Diesel/oil in bilge with auto. bilgepump. What now

[HopCar]

"I'm sure this pump works on the principle of a watersensor where probes detect water. As you know , diesel or oil has no conductivity so the will not be activated."


Bobs the Rule, Whale and Johnson field effect switches do not rely on the conductivity of water and can not be contaminated by oil. The Water Witch switch does rely on the conductivity of water.


I have no idea what Field Effect is but it seems to work pretty well. It's just magic to me.

[a64pilot]

Could it be as simple as a float that won't float in lower density fuel or oil?

[HopCar]

A64 that's pretty clever. I like it.

[Dsanduril]

A solid polypropylene float generally has a specific gravity between 0.90 and 0.95 and works well in this application. Most of the Teflon family floats are ~0.85. And you can get SS floats with varying SG values. Gems Sensors has a huge selection:

Small Size Single-Point Float Switches - Gemsâ„¢ Sensors

with just about any specific gravity you could want.

[bobs]

Originally Posted by a64pilot

Could it be as simple as a float that won't float in lower density fuel or oil?

You probably hit the spot A64.
And to be honest , really , before starting this topic , it had crossed my mind to experiment with different floaters on water and diesel to see if a solution could be found in that area.

Hopcar , the thing is also that I have my bilgepump installed in combi with a floaterswitch in the cavity of the bilge that controls the pump. You all know the system of course.
So buying this field effect switch pump would force me to reorganize the bilge.
What I would like to do is run an extra switch that can override the floaterswitch in case diesel/oil is in the cavity , or bilge for that matter.
I'll get to the boat in a few weeks time and will change the dieselfilter and experiment with some water. Never done that before , so it would be a reassurance to know the waterdetection works as fuel-injectionpump-guard.
I will also look into the density aspect , and try to find the correct floater.
Will let you know, but as always , suggestions a more than welcome.

Regards

[KDH]

Second the diesel/oil absorbing material and the Water Witch. Works well and we have the manual over ride switch for extreme emergency like sinking at sea. I have also physically isolated my engine bilge from the rest of the bilge and use a sump pump alarm to alert in case water starts to come in from the shaft tube. The plug on the engine bilge is easily removed but in the event of water intrusion the tiny drain hole does not move the water to the main bilge fast enough to keep up anyway. Routine inspection and maintenance helps a lot with that lingering anxiety.

[shaneinseattle]

Be careful with using the Water Witch switch. Once oil or fuel coats the electrodes the switch may not activate in any amount of water. I've had that problem. Twice. Nice that it won't pump out polluted water, but many bilges have some amount of oil that while not an environmental concerns, is enough to disable a WaterWitch switch.