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Wire Float Level Sensor How To Properly Attach The Float To The Cable

FILED UNDER: Wire Float

Symptom

The way our wire float level sensor works is, the float sits on the surface of the oil in the tank.  The float rises up and down as the oil level changes and as it does, the cable to which the float is attached winds on and off a take-up reel inside the sensor’s head.  The 4-20mA signal that the sensor puts out depends on how far the cable is pulled out.  That 4-20 mA current goes back to our tank gage where it is interpreted as both an oil level in inches (or centimeters) and a corresponding number of gallons (or liters).

The float itself is shipped loose, separate from the level sensor, and it gets attached in the field.  That’s because the float needs to be attached to cable at precisely the right spot.  And that spot depends on the vertical distance between the highest possible oil level in the tank and the surface of the flange that the wire float is going to mount to.  This distance varies with each installation and depends on factors such as whether the tank is a double wall tank or not and the height of the riser leading up to the flange.

This is the level sensor head.

This is the stainless steel cable that pays in and out of the head depending on the oil level.

This is the wire sleeve which is used to locate on the float on the wire.

And this is the float that sits on the surface of the oil that gets attached to the wire.

Steps to Troubleshoot

The first thing you’re going to need to do is measure the distance from the highest point in the inside of the tank to the top side of the flange that the wire float will be mounted to.

Camera: Show a measurement being taken on a cutaway tank w/ riser. Or alternatively, use a picture with a pointer and show the “x” distance.

In this example we measure x’-x”.

Now we add 6-3/16” to that.  That gives us a total distance of y’-y”.

This is the distance that should be between the top of the wire sleeve and the top of the float after it’s tied on.

Now that we know our distance we can tie our float onto the wire.

I’m going to measure from the top of the sleeve and make a mark on the wire with a sharpie and flag it with a piece of tape so I won’t lose track of the mark.

To tie the float onto the wire, you thread the wire down through the hole in the center of the top of the float, then, back up through the other hole out of the top of the float.  Pull the wire through the float until your sharpie mark is at the top of the float.  Make sure the wire is taut coming back through the block.  Wrap the wire twice around the screw and then tighten the screw firmly to fasten the wire in position.  

Resolution

Double check your work.  Measure the distance from the top of the float to the top of the sleeve on the wire.  Verify that the distance is the same as the distance from the highest possible oil level and the top side of the flange that the level sensor will mount to, plus 6-3/16”.

If you used tape to flag the sharpie mark on the wire, remove it now.

Before you mount the head on the flange there’s one last step.  The wire float level sensor is shipped with a “Drag Brake Spring” and a “Drag Brake Retaining Screw” installed in the side of the head.  These add resistance to the motion of the take-up reel so the moving parts don’t get damaged during shipping or handling.

You can now remove the Drag Brake Retaining Screw and then the Drag Brake Spring so the take-up reel is free to move and the wire is free to wind on and off of it.  But be careful.  Sudden movements can damage the sensor.  You must not to allow the float to free fall.  Support the float as you handle the sensor and when you put the float into the tank, lower it slowly to the surface of the oil.  Then bolt the head down.