diff --git a/src/FlowSensor_Type.h b/src/FlowSensor_Type.h
index 1cf8220..87e44f6 100644
--- a/src/FlowSensor_Type.h
+++ b/src/FlowSensor_Type.h
@@ -13,6 +13,7 @@
 // Sensor Type
 // -----------------------
 // YF
+#define YFD50   20
 #define YFS201	450
 #define YFB1	660
 #define YFS401	5880