSOR TEMPERATURE - The standard sensor model PZ32T supplied with each Level Indicating
Transmitter includes a built-in temperature sensor. The LIT25 automatically compensates for
temperature fluctuations to retain high accuracy. Note the operating temperature ranges listed in the
product specifications section. Do not exceed the sensor temperature ratings or damage may occur.
ELECTRONICS TEMPERATURE - Note operating temperature ranges listed in the product
specifications. Temperatures higher than the maximum shown can reduce the operating life of the
electronics. Moisture condensation from those temperatures below the range shown can also damage
electronics components.
NOISE - Because the LIT25’s sensor operates at high sound frequency, regular process noise or
vibration will not affect the system. Ultrasonic Sensors installed in close proximity to one another in the
same tank may “cross-talk” and should be relocated.
VAPOUR - May affect operation. Severe vapour stratification can cause false echoes. Variable vapour
cannot be compensated.
CHEMICAL COMPATIBILITY - The LIT25 Sensor is constructed of very durable materials with
broad compatibilities. Tank contents should be checked for their compatibility with PVC. An all-teflon
sensor is available for corrosive applications.
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LIT25 Level Indicating Transmitter
Manual Series 3.5.1
