GB2269749A

GB2269749A - Non-clogging smoke generator

Info

Publication number: GB2269749A
Application number: GB9216519A
Authority: GB
Inventors: Ian David Roffey
Original assignee: LE MAITRE FIREWORKS Ltd
Current assignee: LE MAITRE FIREWORKS Ltd
Priority date: 1992-08-04
Filing date: 1992-08-04
Publication date: 1994-02-23
Anticipated expiration: 2012-08-04
Also published as: GB2269749B; GB9216519D0

Abstract

Smoke is produced by supplying first non-clogging liquid such as mono- or dipropyleneglycol under pressure to a heat exchanger (24) and thence to a mixer (28) to which a second liquid such as glycerol or glycerine is supplied, fluids of the liquids being mixed in the mixer and forced out of an outlet in the form of smoke. <IMAGE>

Description

IMPROVED SMOKE GENERATOR The present invention relates to a smoke generator.

Known smoke generators such as are shown in European Patent Specification Published under No. 0255232 A include a liquid supply of a suitable glycol based generating fluid such as polypropyleneglycol which is pumped through heat exchange coils in a heater where the mixture is heated to about 2600 to produce a mist. A thermostat is associated with the apparatus to control the heater temperature. In such a generator the fluid is heated to above its boiling point within the heater and is then ejected in the atmosphere to produce a fog or mist effect. The particular fluid used is required to be of a minimum toxicity and is also desired to be such that it will not clog up the exchanger coils by depositing decomposition products.

However, the resulting fog from such an apparatus has a limited persistence. The most desirable fluid to improve persistence would be glycerol or glycerine. However this fluid decomposes badly and tends to clog up fluid ducts in the apparatus and therefore apparatus designed to use this fluid requires a heater construction which can be stripped for cleaning or else a means for withdrawing the fluid after use. These provisions have not been very satisfactory. Therefore manufacturers of generators generally avoid the use of glycol or glycerine in such machines. This is the case in the aforesaid generator.

A smoke generator according to the invention comprises a means for supplying a first and non clogging liquid, a heat exchange to heat the first liquid, a mixer connected to an outlet of the heat exchanger, a means for supplying a second smoke generating liquid to the mixer and a pressurising means arranged to force a fluid of the first liquid through the heat exchanger and mixer to an outlet for fluids of both liquids mixed in the mixer.

Preferably the first liquid is mono- or di-propyleneglycol whilst the second liquid is glycerol or glycerine. The mixer is preferably a venturi type mixer with the supply of the second liquid feeding an auxilliary supply duct opening into a main duct through which a fluid of the first liquid is pumped. Typically a 4.8 mm (3/16 inch) diameter main duct about 25 mm long to provide with a 1.3 mm (0.05 inch) auxilliary supply duct having an outlet facing at an angle of about 45 to the axis of the main duct toward the outlet of the main duct. The pressurising means may be a pump or a pre-pressurised container of the first liquid.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatical perspective view of a smoke generator according to the invention, and Figure 2 is a diagram of a fluid mixer for the generator of Fig. 1.

In the drawings there is shown a pressurising means for supplying a first liquid comprising a pressurised canister 2. The canister is seated on an inlet coupling 4 from whence a duct 6 leads to a solenoid operated on/off valve 8 controlled by an on/off electrical switch 10. From the valve 8 a further duct 12 leads to a length of tubing 14 preferably flattened, which is "snaked" round grooves 16 in an aluminium block 18 in which is one or more heater elements 20 connected to a heater supply 22. The tubing 14, block 18 and heater element(s) form a heat exchanger 24.

Connected to the outlet 26 of tubing 14 of the heat exchange is a mixer 28 comprising a main duct 30 and an auxilliary supply duct 32 for supplying a second liquid.

The main duct has an internal diameter of about 4.8 mm.

The auxilliary supply duct has an internal diameter of about 1.3 mm and this outlets at an outlet 34 facing an output nozzle 36. The face of the outlet is about 450 to the axis 38 of the main duct so that the mixer acts as a venturi type device.

The auxilliary duct 32 is connected by means of a duct 40 to a supply of a second liquid being a bottle 42.

The first liquid is mono- or di-propyleneglycol whilst the second liquid is glycerol or glycerine.

To use the generator, the heater is turned on to heat the heat exchanger to a required temperature controlled by a temperature sensor 44. Valve 8 is then opened by switching on switch 10. The first liquid is pressurised, canister 2 is then forced through the- heat exchanger 24 to mixer 28 where a fluid of the second liquid is induced to mix with the fluid of the first liquid. The combined fluids then exit from outlet 36 in the form of a mist or fog.

Claims

CLAIMS:

1. A smoke generator comprising a means for supplying a first and non clogging liquid, a heat exchanger to heat the first liquid, a mixer connected to an outlet of the heat exchanger, a means for supplying a second smoke generating liquid to the mixer and a pressurising means arranged to force a fluid of the first liquid through the heat exchanger and mixer to an outlet for fluids of both liquids mixed in the mixer.

2. A method of making smoke comprising the steps of (a) supplying a first and non clogging liquid to a heat exchanger (b) heating the first liquid in the heat exchanger (c) forcing a fluid of the first liquid through the exchanger to a mixer (d) supplying a second smoke generating liquid to the mixer (e) mixing fluids of both liquids in the mixer (f) forcing the mixed fluids of both liquids from the mixer to a fluid outlet.

3. A smoke generator according to claim 1 wherein the means for supplying a first liquid comprises a first container arranged to be pressurised.

4. A smoke generator according to claim 3 wherein the pressurised first container contains mono- or dipropyleneglycol.

5. A smoke generator according to any one of claims 1, 3 or 4 wherein the means for supplying a second liquid comprises a second container.

6. A smoke generator according to claim 5 wherein the second container contains glycerol or glycerine.

7. A smoke generator according to any one of claims 1 or 3 to 6 wherein a valve is provided to control a duct of the means for supplying the first liquid, said duct being connected to an inlet of the heat exchanger.

8. A smoke generator or method of making smoke according to any one of claims 1 to 7 wherein the heat exchanger comprises a block in which is one or more heater elements and a length of tubing preferably flattened which is "snaked" around grooves in the block.

9. A smoke generator or method of making smoke according to any one of claims 1 to 8 wherein the mixer is a venturi type mixer having a main duct through which a fluid of the first liquid is arranged to be forced and an auxiliary duct opening into the main duct through which the second liquid is arranged to be supplied.

10. A smoke generator or method of making smokeiin which

the main duct is substantially 4.8 mm in internal diameter and the auxiliary duct is substantially 1.3 mm in internal diameter.

11. A method of making smoke as claimed in any one of claims 2 or 8 to 10 wherein the first liquid is a mono- or di-propyleneglycol.

12. A method of making smoke as claimed in any one of claims 2 or 8 to 11 wherein the second liquid is glycerol or glycerine.

13. -A smoke generator substantially as described with reference to the accompanying drawings.

14. A method of making smoke substantially as described with reference to the accompanying drawings.