next topic »

[on:]

Hi all

I am doing a special auto carbon dioxide generator. I will have calcium carbonate inside a cylindrical container and a acidic solution in an external bag. The idea is to pump the acidic solution onto the calcium carbonate via a miniature pump and on reacting, carbon dioxide will form. This carbon dioxide will cause a pressure build up inside the container and if the pressure say is more than 3 bars, I will require the pump to slow down its flow rate. And if the pressure is too low such that not enough carbon dioxide is produced, I would need the pump to pump in more acidic solution. Thus I would be using a pressure transducer and a arduino controller. May I know what are components would I need ?  Thank you.

[Reply #1 on:]

Freescale has some nice pressure transducers that look like an excellent fit for Arduino.  I have in my hands one that does about 3 bars absolute.  It outputs an analogue signal.  It's a bit small and fiddly to solder, being an surface mount part, but I am eager to experiment with it.
This one looks like a good bet for you.  Mouser has these priced at $12.
http://cache.freescale.com/files/sensors/doc/data_sheet/MPX5700.pdf?pspll=1
But many other option would be feasible.

[Reply #2 on:]

Be sure any pressure sensor you use is rated for your specific acid service. Check the datasheets carefully as most of the inexpensive ones are not and their pressure sensing barrier will not handle other then air or maybe water.

Lefty
 

[Reply #3 on:]

A kipps apparatus is used to make CO₂ this way. you might want to look into it. It autoregulates based on how much gas you take off.

[Reply #4 on:]

Thank you everyone for your spontaneous response. Actually I am a newcomer when it comes to programming and microcontroller. The pump I am using is the 2 port pumps M100-S. http://singapore.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0480188. It requires an input voltage of 3-4 V and current of 0.26-0.38 A. It has a free flow rate of 0.78 - 1.52 ml/min.

The pressure transducer we can easily find one that can measure 0-14 bars but how am I going to programme the entire system and also the connections. Do I have to use any say amplifiers or rectifiers for my electrical circuit or I can just connect literally from transducer to microcontroller and the microcontroller to pump without any other circuit.

Oh by the way we are using a Li Polymer Battery which is a 3 cell 350mAh 11.1 V battery.

[Reply #5 on:]

Do I have to use any say amplifiers

That depends a good deal on the sensor you choose.  The one I linked to will handle 7 bars absolute and reads out 0-5V analogue that you can feed directly to an analogue input.