FR2475694A1 - Liquid fuel burner feed safety shut off - has pressure switch in fuel overflow return pipe which actuates safety valve on burner - Google Patents

Abstract

The fuel is stored in a drum (1). The fuel is pumped out of a tank by a pump (6) connected to the tank by a pipe (3) through valves (3,4). Excess fuel is returned to the tank by an overflow pipe (9). The main flow goes from the pump (6) to a burner (5). The pressure of the return flow is controlled by a pressure switch (10) with contact points (11). The electrical circuit is made up of a cell (12) and a safety control box.

Description

 The present invention relates to safety against the risk of leakage which may occur on the hydraulic pipes connecting a transfer station, or a burner with mechanical fuel oil spraying, to a storage tank.

The known devices are very specific and must be added together, to obtain maximum protection on the soft piping, suction and return, on the pump used for the operation of the mechanical spray burner, as well as in installations with transfer pump.
The device, according to the invention, causes the burner to stop mechanical pulverization, a few seconds after the appearance of a leak, anywhere in the circuit, pump or suction or return pipes, thus avoiding fuel oil. spreading dangerously at the point of leakage. Similarly, on an installation with transfer pump, the device, according to the invention, allows the pump to stop 1 a few seconds after the appearance of a leak on the pipes of 'suction and discharge or on the pump itself, or by lack of liquid & transfer, thus avoiding the destruction of said pump. by dry running resulting from the exhaustion of the tank.

 The device, object of the invention, comprises a means of braking the flow of fuel, at the open side end of the return pipe, in order to artificially create a slight overpressure in this entire pipe. According to an embodiment of the invention, this means is a needle screw valve designed to allow adjustment of the liquid flow rate, without however ever being able to stop it completely.

 Then a detection means will transmit the effect of this overpressure to the safety boot of the mechanical spray burner. according to an RS of the invention, this means is a pressure switch adjustable from 0 to I bar which can be placed anywhere in the return pipe, according to the requirements of each installation. By its very precise adjustment, as well as by the adjustment of the needle screw, is obtained the engagement of the contact of this pressure switch upon the appearance of a slight overpressure.

This contact will be electrically connected in series with the cell which is part of the normal ########### control circuit of the appliance, and the said contact will thus act on the safety boot of the burner
The appearance of a leak anywhere in the hydraulic system will cause the pressure switch to drop, and the cell circuit to break through its contact. This break of more than 16 seconds will stop the operation of the burner and its pump, stopping the flow of fuel oil in the pipes, and consequently stopping the flow of liquid at the point of leakage, with limitation of all possible consequences.

 This time delay, of approximately sixteen seconds, existing on all the models of safety boots, allows easily the overpressure of the ca @ alisation at the instant of each start-up of the burner, and thus, by closing the contact. of the pressure switch, allows continuity of operation.

According to another embodiment of the invention, it is only the function
operation of a hydraulic transfer pump which is controlled with the
safety boot originally intended for burner operation
with mechanical spraying. In this case, the control circuit cell
is replaced by a resistor of equivalent average value.
sostat being installed on the discharge line, and according to the
same principle as before, thanks to a slight constriction of this
pipeline, closing the pressure switch in less than 16
seconds is largely obtained after start-up, thus authorizing
continuity of operation1 ensuring in particular that the pump
rotation in liquid medium, avoiding its deactivation which would occur
fairly quickly if it should run dry
The accompanying drawing illustrates, by way of example, an embodiment
of the device according to the present invention: as shown, the
fuel from tank 1, sucked through line 2, fitted with a police valve @
3 and a direct flow valve 4, arrives at the burner 5 via
diary of its pump 6; the excess fuel oil is returned to tank I by
the return line 7, fitted with a non-return valve 8 and the tap
flow brake screw needle 9 * The low pressure obtained in
this return piping 7, largely I6 seconds after putting into operation
te of the burner 5, and during all its normal operation, is transmitted
by the tee 9 at the pressure switch 10, thus closing its contact 11 ;; G e 1 yes
ci, connected in series with cell 12 via the 2 electric wires
triques I3 and 14, normally restores the an bot control circuit
tier of sequence 15 of burner 5, and ensures the continuity of its function
operation. If by costre, an incident or leak occurs at a point
any of the hydraulic circuit, there is a drop in pressure
which discharges the pressure switch IO, which by its switch 11, cuts
then the current in the safety boot, which has the effect of
immediately rotate the pump operation.

The device which is the subject of the invention can be used as a supplement
important for the safety of people on all installations
heating, industrial or domestic, using pulp burners
mechanical fuel oil control, supplied by suction pipes and
return, with or without tank in charge with or without nurse and transfer pump

Claims (7)

I - Safety device, allowing the stopping of a transfer pump or supply of a burner with mechanical spraying of heavy oil, a few moments after the appearance of a fault at any point of the installation , either lack of liquid to be transferred, damage to the pump, or leak on one of the suction or return pipes. This device is characterized by the fact that it comprises, connected to the end of this tank of the return pipe, a means of braking the flow of liquid, in order to slightly increase the pressure in this whole pipe; then permanent detection of this overpressure by a second means actuating a contact electrically connected in series with the cell of the control circuit of the burner safety box: the opening of this circuit, due to a lack of pressure from one duration greater than the time delay of the safety boot, causes it to trip, therefore stopping the supply pump.  2 -A device according to claim 1, characterized in that the means intended to slow the flow, is a calibrated orifice.  3 - Device according to claim 1, characterized in that the means for limiting the flow is an adjustable orifice with a needle screw designed so that it can never be closed completely. tion and discharge mounted on the tank. means intended to slow the flow can be included in the deapira- block 4.- Device according to claim 1, characterized in that lo  5 - Device according to claim 1, characterized in that the  means for detecting overpressure is an adjustable pressure switch  be placed anywhere in the return line  6 -A device according to claim 1, characterized in that the  means of cutting the control circuit, driven by the pressure switch, is a leter-  classic mechanical breaker.  7 -A device according to claim 1, characterized in that the means  while cutting the control circuit, driven by the pressure switch, could be waterproof mercury rocker, usable in application of the device with  highly volatile or flammable fluids.