These two SUNTEC AUV models are specially designed for the replacement market : they replace the majority of one-stage pumps on the market of which most SUNTEC AS 47, AL 35, ALE 35 references. They incorporate a blocking solenoid valve fitted with a built-in return valve ensuring an in-line cut-off function and a nozzle line pressure relief. They feature two nozzle possible outlets.
The gear set draws oil from the tank through the built-in filter and transfers it to the nozzle line via the cut-off solenoid valve. A pressure regulating valve is used to dump all oil which is not required at the nozzle.
In two-pipe operation, the by-pass plug fitted in the return port ensures that the oil dumped by the regulating valve is returned to the tank and the suction line flow is equal to the gear set capacity.
In one-pipe operation , the by-pass plug must be removed and the return plugged, so that the oil which does not go through the nozzle line is returned directly to the gear inlet and the suction line flow is equal to the nozzle flow.
The solenoid valve of the AUV pump is of the “normally closed” type and is situated in the nozzle line. This design ensures extremely fast response and the switching can be selected according to the burner operating sequence and is independent of motor speed.
When the solenoid is non-activated, the valve is closed and all oil pressurized by the gear set passes through the regulator to suction or the return line, depending upon pipe arrangement.
As soon as the solenoid is activated, oil passes to the nozzle line at the pressure set by the pressure regulating valve.
Caution: The non-used nozzle outlet must be loosened, thoroughly bleeded and retightened, to obtain a perfect cut-off function.
Nozzle line pressure relief (for nozzle incorporating a cut-off function)
The nozzle line pressure relief function operates only when the installation is fitted with a nozzle incorporating a cut-off function which opens at 4 bars or above. Any subsequent expansion of the oil due to residual heat from the preheater or the boiler is discharged through the relief valve in the pump which opens at a lower pressure than the nozzle opening pressure.
Note : For a boosted pump, the overpressure applies to the safety shut-off device and the relief valve.