My lab uses a home-built biomedical instrument that acts as a ventilator for test-subjects. In other words: our device combines nitrogen and oxygen gases and pumps them down the line at a specified rate. The actuation is controlled with three parameters: breath rate (breaths/min), inhalation duration, and breath hold duration. While it is running, it considers these parameters and actuates accordingly.
In order to calibrate our device, we have regulators on each gas line that control their pressures. This obviously changes the gas volume output at the end of the line. What is an easy way for us to measure the volume of gas flow out of the system? I'm trying to avoid buying any devices if I can.
This device is very low output, approximately 0.25 mL/breath or ~40 mL/min. I had originally thought to use a small syringe, but the backpressure was too much for the ventilator.
Our current method for measuring volume output is to fill a bucket with water, place a water-filled graduated cylinder on the surface, and then have the ventilator actuate several times to displace the water in the cylinder, measure that, and then divide by the number of actuations to get volume/breath.