Measuring differential-pressure -1000 Pa - 0 + 1000 Pa at a high sampling-rate (1000 samples/sec)

Using Arduino Project Guidance
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Hi everybody, I want to measure and log the change of the differential pressure over time in short timeintervalls. Now the words "fast" or "short" do not specify numbers so here are the numbers I want to achieve.
Measuring differential pressures that can go above and below a reference-point that has ambient-pressure in the range of

  • 0 to -1000 Pa which means a pressure below reference. Minus 1000 Pa and
  • 0 to + 1000 Pa which means a pressure above reference. Plus 1000 Pa

Short timeintervals means a measuring once every millisecond = 1000 measurings per second. 1000 samples per second. Resolution of the ADC 10 bit or 12 bit

I have done some initial measurings with a differential sensor from sensirion type SDP6xx. This sensor has two disadvantges: the sensor has a I2C-interface and uses a dynamic measuring principle. Dynamic means the air is really flowing through the sensor. If a hose with a small diameter (2mm) is used the pressure-drop caused by the air flowing is significant even with a hose-length of only 20 cm.
1000 samples per second.
I'm willing to use an external ADC with SPI-interface if this ADC is really fast. And I'm willing to use a microcontroller with a lot of RAM like a Teensy 4.0 to be able to store a lot of samples.

The final purpose of this project is to measure the changes of the pressure in sewer pipes when 10 liters of water fall down a vertical downpipe. In sewer pipes when 10 liters of water fall down a vertical downpipe This falling down causes pressure fluctuations that can be so great that a siphon is sucked empty by the low pressure inside the pipe. I want to record the pressure inside the sewer-pipe over time with a high time-resolution 1000 samples per second.
This Sensirion SDP6xx-Sensors are too slow. So I'm searching for a measuring technology not too expensive. In the range of around 100 Euros that is fast enough.

One idea I have is to use an optical sensor with a single line of pixels and these pixel look at a inclined tube manometer which is filled with black water. I have no idea if this will be fast as 1000 samples per second and if whether due to the inertia of the water the water column will follow the changing pressure fast enough. But it will be interesting what perfomance this measuring system will have.

So does anybody know of such a photo-linesensor? The other basic approach would be a differential pressure-sensor for the range of 0 to +-1000 Pa with analog output connected to a fast ADC.

Or a differential-pressure sensor with SPI-interface. I'm open to totally different approaches and if you know of a sensor with a range only 0 to + 200 Pa or 500 Pa. I Will consider this option too.

Maybe even measuring the water-level in a "probing-siphon" with an optical distance-sensor that has a high sampling rate might be a way. As this is what is happening the sewer-pipes: sucking a siphon empty through the pressure-fall.

best regards Stefan

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what will you do with the data ?

(if that happens, you need to add either an anti-siphon valve (horizontal piping) or a membrane aerator (vertical piping) in between your siphon and whatever tube is causing the "sucking" effect.)

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I will use the measured data as empirical data what can happend in education how the pressure goes up and down.

I haven't mentioned this yet.
There is installed a membrane aerator at the top of the vertical pipe.
As far as the manufacturer of the membrane aerator says in his application-notes the diameter of DN50
= 50 mm of the membrane aerator is sufficient for two toilets and a height of the vertical pipe of 10m.

But I experience that a siphon in a flatbed shower which has only about 30 mm "siphon-height" is sucked empty. I did some tests with leaving the vertical pipe completely open. Then the shower-siphon is not sucked empty. But this would mean to have the bad smelling of the sewer-pipes inside my toilet if the vertical sewer-pipe is permanently opened.

This means the membrane aerator opens only if a certain pressure-difference is present. And this pressure is high enough to suck the low-height shower-siphon empty.

I'm interested in measuring the pressure changes with membrane aerator and without membrane aerator = completely opened.

And I want to test different brands of membrane aerators and different sizes.

I know there are aditional things you can do to avoid too high underpressure like circular-piping that air can flow from a second path to avoid to low pressure. But this would mean to open walls and floors. I decided that opening walls and floors is too much effort. I can live with a occassionally empty sucked siphon in the shower.

Another thing I want to - at least test - is a motorised valve that opens as soon as you push the water-flush button of the toilet.

best regards Stefan

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OK - cool scientific exploration - bad smelling from the sewer-pipes is indeed a bad thing...

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