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Can anyone help to the project i intend to develop? I want to have a water pressure gauge in a long pipe used for irrigation in a field. This pipe does not exceed 6bars of pressure. What i want to do is read pressure signal in raspberry and if i have a big change (for example when the pipe breaks and we have leakage) it should send me an sms in my mobile phone.

So what i need is:

  1. Pressure sensor
  2. GSM module
  3. Battery (since it will be outside)

Do you have any suggestions on what components i need for this project? The difficult part is the pressure sensor i think. I did some quick research and the closest thing I found was this honeywell gauge ... dp/SN35336

My concerns. Since the pipe irrigates a field, 6 bars is normal. 5-6 bars in reality. The problem with having many flow meters spread across the pipe network is that you have to power each flow meter and you have no electrical source close. Also, it will be outside and prone to be stolen. In the scenario of a manometer it will be in one place which will be covered and protected with power source close.

What do you think about this product: http://gr.rsdelivers.com/product/honeywell/nscdann100paunv/absolute-pressure-sensor-for-gas-liquid-100psi-max-pressure-27-65-v-dc/8536803.aspx

And what about GPRS module. I have no idea what is on the market. I searched and found some solutions but a good advice from someone who has used one would be appreciated!

Now look at my concerns. Since the pipe irrigates a field, 6 bars is normal. 5-6 bars in reality. The problem with having many flow meters spread across the pipe network is that you have to power each flow meter and you have no electrical source close. Also, it will be outside and prone to be stolen. In the scenario of a manometer it will be in one place which will be covered and protected with power source close. I have no idea what is on the market. I searched and found some solutions but a good advice from someone who has used one would be appreciated!

Dimitrios Evangelopoulos
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1 Answers1

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Sorry, we do not do product recommendations on Raspberry Pi exchange.

You are on the right track.

GSM

You can buy any GSM module that has SPI or UART. The cheaper the better you just need to send SMS, doenst have to be a 3G or 4G one! ANy cheap eBay one. They usually use UART (Serial Console) some are SPI but a USB one would be good?

SIM CARD

Find a security sim card. You top them up for example 10EURO and it lasts over a year. You can only send SMS on them, or only GPRS and they work on any network. So if it gets stolen nobody can use it.

PRESSURE SENSOR

The pressure sensor for 100PSI (NSCDANN100PAUNV) should work fine. It is a bit pricey at 30Euro but it seems like the good one. I would search a bit more I am sure there are cheaper ones for maybe 10PSI/20PSI from the same company.

The problem with these sensors that are Analogue. You will need an A2D chip (analgue to digital) becasue the Pi cannot read Analogue. Basically how it works is that 0PSI is probably 0Volts (0% Input Voltage) and 100PSI is maxVolts (100% of input voltage) Because 6PSI is only 6% of 100PSI its difficult to detect edge using some resistors and other tricks.

BATTERY

The size of the battery depends on the circuit wattage used. It defiantly cannot be 4xAA batteries.

Lead crystal batteries are good but you would probably need a car sized one to last a decent 4-6 months without having to change it every few weeks.

POWER CONSERVATION

You could use "Hall Effect Water Flow Meters" because they basically do not use any power. They get activated by a switch from a magnet.

Pressure gauge is not to bad power usage but its still power used when you dont need it.

Do not have GSM power on always. Have a switch to turn it on when you need to send SMS.

Raspberry Pi. You would have to go for the A model and disable allot of stuff to get down to hundreds of milliAmps usage. Its doable though.

Solar panel? You can charge the battery using a small panel or wind propeller?

If you want to run on AA batteries, you cannot use Rasberry Pi. You would have to go to Arduino or PIC programming and circuit creation. With these things you can use a small battery pack (like NiCD used in RC racing) that could last 6-12 months.

Piotr Kula
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  • I thought 6PSI was 6 bar. Pretty much not a pressure problem then – Piotr Kula Jul 21 '16 at 09:41
  • Are you looking for product recommendations? We don't really do that here. You can buy GSM modules and batteries on ebay. The question maybe is what size battery, but that is not Pi specific. – Piotr Kula Jul 21 '16 at 09:43
  • ppumkin check my answer below. i posted as an answer because it was big for comment. – Dimitrios Evangelopoulos Jul 21 '16 at 09:48
  • If you could tell me some possible products it would be nice. but if this violates the rules of stackexchange, it's ok – Dimitrios Evangelopoulos Jul 21 '16 at 09:49
  • I changed my answer. Sorry- I cannot put specific products in. I can only guide you to your own choices – Piotr Kula Jul 21 '16 at 09:53
  • It's ok. your answer is very helpful. Can you take a look at the link below? Do you think this will work for me? – Dimitrios Evangelopoulos Jul 21 '16 at 09:57
  • Yea. just updated again. That sensor is good for 100PSI - you just need A2D (analogue to digital convertor) because Pi cannot read analogue. – Piotr Kula Jul 21 '16 at 10:03
  • PS If you find any answers helpful on this site, please upvote them with the up arrow on the side of the posts. This gives thanks to people contributing. Please search other articles on this site, there allot of good ones. I also wrote a good one about batteires, you can search my answers for this. – Piotr Kula Jul 21 '16 at 10:05