Air Pressure Equation for DIY Pressure Sensor

[scabsareus]

Hi I was wondering,
I have a project in college where i am asked to make a sensor of some sort, i then proceded to make plans and decided on a pressure sensor, i have looked everywhere for an air pressure equation that i could use involving the density of air and the volume of the pvc pipe i will be using, basically some water will rise into the pvc pipe and create pressure by pushing the air into an airtight compartment that will then in turn continue to push up a contact resistor attatched to a buzzer (ratios of the decibels will be read and i will make ratios of decibels to air pressure) to put it simply.
If anyobne has a clue please respond
thanks

 

[scabsareus]

i have found that pascals equation might do it, involving volume, density of the air and temperature.
but i still can't find the arrangement, does anyone know?

 

[huan.conchito]

wan der waals equation will be more prescise...

 

[scabsareus]

thanks man, that might just do it, i will have to verify that with my teacher, if there asre still less length equations could anyone tell me but I am sure this should do fine

 

[scabsareus]

less lengthy*
bad typing