Black water sensor - any recommendations / best practise?

[Dirk01]

I'm looking for the best recommendation/experience on a black water sensor.
Reliable measurement over a long period of time and easy replacement if the sensor fails should be possible.
If possible, it should be possible to measure “from above”. Each additional hole in the lower tank area is another potential source of error and unpleasant when replacing the sensor.
The type of measurement result is basically irrelevant (voltage, current, resistance, switching stages, N2k, SAE1939, CANopen...). But a continuous measurement (0...100%) is advantageous.

I've searched the forum but couldn't find a post with a relevant title.

Recommendations or links to specific products are most welcome.

Cheers
Dirk

[Sailorman97]

https://www.amazon.com/Moeller-03576...3390998&sr=8-1

Here you are. Should do it.

[goboatingnow]

The common ones are a simple float magnet and a set of reed switches in a watertight tube , usually surrounded by a slotted “debris “ shroud. In mine I fitted a small nipple to allow water to be flushed down the inside of the shroud , as the problem I found is the material gums the float up . The wash down cured that.

Other then that these sensors are very simple and reliable and fitted from the top.

[GordMay]

Just a few of our relevant discussions:

“Tank liquid level senders” ➥ https://www.cruisersforum.com/forums...ml#post3050637

“Stick-on Holding Tank Level Sensor” ➥ https://www.cruisersforum.com/forums...ml#post2036839

“Ultra sound water tank sensor” ➥ https://www.cruisersforum.com/forums...ml#post1127379

“Black water tank level indicator” ➥ https://www.cruisersforum.com/forums...ml#post1981576

“Black Water Tank Level Indication” ➥ https://www.cruisersforum.com/forums...ml#post1051038

[Dirk01]

Sensors with a moving part tend to clogg. Like goboatingnow describes it needs to be serviced more or less regularly. That's what I like to avoid.
Addition: The power consuption is not of a concern. I'll have a remote controlled switch which will be activated after a flush into the BW tank (deverting valve will have a switch also). The actual value is stored with a time stamp and can be checked on a display. Reaching a certain level gives a warning (70%) and an alarm (90%).

Cheers
Dirk

[Dirk01]

Originally Posted by GordMay

Just a few of our relevant discussions:

“Tank liquid level senders” ➥ https://www.cruisersforum.com/forums...ml#post3050637

“Stick-on Holding Tank Level Sensor” ➥ https://www.cruisersforum.com/forums...ml#post2036839

“Ultra sound water tank sensor” ➥ https://www.cruisersforum.com/forums...ml#post1127379

“Black water tank level indicator” ➥ https://www.cruisersforum.com/forums...ml#post1981576

“Black Water Tank Level Indication” ➥ https://www.cruisersforum.com/forums...ml#post1051038

Many thx to you GordMay.
I've A LOT to learn to find that discussions.
Hopefully there's an appropriate answer.

Ashes on my head.

Cheers
Dirk

[mickand]

Gobius Pro - sends an ultrasonic pulse through the tank at intervals you determine. Wifi and an easy install

[sinnerman]

Saw this installed on a Ronco plastic holding tank:

https://www.emarineinc.com/SCAD-TM1-TM2-Tank-Monitor

No holes in tank. Everything is external.

Not sure how well it works, but there is a lot of crap (pun intended) in the holding tank that can foul a floating or pressure-operated tank monitoring sensor.

cheers

[hgd137]

Originally Posted by goboatingnow

The common ones are a simple float magnet and a set of reed switches in a watertight tube , usually surrounded by a slotted “debris “ shroud. In mine I fitted a small nipple to allow water to be flushed down the inside of the shroud , as the problem I found is the material gums the float up . The wash down cured that.

Other then that these sensors are very simple and reliable and fitted from the top.

Could you explain in greater detail what you did to solve the fouling problem which can be expected with such an arrangement as a donut sliding up and down a tube in a very hostile environment?

[Hermia II]

I'm using Maretron TLM100 which is an ultra sonic device with a special "stand tube" for black water. I use the same in all other tanks, eight in all. It works flawlessly and you can calibrate each tank sensor, taking account of the curvature of the tanks, to show the actual content i Gallons or Liters. View the whole thing through the N2K-viewer which has endless options.

[goboatingnow]

Originally Posted by hgd137

Could you explain in greater detail what you did to solve the fouling problem which can be expected with such an arrangement as a donut sliding up and down a tube in a very hostile environment?

I drilled the top plate and fitted a nipple with a small shut off , the output of this is inside the shroud

My experience is that over time solid material jammed the movement of the float magnet because the shroud is supposed to ensure the float is exposed to primarily liquid. However some solids get in and especially if you tend to have a empty tank most of the time the float jams.

Water can be introduced through the washing nipple and this helps clean the inside of the shroud

This is the typical float based black water sender

[Lancerbye]

I use Tank Tender which has four ports, no electric components, I measure Diesel, 2 tanks, fresh water, and waste water. This has been on this boat for 40 years, no problems. Simplicity is best.

[Russ]

Yup a big ditto for Tank Tender. Occam’s Razor

[Howler]

Gobius Pro is a great solution, requiring no holes or complex installation, other than providing a trickle of 12V power (I even used a small dedicated LiOn battery to avoid any wiring… one charge lasts all season).

If you’re interested, send me a PM as I have two for sale: one used a few seasons and one new, never removed from the box. I also have extra 3M custom adhesive pads for attaching the used sensor to the tank.

[blubaju]

Originally Posted by Lancerbye

I use Tank Tender which has four ports, no electric components, I measure Diesel, 2 tanks, fresh water, and waste water. This has been on this boat for 40 years, no problems. Simplicity is best.

Same here, since 1990, no problems, well, a red led for night viewing could be an improvement