GB2255819A

GB2255819A - Explosion proof light source for use in hazardous atmospheres

Info

Publication number: GB2255819A
Application number: GB9101902A
Authority: GB
Inventors: Charles Bernard Benson; Alan John Copeland
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-01-29
Filing date: 1991-01-29
Publication date: 1992-11-18
Anticipated expiration: 2011-01-29
Also published as: EP0598724A1; GB2255819B; WO1992013433A1; AU1175792A; GB9101902D0

Abstract

This is a portable, flameproof light source for use in hazardous (explosive) atmospheres. It requires only electrical input and has an integral cooling system. The unit comprises a case (10) with lid (ii), designed with the internal air circulation to provide cooling for the bulb and electronics, such that it will contain an internal explosion and will operate without the external surfaces reaching dangerous temperatures.

Description

LIGHT SOURCE FOR USE IN HAZARDOUS ATMOSPHERES This invention relates to a sealed, internallo '1 o r c e d a I r convection cooled. fiam2proof light source for use in hazardous atmospheres.

Light sources are well known and widely used in many types of endoscopic and other inspections. The maiority of these units force air from the surrounding atmosphere over the limD envelope for cooling, and are therefore considered undesireable for use in hazardous atmospheres. Those units which are classified for use in hazardous areas use one or more of the following methods of cooling: exotic gases, a high pressure compressed air supply or a mass of material to both absorb and dissipate the lamp's heart.

The light source described herein could if required use 8 gas other than forced air cooling.

Because the lamp generates a considerable amount of heat, it requires a large amount of cooling when used in hazardous areas; the current designs of light sources are either expensive to maintain or difficult to use or have a relatively short duty cycle befora overheating and being thermally tripped.

According to this present invention this internally forced air convection cooled light source is a sealed box like structure which has cooling fins on both sides of the four normally vertical primary walls. Air contained within the sealed compartment of the light source is circulated by a fan over the lamp and optical system to cool them. This air is also circulated through internally finned ducts.

The fins in these ducts absorb heat from the forced air. Heat from the internal fins is transsitted by conduction to the external fins which in turn give up their heat to the ambient atmosphere. Light from the lamp is passed through a sealed optical window in one wall to a multi function fully vairable mounting for a fibre optic light guide or another light transmitting medium.

The specific embodiment of the invention will now be described by example, with reference to the accompanying drawing in which: Figure 1 shows the external configuration of the light source.

Figure 2 shows the principle of the internal forced air cooling system.

Referring to Figure 1 the forced air convection cooled light source comprises of a case 10 with a lid, 11 which when fitted prevents the interchange of gases, between case internal cavity and ambient atmosphere. The external vertical finned primary wall a. 12 are protected by rod frame 13 which protrudes front and back to form carrying handles for the ooerator. At the front of the light source is a Multi Function Fully Variable Mount 14 which has an orifice 15 for optical light guides. Electrical oower for the light source is provided by and through a sealed cable 16.

Figure 2 shows the internal configuration of the light source with the lid 11 removed. The light from the lamp 17 is focussed through the optical system iB onto the optical window 10, which is positioned behind the Multi Function Fully Variable Mount 14. The fan; unit 20 is positioned behind the lamp 17 and in front of the electronic power supply system 21. The primary walls 12 are all finned vertically on the outside and horizontally on the inside. The inside horizontal fins of the primary walls form part of a duct system 22. Partitions 23 form the inner most wall of these ducts. The oart it ions 23 are left open on two of the walls to provide an inlet and outlet for air from the fan 20. The air which is contained within the sealed enclosure is circulated by the fan 2C over the lamp 17 and optical system 18. After passing over the lamp 17 and optical system 18 the, now heated, air enters the inlet orifice of the finned ducts 22.

Whilsi passing through these finned ducts the air gives up a proportion of its heat. The now cooler air exits the ducts Into the electronics compartment 21, in which is situated the inlet of the fan 20.

Claims

CLAiMS

1. A sealed, internally forced air convection cooled light source which comprises of z lamp and optical system which are cooled by air, forced over them by a fan; the heated air gives up its own heat to the fins contained within the internal ducts.

2. A sealed, internally forced air convection cooled light source which use a Z circulating gas other t h an a I r

3. A sealed, internally forced air convection cooled light source which employs a single or multiplicity of tubular ducts to cool the internally circulated air or gas.

4. A sealed, internally forced air convection cooled light source with a lamp or optical system specifically designed for use with fibre or liquid optic equipment.