You cannot use the ATMEL micro-controller it is clearly stated on the data sheets that is it not for any sort of health care or life safety.
the Phillips sensors is NOT ACCEPTABLE in ANY way.
You have to use a true DIFFERENTIAL PRESSURE sensor that measures the pressures across the wall.
in the US, it is about 0.002 inches of water.
the BME280 is an absolute pressure sensor and the manufactures listed error is more than that.
the rule of thumb is that your sensor should be able to resolve 10 times more sensitive than your monitored point.
if you want to measure 0.03" you should be able to resolve to 0.003"
Pressure sensor
RMS Noise
Sensitivity Error
Temperature coefficient offset
0.2 Pa (equiv. to 1.7 cm)
± 0.25 % (equiv. to 1 m at 400 m height change)
±1.5 Pa/K (equiv. to ±12.6 cm at 1°C temperature change)
the noise is equal to 0.004" water that is your error starting point and is already at the critical point.
second, the BME is a single point, so you need one in each space and they would both have to be calibrated.
second, you would have to verity that the temperature of the sensor does not affect the reading. just one side getting warm could make the pressure invert.
Second, what is the worst case scenario of the pressures do invert ?
do you have contaminants infect the people inside of the room ?
do you force the contaminates to be expelled from the room ?
imagine if the researchers were a little more careful..
an estimated 36.9 million people are living with HIV today
I do not know if it was released by a simple reverse flow in a clean room, but there are other things that are more toxic.
When we did pharmaceutical production clean rooms, the cascade pressures from the exterior to the core area dropped as each level. an inversion of pressure would contaminate the entire facility. the one time there was an inversion it was due to a maintenance error and the re-certification along with the disposal of all the product was well over 500 mil. USD.
The research facility that had a similar accident is still patrolled with armed guards and when you gown up and enter, you sign that you know you will be shot and killed, then incinerated, if you violate the containment barriers. you get a tilt radio. in case you die inside and fall over, the radio tilts and alerts those outside where to get the body.
I would say that you do not need to monitor the pressure, but spend the money to create the proper air flows for the environment. the sensors are only there to document.
Lastly, the tubing that connects to both sides of the differential pressure transmitter are to be considered contaminated and a path that penetrated the theoretical barrier.
Go to a company that does this and is well staffed with qualified engineers.
make sure that the sensors you buy can be certified and calibrated with NIST traceable equipment.
As a note, here in New Jersey, we have more than a few Super-Fund sites that were making some really nasty stuff.
This is not casual engineering, nor the realm of hobbiests.
in my view it would be safer to tell a noob how to connect an Arduino to a 4,000 volt AC panel.
