I'm looking for advice on how to set up the following system or if it possible at all?
I'm using a cyclic pump as shown in the image and want to see the current airflow data on a display. The pump is simple consisting of a reciprocating piston inside a cylinder with an outlet on the end. Air is pushed in and out of the outlet as the piston moves back and forth.
I would like to read the flowrate at the outlet in the 'sensor 2' position. the flow will vary from 0 to +60 and 0 to -60 Litres per minute max (depending on piston direction). The plan is to display this flow data on a display beside the pump - the waveform should look like a series of zigzags (WWWWWWW), and have it updating in real time as the pump runs.
the second sensor, possibly in the 'sensor 1' position needs to measure the number of cycles per minute (distance sensor?). Ideally it should also be able to measure the duration the piston is moving in each direction as the sometimes the piston is not moving at the same speed in each direction. The maximum number of cycles per minute will be 40 cycles per minute. The number of cycles, duration of extension and duration of retraction, all need to be displayed also.
Because there’s a known direct relationship between the piston volume and airflow, it may be easier to measure the piston / motor activity to measure the volume of air being displaced.
The only significant unknown variable becomes compression of the air, but I’m sure a constant can be applied after some initial testing.
yes that's a good point. I'm Interested in volume more than flow and have been using this method to set my total volume output (setting the appropriate stroke length).
in this case would it be possible to read everything from some type of high resolution distance sensor? could I build a set up to a calculate the volume based on the stroke length from any points in the cylinder (that the piston could change direction anywhere) or would it need a 'home' reference point.
Also the display reading could lag the system or show the previous cycle as long as the readings are accurate.
All sorts of ways to measure travel, from a precision optical or linear encoder or something as simple as pulse counting on a stepper. Depends a lot on mechanical specs & fitment. Stepper or incremental motion on plunger gives direct relationship to minimum step size an volume. Zero sensor is needed to calibrate, overtravel limit is good idea if runaway can cause damage.
Volumetric mass flow sensors can be very precise answers on flow but at a massive cost depending on pressure regime & gas.
Speaking of gas, different gasses act differently from room air. Is this a factor?
