Method of sensing and indicating errors in a dosing circuit

Claim 1

Method of sensing and indicating errors in a dosing circuit, in which a pumping device (1) pumps fluid via a conduit system (4) out to at least one dosing device (3) located nearby a dosing place, which measures and discharges intermittently a predetermined volume of the fluid through a pressure controlled non-return valve (16) out to the dosing place when the pressure in the conduit system (4) is increased from a low pressure to a high pressure during a certain limited time, the dosing device (3) comprising an inlet and an outlet (8, 9, respectively) for the fluid, a charging chamber (10) connected to said inlet (8), a dosing chamber (11) connected to said outlet (9), a closable passage (12) connecting the chambers and a moveable body (13), which on one side thereof is subjected to the pressure in the charging chamber (10) and on an opposite side thereof is subjected to the pressure in the dosing chamber (11) and upon an increase of the pressure in the conduit system (4) to said high pressure moves in a way such that the volume of the dosing chamber (11) decreases and the volume of the charging chamber (10) increases, during which moment the passage (12) between the chambers (10, 11) is closed, whereby the fluid is discharged out of the dosing chamber (11) through said outlet (9) and non-return valve (16) to the dosing place and fluid flows into the charging chamber (10) from the conduit system (4), said moveable body (13) being moving in an opposite direction upon a decrease of the pressure in the conduit system (4) to said low pressure by the force of a resetting device (14), thereby pressing any fluid located in the charging chamber (10) through said passage (12) into the dosing chamber (11), and a valve (15) being arranged to prevent outflow through the inlet, characterized in that an error in the dosing circuit is sensed and indicated by: (a) measuring the pressure in the dosing chamber (11) and channels between the same and non-return valve (16) connected thereto, (b) measuring the time at least while the dosing is taking place, from a chosen reference time during a dosing cycle, (c) checking that a combination of simultaneously measured values of pressure and time is kept within predetermined limits for such a combination, and (d) emitting a signal when the combination of measured values is not kept within said limits.