Help finding 0-1 psi tank sensor

SearayPaul

Active Member
Oct 11, 2006
961
Simpsonville, South Carolina
Boat Info
34 Downeaster
Engines
Cummins 5.9 480hp
I am experimenting with the Maretron tank monitoring system.

https://www.maretron.com/products/fpm100.php Click the accessories tab to see the sensor type I am trying to locate.

The tanks I have for fuel, fresh water, and black water require a 0-1 psi sensor which Maretron can not supply. I need three external sensors and 1 submersible sensor rated 0-1 psi. The submersible sensor will be in the waste tank.

Does anyone know where I can obtain a 0-1 psi sensor? Google has not been able to locate the correct sensor and Maretron will not divulge their supplier. Thank you
 
Am i missing something here? It appears that you have purchased the Maretron controller and they wont offer any help with supplying the needed sensors ?
 
Maretron just does not have the sensor I need. If I can not find the sensor I will try the 0-1.5psi sensor Maretron stocks. The problem with the 0-1.5psi sensor is that it is for a taller tank than I have. This affects the accuracy. How much it will affect accuracy I do not know as I am not an engineer.
 
Read this. Guy is doing exactly what you are. Found some inexpensive sensors. For testing, probably sufficient, but Maretron stuff seems pretty good and not expensive relative to some of the commercial stuff available.

Report back how this goes. Following...

https://www.panbo.com/better-waste-tank-monitoring-with-maretron/

For information, what are the depths of the tanks you want to monitor?
 
4 to 20 ma is what Maretron uses. I just did their ultrasonic liquid level system; search for posts by me.
When you get into the inches of water column ranges the prices go up quite a bit. I use Dwyer a lot and used them on my last boat for transmission oil pressure. These type of transducers are sensitive to the slightest pressure fluctuations and will show pressure all over the map; they need to have a small orifice installed with them to dampen the tank surging.
https://www.dwyer-inst.com/Product/Pressure/SinglePressure/Transmitters/Series672
 
Makes Maretron look cheap...
 
Maretron has been up front with me as to what sensors are available. I knew they did not have the sensor for my tanks. Maretron has been very good to me explaining what I need to find. This is NOT a Maretron bashing thread.

All of my tanks are about 15 inches tall. I have two fuel tanks that hold 200 gallons each, water is 125 gallons in one tank, and 50 gallons black water. In a perfect world a 0-.5psi sensor is what I would use.

I currently use an ultrasonic system in my holding tank. It is not dependable so I do not want to go down that avenue.

I read the article DTFELD pointed me to. Panbo is using a 16.5 foot sensor in a 32 inch tank. He seemed happy with the results. Maretron’s 0-1.5psi sensor has an accuracy of .3% and a Total Error Band of 1%. I would be using a 41 inch sensor in a 15 inch tank. Will this work good enough. 90% accuracy would make me happy on the waste tank.

Thanks for everyone’s help.
 
Any instrument will have issues over time with the black water tank due to solids accumulation. Reducing the solids with Noflex Digester is the first line of defense and should be routine maintenance regardless. The Maretron TLM series level indicators set in a bung an inch or two above the top of the tank without a focus tube is the best solution in my opinion. Make sure the sensor face maintains a thin coat of petroleum jelly over it. I think you will have more issues gunking up a pressure transducer and if it's the fully submerged type the wiring failing. Regardless, with any sensor in the black water tank it will need to be periodically removed and cleaned; it's a tough environment. Most importantly, never let the black water tank become completely full - set up your monitor to alarm a minimum of 4 inches from the top of the tank.
 
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Maretron has been up front with me as to what sensors are available. I knew they did not have the sensor for my tanks. Maretron has been very good to me explaining what I need to find. This is NOT a Maretron bashing thread.

All of my tanks are about 15 inches tall. I have two fuel tanks that hold 200 gallons each, water is 125 gallons in one tank, and 50 gallons black water. In a perfect world a 0-.5psi sensor is what I would use.

I currently use an ultrasonic system in my holding tank. It is not dependable so I do not want to go down that avenue.

I read the article DTFELD pointed me to. Panbo is using a 16.5 foot sensor in a 32 inch tank. He seemed happy with the results. Maretron’s 0-1.5psi sensor has an accuracy of .3% and a Total Error Band of 1%. I would be using a 41 inch sensor in a 15 inch tank. Will this work good enough. 90% accuracy would make me happy on the waste tank.

Thanks for everyone’s help.
Can you publish the exact accuracy spec of the Maretron sensor? Is the "Total error Band of 1%" for the entire range of the sensor? If so the Total Error should be 41inches X .01 = .41". So you could expect + or - .41" of error which equates to about a 2.7% total error. That's worst case. Some better sensors specify accuracy and error in terms of span or range, which means that they are adjustable and the accuracy only is considered for the range they are using. You also should consider the "turn down" spec. This usually doesn't become an issue until you start getting up around 8:1 or higher, i.e if you were trying to measure a 5" tank with a 40" sensor.
 
Olyson, the Total error Band was calculated for the entire range of the sensor. I can live with a 2.7% error. I was unable to obtain the “turn down” specification. I will be using the sensor in a tank that has a height of 15 inches. Is the error still 2.7%? The accuracy spec is .3% for the sensor. Thank you.
 
Olyson, the Total error Band was calculated for the entire range of the sensor. I can live with a 2.7% error. I was unable to obtain the “turn down” specification. I will be using the sensor in a tank that has a height of 15 inches. Is the error still 2.7%? The accuracy spec is .3% for the sensor. Thank you.
1.5 psi is the same as 41.56" of water column. I just googled the Maretron 1.5 psi sensor and the spec I saw said the accuracy is +/- 3% full scale. The max error should be .03 X 41.56" which is equal to 1.25" of water. The max error is still based on full scale so you could have as much as 1.25" of error. That equates to about 8.3%. The number got bigger because I used 3% instead of 1%. For the real world you probably just need to decide if you can live with it being off by 1.25".
 
Thank you for your help Olysan. I can live with this error. This is a huge improvement over my current 100% error. I appreciate your helping me to verify my math. I am not an engineer and was concerned about my understanding.

I will let everyone know how this turns out in October.

ZZ13... 95%:)
 

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