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Determining Mag Probe Length
Probe Manhole Installation
At each underground probe location there must be a 14-inch (356 mm) minimum diameter manhole. If necessary
you must install this manhole according to the manufacturer’s instructions (Note: probes should not be located
within 24 inches (610 mm) of the submersible pump (STP) to avoid erroneous probe readings when the pump is
running). Position the manhole so that there is necessary clearance for junction box installation and wiring.
Determining Mag Probe Length for Installation in a Dedicated Riser
If tank diameter is unknown, perform the following procedure (ref. Figure 7):
1.
Measure the distance from the bottom of the tank to the top of the probe riser pipe (A).
2.
Measure the distance from the bottom of the probe riser pipe to the top of the probe riser pipe (B).
3.
Subtract (B) from (A) to determine the correct tank diameter (C). Round tank diameter (C) up to next highest
inch and order this length probe.
Figure 7. Calculating the Correct Mag Probe Length for dedicated riser installation
Legend for numbered boxes
1
Tank
2
STP
3
24” (610mm) minimum
4
Probe riser pipe
5
Dimension B
6
Dimension A
7
Dimension C or probe length = dimension A minus dimension B
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