Revision 1.5
Page 5
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 Other Operational Notes
There is a 15 second filter associated with the sensor to provide stability in pitching and rolling
seas. Any rapid change in fluid level will take 15 seconds for the sensor to catch up with the
tank. If someone rapidly fills or empties a tank, they may think there is a problem while the filter
catches up.
Filling a diesel tank (or sloshing around in a seaway) can create foam on top of the fluid. If
there is enough foam, there won’t be a good reflective surface for the signal to bounce off of
and return to the sender. Most well installed fuel tanks have the filler tube extend to near the
bottom of the tank, which prevents foam, but if not, it will take some time before you get a
stable reading after filling the tank.
Testing the TLM100 outside a tank is not recommended. The sensor has a hard time with
instantaneous changes to the distance being measured, which never happens when installed
on a boat since the tank can’t be filled or emptied instantaneously. For example, if you hold the
sensor above a table at 10” and then move it away from the table to the floor 40” away, the
sensor experiences a step or instantaneous change that causes it to start range finding.
Sometimes it will quickly find the floor, other times it will take a long time. Please don’t judge
the TLM100 based on its performance outside a tank as this does not accurately reflect the
operating conditions for which the TLM100 was designed.
2.4 Mounting the TLM100
2.4.1 Preparation of the TLM100 Sensor Component
The accuracy of the TLM100 can be affected by condensation of water or splashing of water or
fuel on the surface of the ultrasonic sensor. The TLM100 comes with a packet of petroleum
jelly in order to repel the condensation. Open the packet and spread a thin layer of petroleum
jelly on the bottom face of the sensor component.
2.4.2 Mounting the TLM100 Sensor Component
The TLM100 comes from the factory ready to mount on a tank with the standard SAE J1810 5-
Hole mounting pattern. Maretron offers adapters to allow mounting the TLM100 on a tank with
a 1.5” NPT connection or a 1.25” BSP connection.