Determining the flow of water in a pipe?

Question

Do it yourself

Good afternoon, colleagues! The task is to determine the flow of water in the pipe. Initial data, a vertical pipe on one side is a ball valve (no pressure), the task, with a minimum budget, is to determine that the valve has been opened and transmit information to the controller using dry signals. Unfortunately, there is no time for development and assembly.
1. The flow meter is a great thing (on the D2 pipe)
2. it is possible to put a tee and an induction one, but it’s not a fact that water will get in and it’s not clear how to bleed it from the tee
3. The petal flow sensor is excellent (but practically does not work in a vertical version)
p / s/ 24 V DC supply

Answer 1

"Fan" - a magnet on the axis and 2 hall sensors - all this is inside the pipe. You can have one if the direction of the flow does not matter. Calibrate by filling with 10 liters. It is made in 30 minutes from shit and sticks of improvised materials.

Answer 2

In the title of the question, it is required to determine the presence of water flow, in the question itself, for some reason, it is required to determine the opening of the tap. So what should be determined?
To determine the flow, there are primitive relays of the DR-P-50-20 type. You
fasten a tee with a 3/4 outlet in front of the tap and screw the sensor into it.

Answer 3

determine if the faucet is open

So maybe it's easier to put the sensor on the faucet itself? A magnet with a reed switch, for example.

Answer 4

There is no pressure (small) - it means you don’t need to fool around that your crap (pressure sensor) will break, water will beat out of leaks, etc.
50 mm - a plastic sewer pipe, or what?
Drill 2 holes (place 2 tees) - a larger one on top, a very small one on the bottom, so that later water flows out of the sensor slowly. Anything between them. For example, a float with a magnet and a reed switch. There is water - the float has surfaced, there is no water - it fell back onto the reed switch. Or a float pressing through the membrane onto the limit switch. Complete freedom of creativity.
P.S. Even a loop made of a rubber pipe - there is water - the loop is heavy, it puts pressure on the limit switch. The water is gone - DOES NOT press.
P.P.S. Let's say a purchased sensor.
https://rusautomation.ru/datchiki_urovnya/fdmh50br05x
There are a LOT of different ones.

Answer 5

It's easier to screw the level sensor into the tank than that's all.

Answer 6

Screw the relay onto the tap itself, so that when it is at least a little open, the signal does not go