Question : where to find FlowMeter Pulse/Liter

[hallard]

May be stupid but I would like to know how do you know (or calculate) number of pulse by liter in your sensors definition

// Sensor Type
// -----------------------
// YF
#define YFS201	450
#define YFB1	660
// OF
#define OF10ZAT	400
#define OF10ZZT	400
#define OF05ZAT	2174
#define OF05ZZT	2174
//------------------------

Did you calibrated somewhere or measured it?

Looking at datasheet I can't find anywhere where is the number of pulse by liter.
YF-S201 datasheet does not mention anywhere.

Thanks