10.3 Flex Probe Installation
Proper operation of the ATG system using the flex probe depends on
the correct sizing of the probe. If the probe is too long, it will touch the
bottom of the tank and bow, causing either inaccurate or lost
readings. If it is too short, product measurement range will be
compromised.
NOTE: Each Flex Probe is custom made to fit a particular tank. They
are not returnable if an error is made in determining the correct
length.
10.3.1 Flex Probe Length Determination
1. The flex probe mounts to the tank with a ¾-inch NPT
male thread. Obtain the proper fittings to adapt the
tank opening to a ¾-inch NPT female thread. Do not
use the tank’s vent opening to install the flex probe.
2. Temporarily install this hardware in the tank opening.
3. Using a plumb bob or measuring tape measure the
distance (in inches) from the top of the ¾-inch NPT
flange to the bottom of the tank. Save this
measurement, which will be Total Height (TH).
4. Flex probes are ordered by overall length (OAL).
Overall length is the distance from the top of the ¾-
inch NPT wiring bushing to the tip of the probe. OAL
(inches) = 1.5 + (TH x .993)
• If cable runs to 750 feet (229 m) use Belden #88761
• If cable runs to 1,000 feet (305 m) use Belden
#8760, #88760 or #8761
NOTE: Some electrical codes require intrinsically safe wiring to have
a blue jacket.
10.3.2 Flex Probe Installation Preparations
1. Measure the product level in the tank. Keep tank out
of service to prevent product level from changing.
2. Make note of the probe information found on the
probe serial number tag.
3. Locate standard plumbing fittings that will adapt your
tank opening to the ¾-inch NPT required for the
probe.
4. Wipe any excess sealant from the inside of the fittings
to prevent any from getting on the probe shaft during
installation.
CAUTION: Do not remove yellow tag; refer to image in Section 10.1.
Figure 10-2 Flex Probe Installation Diagram
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