C7195A Water Flow Sensor
Manufactured by Honeywell

Original report by Marta Lwin

The C7195A water flow sensor, is a mechanical water flow sensor with a rotating turbine. The turbine supports a magnet which rotates in front of a Hall effect sensor (more info about the very useful Hall sensor: http://en.wikipedia.org/wiki/Hall_effect). The hall sensor measures the field of the magnet giving an output directly proportional to the water flow. The output can be processed by an electronic controller.


Typically used to measure the Domestic Hot Water (DHW) flow rate in domestic appliances The output of the sensor can be used to modulate the burner load or open heat demand in a boiler.

Electrical Characteristics

water flow sensor link: datasheet here.

Electrical data

The minimum operating flow rate is 1.5 liter/min or lower

The nominal voltage (V00) in 12 V but it can go to a max of 18 v The current is 10 mA

The output is <0.4 V

I have a lot of fuzzy understanding of this area of the schematic.

The electrical changes when the sensor senses the flow of water:

Pin Descriptions

The pins: the is a variety of choice with the electrical connections for the models available and described in the data sheet. Below is the image of the model best used with a micro controller and bread board.

Micro-controller Connections

The sensor is attached to a water pipe, it sends a modulation output to the micro-controller, Using a pic processor, the output can be used in a graphic output.

Application Notes

I was intrigued by the possibilities of this sensor as an direct read out of use in the house hold. I envision linking this sensor through a microcontroller to a graphic output which depicts the water resources used by a household in an imaginative manner.