The SUNTEC ATUV oil pump is specially designed for the replacement market : the ATUV replaces the majority of two-stage pumps on the market of which most SUNTEC AT245, ATE245, models; it also can replace AT255, ATE255 models used with nozzles up to 5 GPH. It incorporates a blocking solenoid valve fitted with a built-in return valve ensuring an in-line cut-off function and a nozzle line pressure relief. It features 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. Pressure regulation is assured by two spool valves, one for each pressure mode.
Switching between low and high pressure is assured by a “normally open” by-pass solenoid valve. When this solenoid is non-activated, a by-pass channel is open, allowing the normal functioning of the low pressure regulating valve which sets the nozzle pressure. When this solenoid is activated, the by-pass channel is closed, thus pressure will build up on both sides of the low pressure regulating valve eliminating its effect, and the high pressure regulating valve now determines the nozzle pressure.
The blocking solenoid valve of the nozzle line is of the “normally closed” type.
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 this solenoid valve is non-activated, the valve is closed and all oil pressurized by the gear set passes through the regulators to suction line.
As soon as this solenoid is activated, oil passes to the nozzle line at the pressure set by the pressure regulating valves.
Bleeding in two pipe operation is automatic (it is assured by a bleed flat on the piston of the low pressure regulator). It may be accelerated by opening the pressure gauge port.
Caution: The non-used nozzle outlet must be loosened, thoroughly bleeded and re-tightened, to obtain a perfect cut-off function.
Nozzle line pressure relief
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.