Arduino to measure temp, pressure, liquid level (and report to network)


I am working for a small systems developer and electronic prototyping house in Hong Kong and I am new to the world of Arduino. I don't even own one yet (while I've been looking at the available versions for quite a while).

I am now using an expensive (too expensive in fact) data acquisition system to measure temperature, pressure, liquid level (and flow rate) in a couple of dozen machines. It's all been put together in a rush and the wiring is a mess. As a backup I am using inexpensive temperature controllers for temperature alarms (ie. switch relay if temperature of 50C is exceeded).

I am now looking at replacing all of this mess with one Arduino on every machine. And connect them using standard LAN wiring.

The sensors are off the shelf and not too expensive:

The K-type thermocouples I am using now only cost a few dollars since we don't need it to be too accurate, and I am looking at replacing them with the LM35DZ or DS18B20. I've been experimenting with them for a while.

For liquid level I am using the eTape, which is in fact the most expensive part (well, maybe except the DAQ system from National Instruments and their expensive software which I am still using in trial mode).

For pressure I have both on board, the MPXV7025 pressure sensor, which can show from about -3 to +3 PSI, and the MXP2100 which is from slightly above 0 PSI to almost 15 PSI. I'd prefer the MXP7025 for low cost and ease of use and the fact it gives me negative pressure, but unfortunately it requires one of the ports exposed to the outside of our tanks (which has a lot of down sides).

For the software side of things I will have to do some reading first what will be possible with the Arduino platform. Optimal would be if I could query the values by SNMP or if the Arduino would send the data frequently to a server somewhere. It would also be nice if the Arduino could act upon events, for instance if the temperature or pressure exceeds certain values it sends an SNMP Trap or it sets a digital output to high or does something else. I am really flexible but it should be not doctored.

Anyway, to cut this long story short, I will be posting here again in the near future. I'll have to select the platform and also look at what I can and cannot do with it. I may also be looking for somebody experienced (with Arduino) to put this together for me since a new project is coming up and I might be very busy again soon (btw, where could I post this "job ad" without violating the forum rules?).

All the best, Alex

Welcome to the forum and good luck with your project.

where could I post this "job ad" without violating the forum rules?).

There is "Gigs and Collaborations" in the Community section of this site that is where 'job ads' would be most appropriately posted.


The most common Arduino is the Arduino Uno.
You can add an Ethernet Shield for ethernet.
There is also a Arduino Ethernet, that has both combined.

If the code is getting large, you can use a Arduino Mega 2560.

The ethernet library is getting better and better, but it is slow and doesn’t handle bad connections as good as normal ethernet devices.
Using an Arduino as webserver (to display settings and to send commands) is possible. The examples for that are easy.

You might consider good quality 433MHz transmitters (or tranceivers).
If it is only to report temperature and pressure and so on, using 433MHz transmitters is a well known solution.
Suppose you have a number of Arduino Uno’s with 433MHz transmitters and a ‘base station’ that consists of a Arduino Mega + Ethernet Shield and 433MHz receiver.
That way you can see and control everything from a webpage.

I am not sure that Arduinos do well with lots of electrical/industrial noise, I would find a good housing to shield each one, just a thought.