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Black Water Tank Sending Units

Posted: Thu Mar 22, 2018 8:00 am
by ehsvp
Hi All,
What are people using for black water tank sending units? My digital displays only accept analog inputs for tank sending units. I'm looking for good quality sending units that won't malfunction in a black water tank.

Bob

Re: Black Water Tank Sending Units

Posted: Thu Mar 22, 2018 10:09 am
by Krisinak
finding a quality sending unit might be tough. please post what you find. i would like to source one too. good luck

Re: Black Water Tank Sending Units

Posted: Thu Mar 22, 2018 12:28 pm
by kmorin
ehsvp, Krisinak, something like this technology may be worth checking out?
https://senix.com/ultrasonic-tank-level ... lications/ the non-contact but corrosive atmosphere in a black water tank may well be a good app for this type level sensor?

I don't know their product well enough to say their sensor can provide a signal your system will accept. Since this is a commercial/industrial product and they claim to provide an analog signal- then... it may provide a standard 4-20Ma = 0% to 100% signal type, (one of several common analog signals in industrial instrumentation) and-?? that may be field adjustable? or... sometimes the column of measurement is set by the model # of sensor you buy. So a 12" deep tank may be full range of Model 12-0 ?? Then a 24" deep tank may be a Model 24-0 ??

I'd say the signal types' compatibility with your input types is the critical path? Then I'd want to read their literature about installation and the radiated cone and return to confirm their sensor was applicable to your tank shape?

At least give these types of sensors a look? I 'd want to be very careful about the install provisions since ultra-sonic level is kind of notorious for sensor location above the tank fluids- they operate with cones of sound emanating from the transducer like a depth sounder does. Therefore, making sure your tank design allows for the sensor face to have no "stilling well column" may be important to the operation?

It will be interesting to see how your searches turn out?

Cheers,
Kevin Morin
Kenai, AK

Re: Black Water Tank Sending Units

Posted: Thu Mar 22, 2018 4:29 pm
by kmorin
quick link to a paper/pdf on the types of sensors, that may be useful in tracking down a vendor?
http://www.gilsoneng.com/reference/Levelpap.pdf

cheers,
Kevin Morin
Kenai, AK

Re: Black Water Tank Sending Units

Posted: Thu Mar 22, 2018 5:52 pm
by welderbob
KUS /WEMA USA. I'll get a picture tomorrow, we have some in the shop.
welderbob

Re: Black Water Tank Sending Units

Posted: Fri Mar 23, 2018 7:15 am
by ehsvp
Thank you to everyone for the replies. My Icon Touch 7.0 displays have analog inputs for the sending units. This rules out the ultrasonic units unless I want to buy a separate display for the sending units. I've researched the WEMA units and was curious to see if anyone had used the SHS holding tank level sensor. It looks well build and difficult to clog. I believe these units are analog so they should work with my displays. Welder Bob, how have these units worked in your builds?

Bob

Re: Black Water Tank Sending Units

Posted: Fri Mar 23, 2018 7:45 am
by ehsvp
I did find some electronic capacitance units made by Gill which might work but the WEMA units seem to be used by lots of people. Kevin, thanks for the response, I will look into these as well.

Bob

Re: Black Water Tank Sending Units

Posted: Fri Mar 23, 2018 10:15 am
by welderbob
The sending units come with there fancy mounting ring. We weld a 1 1/2 NPT fitting in the tank and screw in. Generally they recommend a length about 3/4 of the depth of the tank. The sender with out the protective cover is a fuel sending unit, but the float is the same as the blackwater one. The gauge is there LED light one. They will also make this with an alarm sensor.

Start of a 300 gallon welded plastic waste tank.

We haven't had any come back.

Welderbob

Re: Black Water Tank Sending Units

Posted: Fri Mar 23, 2018 12:02 pm
by kmorin
Bob,
It looks like the float type with the stilling wells installed over the float- to allow liquids only into the well solves the black water challenges of mixed solids in the measured column? So that looks like a simple and easy to install solution?

But, on a related topic as a note about sensor signalling in general. The term analog usually means the circuit reading can be obtained by either a voltage or current signal. That is; the sensor control circuit or monitoring device- regardless if it is a display (only) or a digital (calculating) system- is powered by DC and the returned (attenuated) voltage or current is translated into a proportional 'reading' or value of the length of the measured column.

For example; the float type 12" (approx) probe shown probably has a magnetic coil in the float- and that creates a changing value in the control circuit due to the variable position on the corresponding 'measuring element' inside the non-magnetic SS tube. These units may be considered analog if they are powered by the control circuit (usually 12 or 24VDC) and the the circuit boards at the 'top/head/conversion housing' simply attenuate voltage or current. Current (milli-amperage)is common because the distance to the sensor's monitoring circuit is effected by the length of conductor distorting a voltage signal; but current (4-20mA is common) is not affected by the length of conductor.

The ultra sonics come in both analog signals and digital signaling - not all brands of all types will be sold in both types of signaling so that is why I thought you'd have to look at your Icon Touch 7 to see what types of signals are accepted? It is possible that it does in fact accept 4-20mA at 24VDC (very common industrial control loop signal) but then it may be designed for a line of proprietary products with other analog signal standards??

I've designed and built systems that take 4-20mA signals into PLC's from more than dozen mfg's. and all accepted the standard signals in the loop (driven control and data circuit) but some sensor manufactures' products are designed to help sell their own equipment so they have to be purchased to match a unique signal type or value.

As to digital signaling from sensors, sometimes referred to as 'smart' transmitters (not to be confused with RF devices in most uses of this term) it is most common these sensors/transmitters will have a digital conversion in their head or top housing. These types of pressure, level, temperature, flow or analytical transmitters/sensors all communicate over a 'network' type of wiring scheme. These are typically the types of physical sensors (transmitters) that will be used in a single screen display from Raymarine, Furuno types of vendors.

The only matching headache for digital sensor communications is the communications protocol or 'addressing' type used for any given device. Like matching analog standard signals, the network protocol employed in the manufacture of the digital or smart/addressable sensors needs to match for them to work with one or another brand of control/"poller"/display.

[just some notes in the overall discussion so those reading it have enough background info to make our discussion clear to the new comer to boat wiring.]

Hope you find a sensor that gives reliable service.

Cheers,
Kevin Morin
Kenai, AK

Re: Black Water Tank Sending Units

Posted: Sun Mar 25, 2018 6:46 am
by ehsvp
welderbob wrote:
Fri Mar 23, 2018 10:15 am
The sending units come with there fancy mounting ring. We weld a 1 1/2 NPT fitting in the tank and screw in. Generally they recommend a length about 3/4 of the depth of the tank. The sender with out the protective cover is a fuel sending unit, but the float is the same as the blackwater one. The gauge is there LED light one. They will also make this with an alarm sensor.

Start of a 300 gallon welded plastic waste tank.

We haven't had any come back.

Welderbob
Perfect, thanks Bob

Re: Black Water Tank Sending Units

Posted: Sun Mar 25, 2018 6:47 am
by ehsvp
Perfect, thanks Bob.

Re: Black Water Tank Sending Units

Posted: Sun Mar 25, 2018 6:47 am
by ehsvp
kmorin wrote:
Fri Mar 23, 2018 12:02 pm
Bob,
It looks like the float type with the stilling wells installed over the float- to allow liquids only into the well solves the black water challenges of mixed solids in the measured column? So that looks like a simple and easy to install solution?

But, on a related topic as a note about sensor signalling in general. The term analog usually means the circuit reading can be obtained by either a voltage or current signal. That is; the sensor control circuit or monitoring device- regardless if it is a display (only) or a digital (calculating) system- is powered by DC and the returned (attenuated) voltage or current is translated into a proportional 'reading' or value of the length of the measured column.

For example; the float type 12" (approx) probe shown probably has a magnetic coil in the float- and that creates a changing value in the control circuit due to the variable position on the corresponding 'measuring element' inside the non-magnetic SS tube. These units may be considered analog if they are powered by the control circuit (usually 12 or 24VDC) and the the circuit boards at the 'top/head/conversion housing' simply attenuate voltage or current. Current (milli-amperage)is common because the distance to the sensor's monitoring circuit is effected by the length of conductor distorting a voltage signal; but current (4-20mA is common) is not affected by the length of conductor.

The ultra sonics come in both analog signals and digital signaling - not all brands of all types will be sold in both types of signaling so that is why I thought you'd have to look at your Icon Touch 7 to see what types of signals are accepted? It is possible that it does in fact accept 4-20mA at 24VDC (very common industrial control loop signal) but then it may be designed for a line of proprietary products with other analog signal standards??

I've designed and built systems that take 4-20mA signals into PLC's from more than dozen mfg's. and all accepted the standard signals in the loop (driven control and data circuit) but some sensor manufactures' products are designed to help sell their own equipment so they have to be purchased to match a unique signal type or value.

As to digital signaling from sensors, sometimes referred to as 'smart' transmitters (not to be confused with RF devices in most uses of this term) it is most common these sensors/transmitters will have a digital conversion in their head or top housing. These types of pressure, level, temperature, flow or analytical transmitters/sensors all communicate over a 'network' type of wiring scheme. These are typically the types of physical sensors (transmitters) that will be used in a single screen display from Raymarine, Furuno types of vendors.

The only matching headache for digital sensor communications is the communications protocol or 'addressing' type used for any given device. Like matching analog standard signals, the network protocol employed in the manufacture of the digital or smart/addressable sensors needs to match for them to work with one or another brand of control/"poller"/display.

[just some notes in the overall discussion so those reading it have enough background info to make our discussion clear to the new comer to boat wiring.]

Hope you find a sensor that gives reliable service.

Cheers,
Kevin Morin
Kenai, AK
Thanks Kevin

Re: Black Water Tank Sending Units

Posted: Sun Mar 25, 2018 6:48 am
by ehsvp
Thanks Kevin

Re: Black Water Tank Sending Units

Posted: Sun Mar 25, 2018 6:48 am
by ehsvp
Thanks Kevin