Hello all,
I am designing a system that can test a rubber tube to fatigue failure.
This pipe will be inflated up to 10 bar (this can be regulated to 9). This pressure is held for 10 seconds then dumped, adding 1 to the counter.
The current system must be monitored by eye to see when the tube bursts, and I wish to design something that stops the counter when the tube is burst.
My current thought process is to use the same system, but fit an air pressure sensor between the air inlet and the tube, this should read my air pressure and feedback to the arduino. Then if this value is too low it would indicate a burst tube and subsequently stop the counter.
I have not purchased any equipment for this and would appreciate some guidance on what air pressure sensors would be best. I would like to use this air pressure sensor https://uk.rs-online.com/web/p/pressure-sensors/3748799/ but have not used air pressure sensors in my applicances like this before and would value some guidance.
Thanks in advance.
The sensor should work .
I would suggest you consider a 15 bar if available. Unless at no time will you ever exce10 bar.
I would assume that you will See a rapid decrease in pressure upon a burst.
You can use max()
To record the pressure for each run.
And catch the burst pressure.
You could automate the count as well.
If the pressure now is 5 bar less than 5 seconds ago. Increment by 1
That would count both Normal up and down as well as burst events.
Any uno or nano can do this
That sensor has a relay output telling whether the pressure is above or below the set value. It does not give the pressure value.
A burst will make a loud bang will it not? Detect it with a microphone and VOX circuit.
I had toyed with this idea, however the tube supplies a mask which uses a dump valve, this sound itself is also very loud so I don't think this would be as accurate as air pressure.
But I will still have a look at this if I can find a sensitive microphone laying around.
Railroader:
That sensor has a relay output telling whether the pressure is above or below the set value. It does not give the pressure value.
How easy would it be to keep this sensor in line with the tube and it's inlet?
I am planning to set the value to an assumed value that could not be reached if the tube had burst.
My thoughts are that there should be a vast difference between an intact tube and a burst tube. So long as the relay output is detected it will add 1 to counter.
dave-in-nj:
The sensor should work .
I would suggest you consider a 15 bar if available. Unless at no time will you ever exce10 bar.
I would assume that you will See a rapid decrease in pressure upon a burst.
You can use max()
To record the pressure for each run.
And catch the burst pressure.
You could automate the count as well.
If the pressure now is 5 bar less than 5 seconds ago. Increment by 1
That would count both Normal up and down as well as burst events.
Any uno or nano can do this
This sounds like what I'd like to try.
Here is a simplified flow of what I want it to achieve:
- Compressed air input and held for 10 seconds
- Air pressure sensor returns either burst or NO burst condition (against parameters)
- IF NO burst, add 1 to counter and deflate (then repeat from 1)
- IF burst condition detected, stop counter and stop inflation.
I just don't know how to connect the air pressure sensors to my arduino, I'm not familiar with them and cannot find an example of connecting a relay output like this to my uno. Will I need a motor shield or separate board?
Thanks in advance.
In some way You need to know the difference between a powered and burst tube, and the test cycle being depreassured.
To measure pressure linearly You need an analog pressure sensor.
the link you had was for a switch.
this is analog so will be better suited for testing purposes
PRESSURE TRANSDUCER
takes 5 volts and outputs 0-5 volts.
this could be powered from your Arduino. it uses 10mA, very little
you feed it to an analog input and Bob's your Uncle.
very easy.
code is in the IDE as an example if you just use the POT example.
dave-in-nj:
the link you had was for a switch.
this is analog so will be better suited for testing purposes
PRESSURE TRANSDUCER
takes 5 volts and outputs 0-5 volts.
this could be powered from your Arduino. it uses 10mA, very little
you feed it to an analog input and Bob's your Uncle.
very easy.
code is in the IDE as an example if you just use the POT example.
Thank you very much for your help, I have ordered both types just to have a play around with.
I'll update when I make some progress!
Hi,
I am designing a system that can test a rubber tube to fatigue failure.
This pipe will be inflated up to 10 bar (this can be regulated to 9). This pressure is held for 10 seconds then dumped, adding 1 to the counter.
The current system must be monitored by eye to see when the tube bursts, and I wish to design something that stops the counter when the tube is burst.
If you do not need to log the pressure, only the number of times its inflated, when the tube bursts it cannot be inflated again so the count stops.
Is that what you need?
Do you deflate all the way back down to atmospheric pressure?
Do you have to deflate all the way back to atmospheric pressure?
If you don't need to go all the way down to atmos, then have it drop to say 0.25Bar Gauge and reinflate, have a pressure switch that is set for 0.1 Bar Gauge.
When the tyre explodes the tyre pressure will drop to below 0.1Bar Gauge and you stop the count and the pressure cycle.
An adjustable pressure switch will be cheaper than an electronic pressure unit.
Tom... 
the IDE offers both a serial output in numbers as well as a graphing output.
you can also save data to an SD card and even to a spreadsheet
I think that just monitoring the pressures a few times will reveal the information needed to help you know how to write the program.
I assume that you will see the pressure ramp up and fall as a normal, but on failure the rapid depressurization will give you a very clear point to say there was a catastrophic failure.
i my mind, a pressure up, then down completes one cycle.
if the failure occurs on a cycle, it is still a complete cycle,
you might have 4 good cycles and the failure on the 5th.
the counting would not really matter all that much as you say it differently.
there were 4 good cycles, then a failure.
if you plan to keep the Arudino connected to a PC for the visual, that offers some benefits.
adding a simple display, even the tiny display would offer an ease of seeing what is going on. OLED
as a note, you can play with the POT example and get some practice on playing with analog and the values and the data and such.
Take a look at the honeywell ABP series pressure sensor. They are available in analoge, I2C, or SPI, there are multiple libraries available, and they can handle pressures up to 10 bar. They are also quite inexpensive, costing around EUR 15.00.