Author Topic: Measuring water in a water tank  (Read 19574 times)

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Offline ilium007

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Re: Measuring water in a water tank
« Reply #50 on: January 07, 2013, 09:36:44 am »
Actually not a bad idea at all. Regarding sound propagation, only one potential issue comes to mind: multiple signal paths caused by reflections from the pipe sidewalls. That can cause the echo to spread in time so that a naive detection may give inaccurate readings. Having said that, it however should be the case that the direct reflection from the water surface should be the shortest path and arrive first. Surely it can be made to work with a bit of labbing.

BTW the sensor looks interesting. Does DK or Mouser source them? I might be interested myself in that case.

I'm not sure - I got mine direct from Maxbotix: http://maxbotix.com/ and they sent it to me in Australia.
 

Offline Kremmen

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Re: Measuring water in a water tank
« Reply #51 on: January 07, 2013, 09:49:15 am »
OK, i'll look into it.
One more thing that occurs to me: take care not to use too high repetition rate with the sound pulses in order to avoid reverb echoes from ruining the result. This is something you can see in boat fishfinders that are very familiar to me and i am sure many others here as well. When you run in shallow water you can see ghosts of the true bottom repeated on the display. This is due to multiple reflections between the bottom and the boat hull. So either let them die out or use some damper material to absorb the sound energy. Probably the first one is easier since the water level won't change in a hurry, right?

P.S. Turns out Maxbotix even has a local distributor in Finland. Thanks.
« Last Edit: January 07, 2013, 09:54:08 am by Kremmen »
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Offline ilium007

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Re: Measuring water in a water tank
« Reply #52 on: January 07, 2013, 09:51:20 am »
OK, i'll look into it.
One more thing that occurs to me: take care not to use too high repetition rate with the sound pulses in order to avoid reverb echoes from ruining the result. This is something you can see in boat fishfinders that are very familiar to me and i am sure many others here as well. When you run in shallow water you can see ghosts of the true bottom repeated on the display. This is due to multiple reflections between the bottom and the boat hull. So either let them die out or use some damper material to absorb the sound energy. Probably the first one is easier since the water level won't change in a hurry, right?

Ok - will keep it in mind. The unit I had doing my original Arduino integration and testing didnt seem to have any issues. Maxbotix have software on the sensor that does a large amount of filtering. I was sending out 50 pulses, getting the results, bubble sorting them and them pulling out the median value all within a second or less ! It was always very accurate.
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #53 on: January 07, 2013, 10:00:03 am »
This is what is giving me hope !

http://maxbotix.com/articles/050.htm
 

Offline Kremmen

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Re: Measuring water in a water tank
« Reply #54 on: January 07, 2013, 10:24:54 am »
Yes, those things seem to be just the ticket, as they are made from this specific application in mind. Even the "raw" readings were really beautiful proving that there must be some serious signal conditioning going on already in the sensor unit itself. They have their price but it is most probably worth it going that way.
Nothing sings like a kilovolt.
Dr W. Bishop
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #55 on: January 07, 2013, 10:26:42 am »
Yes, those things seem to be just the ticket, as they are made from this specific application in mind. Even the "raw" readings were really beautiful proving that there must be some serious signal conditioning going on already in the sensor unit itself. They have their price but it is most probably worth it going that way.

Yes !! Pretty cool hey ?? Resolution down to 1mm ! I am soldering up the headers on mine now - might make the trek out to the water tank if I can get the LCD coded up tonight. So far I have got range data coming in via serial:

« Last Edit: January 07, 2013, 11:16:55 am by ilium007 »
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #56 on: January 07, 2013, 11:56:56 am »
This thing is amazing !! In 180us (yes, microseconds) I take 9 ultrasonic distance readings, sort them, find the median and output to an LCD !
 

Offline johnwa

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Re: Measuring water in a water tank
« Reply #57 on: January 07, 2013, 12:30:02 pm »

Ok - that looks promising ! Looks like you are in QLD as well ! I am still keen to look at this floating magnetic / hall effect array though. Given your efforts do you agree that information on doing this in the net as very hard to find ??!!

**edit given your username and time difference I assume you are in WA !

I am actually in vic - I don't think I could take the heat up north, it is bad enough here, 38C today!

There seems to be a fair bit of info out there on level sensing, you just need to know where to look. I hadn't done much research on the pressure sensors, as I had already got the article from SC.

The hall effect sensors are another valid possibility. I was thinking of doing something based on reed switches at one point, as I already had a bag full of them.

Your ultrasonic solution looks quite impressive!
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #58 on: January 07, 2013, 01:31:51 pm »
Ok - so here is progress so far. I am able to read serial data from the sensor and output on the LCD that will sit with the arduino out on the tank (undercover):

http://youtu.be/xZNCOu554So

Next steps are to sort out the code a little, and then get some outputs happening depending on water level. ie. turn on / off pumps. I will need to build a 10A MOSFET / SSD switch with opto-isolation from the 5V microcontroller. The Arduino is ethernet connected and the intention is to have the Arduino subscribe to an MQ server and it will send messages onto the MQ, I will then have the pump Ardunio subscribe to the MQ and it will turn on/off based on the messages that it receives. I have already prototyped this and it works perfectly.
 

Offline jerry507

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Re: Measuring water in a water tank
« Reply #59 on: January 07, 2013, 03:50:17 pm »
If you wouldn't mind, could you please tell us a bit more about your water setup? I'm stuck in the city so water service is simply a pipe running to my house. Why do you need all this tank storage? Do they fill up from rain or only from water deliveries? Etc etc etc. A really cool project, but also a really cool backstory I'm sure.
 

Offline MaxBotixInc

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Re: Measuring water in a water tank
« Reply #60 on: January 07, 2013, 11:02:01 pm »
Hello,

This is Scott Wielenberg from MaxBotix Inc.  I have seen your forum post and have noticed that you are looking for a sensor to monitor the level of a tank. I have also seen that you are looking for a sensor with temperature compensation.  You may wish to consider testing one of our new HRXL-MaxSonar-WR sensors with an external HR-MaxTemp connected to the sensor. 

The recommended sensor for tank level measurement is the MB7369 or MB7389.  Both sensors feature a Most-Likely filter that ranges to the target with the largest ultrasonic reflection and ignores smaller targets such as wires or pipes.  These sensors both have a maximum range of 5 meters and a 1 mm resolution and accuracy.  The difference between these sensors is the serial output.  The MB7369 has a RS232 seral data output, whereas the MB7389 has a TTL serial data output.  Both sensors have an Analog Voltage output and a Pulse Width output.

Our HRXL-MaxSonar-WR sensors have been proven to work extremely well in tanks.  We have done our own tank level measurement test that can be seen here http://maxbotix.com/articles/050.htm.
 
Please let me know if you have any questions by emailing me at scott@maxbotix.com.

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #61 on: January 07, 2013, 11:18:02 pm »
If you were to read the post you will see I bought one of your MB7389 sensors.
 

Offline IanB

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Re: Measuring water in a water tank
« Reply #62 on: January 07, 2013, 11:21:28 pm »
Coming late to the thread, but I should mention that in industry it is almost universal to measure liquid level in a tank using a differential pressure transducer. It just involves drilling a hole in the tank wall near the bottom and installing the pressure transducer in the opening created. If the liquid is corrosive or otherwise incompatible with the sensor, a protective diaphragm is placed between the sensor element and the liquid.

Compared to other options it has the advantage of simplicity and having essentially no moving parts. I know you ruled it out earlier on, but I suggest it might be worth revisiting.
I'm not an EE--what am I doing here?
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #63 on: January 07, 2013, 11:29:24 pm »
This has already been discussed. The cheapest diff press sensor in Australia is $575. I agree that a 4-20ma sensor would be best but I have 5 of these tanks to monitor.
 

Offline Mosaic

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Re: Measuring water in a water tank
« Reply #64 on: January 07, 2013, 11:37:36 pm »
Hi, I thought I'd share this as I did post a solution (on ETO) for something similar.

http://www.electro-tech-online.com/microcontrollers/131535-mpx2100d-mcu-water-level-measuring-project.html
 

Offline IanB

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Re: Measuring water in a water tank
« Reply #65 on: January 07, 2013, 11:41:11 pm »
The cheapest diff press sensor in Australia is $575.

That's crazy money, but I'm thinking it should be possible to home brew something based on the same principle at lower cost than that.
I'm not an EE--what am I doing here?
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #66 on: January 07, 2013, 11:47:13 pm »
The cheapest diff press sensor in Australia is $575.

That's crazy money, but I'm thinking it should be possible to home brew something based on the same principle at lower cost than that.

Thats what I thought but I have spent a lot of time looking into something else ! The Maxbotix sensor is the cheapest alternative. One would think it was not so hard to measure water !
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #67 on: January 07, 2013, 11:48:05 pm »
Hello,

This is Scott Wielenberg from MaxBotix Inc.  I have seen your forum post and have noticed that you are looking for a sensor to monitor the level of a tank. I have also seen that you are looking for a sensor with temperature compensation.  You may wish to consider testing one of our new HRXL-MaxSonar-WR sensors with an external HR-MaxTemp connected to the sensor. 

The recommended sensor for tank level measurement is the MB7369 or MB7389.  Both sensors feature a Most-Likely filter that ranges to the target with the largest ultrasonic reflection and ignores smaller targets such as wires or pipes.  These sensors both have a maximum range of 5 meters and a 1 mm resolution and accuracy.  The difference between these sensors is the serial output.  The MB7369 has a RS232 seral data output, whereas the MB7389 has a TTL serial data output.  Both sensors have an Analog Voltage output and a Pulse Width output.

Our HRXL-MaxSonar-WR sensors have been proven to work extremely well in tanks.  We have done our own tank level measurement test that can be seen here http://maxbotix.com/articles/050.htm.
 
Please let me know if you have any questions by emailing me at scott@maxbotix.com.

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.

I will also point out that I approached you guys with all of my questions and drawings etc for some assistance in the application of the sensor and was simply told to buy osne and see. Thats what I am doing here.
 

Offline Mosaic

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Re: Measuring water in a water tank
« Reply #68 on: January 07, 2013, 11:51:50 pm »
Hi OP:
How about a clear tubing water column with a coloured float connected to the outlet of the tank and matching the height of the tank?
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #69 on: January 08, 2013, 12:12:26 am »
Hi OP:
How about a clear tubing water column with a coloured float connected to the outlet of the tank and matching the height of the tank?

Ummmmm...

I am trying to electronically measure water in a tank to interface with a micro controller to turn stuff on and off..... so the plastic tubing fits in where ?
 

Offline Mosaic

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Re: Measuring water in a water tank
« Reply #70 on: January 08, 2013, 12:18:46 am »
Well  as u have a moving float u can sense it optically or electromagnetically (if it has a bit of ferrous metal in it).
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #71 on: January 08, 2013, 12:20:52 am »
Well  as u have a moving float u can sense it optically or electromagnetically (if it has a bit of ferrous metal in it).
Already been discussed in this thread. I need/want 1cm resolution (70l of water in my tanks) so to do this with Hall Effect sensors would seem quite difficult.
 

Offline mamalala

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Re: Measuring water in a water tank
« Reply #72 on: January 08, 2013, 12:22:29 am »
This has already been discussed. The cheapest diff press sensor in Australia is $575. I agree that a 4-20ma sensor would be best but I have 5 of these tanks to monitor.

Have you checked the MPX sensors from Freescale?

Greetings,

Chris
 

Offline ilium007

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Re: Measuring water in a water tank
« Reply #73 on: January 08, 2013, 12:34:24 am »
This has already been discussed. The cheapest diff press sensor in Australia is $575. I agree that a 4-20ma sensor would be best but I have 5 of these tanks to monitor.

Have you checked the MPX sensors from Freescale?

Greetings,

Chris

Yeah - couldn't find one with a waterproof membrane on the sensor face. If I did go down this path I would want a 4-20ma sensor as well so that I could change the architecture of the design a little bit. With 4-20ma sensors you dont get voltage drop on long cable runs from sensor to micro controller.

These are the Australian sensors that I have considered but the cost is just too high when I have a number of tanks to measure:
http://anadexlabs.com.au/shop/catalog/Water-depth-probes-orderby0-p-1-c-272.html

« Last Edit: January 08, 2013, 12:42:30 am by ilium007 »
 

Offline mamalala

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Re: Measuring water in a water tank
« Reply #74 on: January 08, 2013, 12:45:04 am »
This has already been discussed. The cheapest diff press sensor in Australia is $575. I agree that a 4-20ma sensor would be best but I have 5 of these tanks to monitor.

Have you checked the MPX sensors from Freescale?

Greetings,

Chris

Yeah - couldn't find one with a waterproof membrane on the sensor face. If I did go down this path I would want a 4-20ma sensor as well so that I could change the architecture of the design a little bit. With 4-20ma sensors you dont get voltage drop on long cable runs from sensor to micro controller.

Hmm, are you sure? For example, look at the MPX5700A, this is an absolute sensor in the unibody package. If you look in the datasheet for that sensor:

http://cache.freescale.com/files/sensors/doc/data_sheet/MPX5700.pdf?pspll=1

On page 4 you can see the construction of that unibody package. The pressure side is internally covered in a silicone coating. P2 is not coated, but for the absolute sensor you can glue that onto a metal sheet to seal it off, for example.

Other unibody sensors are constructed the same, IIRC. It's not that complicated to attach some simple circuitry that in turn will give you a 4-20 mA output. Or you put a small ┬ÁC locally and give it a RS485 interface. You can then cover that circuitry in silicone as well to seal it all.

Just an idea.... Since samples are available, i think it's worth a try.

Greetings,

Chris

Edit: I picked the 5700A rather randomly. Dunno what pressure range to expect in your tanks.
 


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