GB2053451A - Gas burner - Google Patents

Abstract

In a gas burner adapted to be connected to a gas container containing liquefied gas and having pre-heating means (6) for heating liquefied gas, the means (11) for controlling the supply of fuel to the nozzle(s) of the burner are located in a conduit (7, 9) connecting the pre- heating means (6) with the nozzle(s) so as to ensure that the control of the supply of fuel is always effected on fuel in a gaseous state. <IMAGE>

Description

SPECIFICATION Gas burner This invention relates to a gas burner adapted to be connected to a container containing liquefied gas and comprising pre-heating means for evaporating liquefied gas and means for controlling the supply of fuel to the nozzle(s) of the burner.

The formation of roof coverings from roofing felt comprising a layer of heat activatable binder on a support is ordinarily effected by heating said binder to melting temperature simultaneously with the application of said felt to said support so as to firmly bond the felt to the support.

The heating of the binder is preferably effected with a gas, e.g. propane or butane gas, which is stored in pressurized containers in liquefied state.

When the prior art gas burners are used outdoors, the heat necessary to evaporate the liquefied gas is supplied from the surrounding atmosphere and the control of the supply of gas to the nozzle(s) of the burner is ordinarily effected with one or more valves located in the gas supply conduit connected to said nozzle(s).

When the outdoor work is carried out in cold weather, the prior art burners present severe problems which are due to the fact that the heat necessary to evaporate the liquefied gas cannot be supplied in normal manner. Consequently, a normal gas supply rate cannot be attained.

It has been attempted to eliminate these problems by utilizing a gas burner having a coiled pipe which is in direct contact with the flame and by passing the liquefied gas through said pipe before it is supplied to the nozzle(s) of the burner.

By using such a burner arrangement it is possible, even when using liquefied gas, to supply a sufficient amount of gaseous fuel to the nozzle(s) tb maintain a flame of a desired size. In practice, the supply of liquid fuel to the burner becomes relevant when it is necessary, e.g. in cold weather, to place the pressurized gas container upside down, i.e. with the valve of the container turning downwardly in order to empty the container.

In the prior art burners of the above-mentioned type the supply of the fuel to the gas burner is controlled by means of valves located in a pipe connecting the pressurized gas container with the coiled pipe. The control valves are for example located in the handle of the burner.

Control valves mounted in this manner do not function satisfactorily and special problems arise when the heat activatable binder is to be heated in spots and the fuel consequently has to be supplied in pulses.

Thus, the prior art valve arrangements do not allow the rate of supply of fuel to be satisfactorily controlled both when the fuel is gaseous and when it is liquid.

The object of the invention is to provide a gas burner which will operate satisfactorily both when the fuel supplied to the nozzle(s) is in gaseous and when it is in liquid state. According to the invention there is provided a gas burner which is characterized in that the control means are located in a conduit connecting the pre-heating means and the nozzle(s).

By locating the control means between the preheating means and the nozzle(s), the control of the fuel rate will always be effected on fuel in gaseous state and consequently the fuel rate may be exactly controlled. This is of particular importance when a roof covering material is to be bonded to a support in spots. In such cases the fuel can be supplied to the nozzle(s) in a pulsating flow with pulses of a well defined length.

The pulsating supply of fuel to the nozzle(s) can be effected manually but can also be effected automatically, for example with time-controlled valves.

The control means, for example one or more valves, are preferably located in the gas burner handle. Such a handle may comprise an internal passage in which a valve is inserted, one end of said passage being connected to the pre-heating means and the other end being connected to the nozzle(s) of the burner. The conduit connecting the pressurized gas container with the pre-heating means may be a pipe bypassing said handle or may comprise a further internal passage in said handle, said internal passage being constantly open.

The pre-heating means used in the gas burner according to the invention preferably consist of a coiled pipe mounted in the zone adjacent to the burner nozzle(s) and located concentrically therewith. In this manner the burner flame(s) will be in direct contact with the pre-heating means.

The gas burner according to the invention preferably comprises two valves located in the conduit connected to the burner nozzle(s). One of these valves, e.g. in the form of a needle valve, is located in the supply conduit and is constantly open during use in order to supply a sufficient amount of fuel to the nozzle(s) to maintain a flame in the intervals between the pulsating supplies of fuel. The other valve is mounted in a bypass channel which serves to generate the pulses in the flow of gaseous fuel to the nozzle(s).

The invention will now be described in further detail with reference to the drawings, in which: Fig. 1 shows a side view of the gas burner according to the invention, Fig. 2 shows the gas burner according to Fig. 1 in top view, and Fig. 3 schematically shows a longitudinal section through a handle of a burner according to the invention.

The gas burner illustrated in Figs. 1 and 2 comprises a socket 1 having a thread 2 for connecting the socket 1 to a source of liquefied gas, for example a pressurized gas container. The socket 1 comprises an internal angular channel 3 (see Fig. 3) which is connected to a fuel pipe 4 bypassing a handle which is designated 5 and being connected to a preheater 6 in the form of a coiled pipe which in turn is connected to a return pipe 7. The return pipe 7 is connected with the handle 5 and communicates with an internal channel 8 (see Fig. 3) in said handle. The internal channel 8 in the handle 5 is connected to a burner pipe 9 terminating in a nozzle (not shown) which is surrounded by a perforated cylinder 10 forming a mixing chamber for fuel and air.

As will appear from Fig. 3 a needle valve 11 is located in a restricted part of the internal channel 8 and when said needle valve 11 is screwed down, it stops the supply of gaseous fuel to the nozzle. During use the needle valve 11 is adjusted so as to produce a constant small flame when the valve discussed below is closed.

The handle 5 also comprises a bypass channel 12 and a ball valve 1 3 located therein. The ball valve 13 can be opened and closed by operation of a cock 14 in a manner such that gaseous fuel via the bypass channel 12, the ball valve 13 and a further channel 1 5 flows to the burner nozzle under full gas pressure. When the use of the burner is to be discontinued, the cock 14 is returned to its starting position thus closing the ball valve 1 3 whereby the supply of gas through the bypass channel 12 is stopped.

In the intervals in which no fuel is supplied to the burner through the bypass channel 12, only the above-mentioned small flame will burn.

When the work has to be started, the burner is ordinarily cold and it will therefore be necessary to use gaseous fuel. This is achieved by placing the pressurized gas container in its normal position, i.e. with the valve turning upwardly. Subsequently, when the pressurized gas container has been cooled, it may be necessary to turn the container upside down in order to supply the necessary amount of liquid fuel to the burner. However, by using the valve arrangement of the invention, the use of liquid fuel will present no problems and no adjustments have to be made because the valves located in the handle continuously operate on gaseous fuel.

The arrangement according to the invention also allows the control of the supply of fuel to the nozzle to be effected in any desired manner both in case where a manually operated valve is used in the case in which the valve is automatically controlled to produce flame pulses.

Claims (3)

1. A gas burner adapted to be connected to a container containing liquefied gas and comprising pre-heating means for evaporating liquefied gas and means for controlling the supply of fuel to the nozzie(s) of the burner, characterized in that the control means are located in a conduit connecting the pre-heating means with the nozzle(s) of the burner.

2. A burner according to Claim 1, characterized in that the pre-heating means are connected with an internal channel in a burner handle and that said internal channel comprises control valves.

3. A gas burner adapted to be connected to a container containing liquefied gas, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.