Pulse counter

A method for counting fluid pulses using a pulse counter comprising a first housing part, a second housing part with a fluid passage, the first housing part separate from the second housing part, a circuit board at least partially enclosed within one or both of the two housing parts, the circuit board comprising a light pulse transmitter and a light pulse receiver, a battery at least partially within one or both of the two housing parts, the battery supplying electric power to the light pulse transmitter and the light pulse receiver, a rod slidably arranged within the first housing part and the second housing part, with one end of the rod within the fluid passage, and a second end arranged to at least partly break a path for a light pulse between the light pulse transmitter and the light pulse receiver any time a pressure within the fluid passage exceeds a threshold, and a spring forcing the rod away from the light pulse and towards the fluid passage, the method comprising:

• setting a required the pressure level to move the rod into the path by setting the force of the spring and by selecting a diameter of the end of the rod within the fluid passage.