Maretron TLM100 - Manual (Page 8)

TLM100 User’s Manual
Page 4 Revision 1.3
• The sensor component of the TLM100 must be mounted over the deepest part of
the tank, in order to obtain accurate depth readings when the tank is empty or
near empty.
• In order to obtain accurate readings when the tank is empty, the tank bottom
directly under the TLM100 must be both smooth and flat, so that the ultrasonic
sound waves transmitted by the sender are reflected back to the sender for
measurement. If the tank bottom under the TLM100 is sloped, grooved, or rough,
then the TLM100 may not report an accurate level reading (or any level reading
at all) when the tank is empty.
• The area below the sensor component of the TLM100 must be free of obstruction
from tank baffles or return lines that might reflect ultrasonic waves back towards
the sensor component, causing inaccurate depth readings.
• The sensor component of the TLM100 must be mounted away from the tank
walls, so that reflections from the tank walls do not cause inaccurate depth
readings.
• For a flat bottom tank, the mounting hole in the top of the tank through which the
TLM100 measures fluid level should be located as close to the center of the tank,
both front-to-back and side-to-side, as possible. This will ensure maximum
accuracy of reading in the event that the vessel experiences pitch and roll.
2.3.1 Effect of Pitch and Roll on the TLM100
Assuming that the TLM100 sensor component is mounted on a flat tank top, the TLM100 will
operate correctly as long as the vessel does not experience pitch and/or roll in excess of 6° for
an extended period of time. This can occur on a sailboat when the boat is heeled over, or on a
powerboat with a non-displacement (planing) hull. Temporary pitch and roll due to wave
motion and will not adversely affect tank level readings.
If you are in a sailing vessel or a powerboat with a non-displacement hull and will experience
pitch and/or roll in excess of 6° for an extended period of time, you can install a Non-
Displacement Hull Focus Tube below the sensor (please refer to Section 1.5 on page 2 for
ordering information). This is a tube which mounts into the tank before the sensor and directs
the ultrasonic waves down to the surface of the liquid and back. With a focus tube, the
TLM100 will operate correctly as long as the vessel does not exceed 15° of pitch and/or roll for
extended periods of time.
2.3.2 Use of an Airlock on Black Water Tanks
Maretron highly recommends the use of an airlock (please refer to Section 1.5 for information
on available airlocks) in black water tank applications. Use of an airlock will prevent the face of
the ultrasonic transducer from becoming fouled with tank contents, but will limit the minimum
depth that the TLM100 can sense to the depth of the airlock component, as the liquid will not
rise above the bottom of the airlock.