GB2387330A

GB2387330A - Airborned bacteria exterminator

Info

Publication number: GB2387330A
Application number: GB0208381A
Authority: GB
Inventors: Jeffrey Martyn Sass
Original assignee: VACMATIC INTERNAT Ltd
Current assignee: VACMATIC INTERNAT Ltd
Priority date: 2002-04-11
Filing date: 2002-04-11
Publication date: 2003-10-15
Also published as: GB0208381D0

Abstract

An air steriliser comprises UV opaque conduit 3, with air intake 2, air outlet 5, fan 8 to draw air through the conduit and UV lamps 4 to irradiate and sterilise the air as it passes through. The conduit is optionally mounted in casing 1. The conduit has substantially no obstructions other than lamps 4, which may be oriented parallel to the air flow to maximise exposure of the air to the UV radiation. Additional lamps may be mounted normal to the air flow to provide a tortuous flow path. A plurality of the conduits may be arranged in a bundle parallel to a common axis, with their air intakes oriented in different directions, which ensures that air is drawn into the steriliser apparatus over 360 degrees. The steriliser conduits may be mounted within, or adapted to form part of, a larger air conditioning system.

Description

TITLE: "AIRBORNE BACTERIA EXTERl\IlNATOR MEANS" BACKGROUND

This invention relates to the extermination of airborne bacteria, virus and DNA by using; ultra violet rays. These rays are used and well known as a means of combating bacteria, virus and DNA. The ultra violet lamps in the normal way are fitted in a housing which also contains a fan to draw air into the housing. The air that is drawn into the housing passes over the ultra violet lamp, on its exit path to the air outlet. It is possible that some of the bacteria or spores escape through the air outlet without having spent any or sufficient time under the ultra violet rays, or perhaps are sheltered by foreign matter drawn in by the fan, or by finding a path through the housing that is sheltered from the ultra violet rays.

When it comes to larger areas that are to be eradicated a larger or stronger fan could be used but the point can be reached where either the noise from the fan or the draft from the increased air movement is not acceptable. A possible alternative that has been proposed is to have a number of ultra violet ray lamps placed on either the walls or ceiling of the area concerned. This can be satisfactory for the smaller rooms or areas but is not suitable for larger areas such as hospital wards, operating theatres or waiting rooms. In these larger areas the separate units drawing in air tend to conflict rather than co-operate due to the airflow patterns which they create, so that some volumes of the contaminated air pass unnecessarily repeatedly through the ultra violet system while others are relatively untouched. Alternatively a single pocket of air may be drawn in different directions at once towards different ultra violet ray units, never reaching one.

-2- THE INVENTION

This invention is designed to irradiate airborne bacteria, viruses and DNA. The advantages of the embodiments of this invention are that all air drawn into the system is forced to enter the tunnel or enclosure and can only exit once it has passed through the whole length of the ultra violet ray system. The features of Claims 1 - 7 - 16 - 17 ensure that this is the only path that

airborne bacteria/viruses can take once they have been drawn into the airstream.

The speed at which the air passes through the system, as applying to Claims 1 to 17, is calculated by using the following information: total length of ultra violet lamps; wattage of the lamps; wall area of tunnel or enclosure; allowance for friction of air movement created on walls of tunnel or enclosure. This calculation decides the size and specification of the fan or i

other means of air movement to be used.] The features of Claim 3 are such that the ultra violet lamps are so placed within the tunnel or enclosure that the contaminated air can only travel down their length and not across them, giving the rays a longer period to penetrate. When space is limited and a long length of ultra violet lamps is required, the features of Claim 15 provide for this eventuality.

Access to service and clean the ultra violet lamps and the walls of the tunnel is provided by i the features used in Claims I - 5 - 16 - 17.

The aspect of the invention for the larger areas is that there are provided airborne bacteria exterminator means reaching a circumference of 360 simply by putting a plurality of the invention into a single assembly. The features of Claims 6 to 14 provide for this coverage.

Using the invention for recirculated air is provided for in Claim 16. There are many circumstances where recirculated air has to be used. Basements of buildings, storage rooms and aircraft are but a few.

........ ...DTD: In many circumstances bunking is used for air conditioning and/or recirculation purposes.

The features of Claim 17 provide for the tunnel or enclosure to be fitted inside the bunking.

-3 PARTICULAR DESCRIPTION RELATING TO THE DRAWINGS

INDEX OF DRAWINGS

FIGURES 1- 4 - 5 & 6/are perspective views of the invention.

FIGURES 2 & Square sectional views of the airflow trail.

FIGURE yqis a view in perspective of the casing or housing containing the tunnel or enclosure ofthe invention.

FIGURE This a section of the tunnel or enclosure showing the airflow trail and direction.

FIGURE This a section of a multi-directional tunnel or enclosure.

FIGURE This a view in perspective showing six tunnels or enclosures in one cluster.

FIGURE 5/qDetails marked 2 - 3 - 5 - 9 Detail 2 Air inlet port grid Detail 3 Tunnel or enclosure Detail 5 Air outlet port Detail 9 Extension compartment to house electrical control gear The dimensions and shape of this tunnel or enclosure can vary.

This embodiment occupies a much smaller space than Figure 1.

-4 FIGURE 61q Details marked 2 - 3 - 5 Detail 2 Air inlet port grid Detail 3 Tunnel or enclosure Detail 5 Air outlet port The dimensions and shape of this tunnel or enclosure can vary.

This embodiment is the basic tunnel or enclosure. The electrical control gear is situated remotely and this unit occupies the minimum amount of space.

FIGURE 71q Details marked 10- 11 Detail 10 Recirculated air distribution duct Detail 11 Air conditioned air outlets FIGURE $1q Details marked 3 12 - 13 - 14 - 15 Detail 3 Tunnel or enclosure containing ultra violet lamps Detail 12 Overhead air vents Detail 13 Air conditioned and filtered air supply feed Detail 14 Overhead recirculated air supply Detail 15 Adaptor to reduce size and shape of tunnel or enclosure open end to fit the re circulated air duct FIGURE 919 Details marked 16 -17- 18 Detail 16 A section of bunking showing hinged door open Detail 17 Perspective view of special translucent tunnel or enclosure complete with 5 ultra violet lamps Detail 18 Hinged door for maintenance

DETAIL OF DRAWINGS

FIGURE 1 Detail numbered 1 - 2 - 3 - 4 - 5 -

Substantiate and support Claim 1.

Detail Numbered 1 is the casing or housing containing the invention. This casing or housing can vary in shape and size according to requirements and it is fitted with a safety switch going into the off position when opened.

Detail Numbered 2 is the air inlet port grid to let the contaminated air into the tunnel or enclosure. Detail Numbered 3, which also supports Claim 3, is the tunnel or enclosure which is made of a material that will not let the ultra violet rays through its wall thickness and is manufactured in such a way that a section is easily removed to give easy access to the ultra violet lamps.

This removable section is also fitted with a safety switching device when an outer casing or housing is not used. The shape and dimensions may be varied according to requirements and a section or all of the tunnel or enclosure may be transparent.

Detail Numbered 4 are the two ultra violet lamps used for this example. The number of tubes and their dimensions and wattage can be increased or decreased according to requirements. Detail Numbered 5 is the air outlet port.

Detail Numbered 8 is the fan or other means to suck the contaminated air into the tunnel or enclosure. This fan or other means may be mounted horizontally as shown or it can be mounted vertically.

-6 FlGURE 2h Detail numbered 3 - 4 - 6 This shows a section of the embodiment tunnel or enclosure and supports the statement made

in Claim 2.

Detail Numbered 3 is a section of the tunnel or enclosure.

Detail Numbered 4 shows two ultra violet lamps.

Detail Numbered 6 indicates the constant direction of the airflow.

FIGURE 3h Detail numbered 2 - 3 - 4 - 5 - 6 Detail Numbered 2 Air inlet port grid Detail Numbered 3 Tunnel or enclosure Detail Numbered 4 Two ultra violet lamps Detail Numbered 5 Air outlet port Detail Numbered 6 Direction of airflow The benefit of this part of the invention is that, in a comparatively short space, long lengths of ultra violet lamps can be built up. In addition to this on each turning point of the assembly the bacteria are attacked from all sides and also subjected to the ultra violet rays for a longer period. There is also a cost benefit that a number of ultra violet lamps can be used from only one fan.

T

-7 FIGURE 4h Details marked 2 - 5 - 7 Detail Numbered 2 Air inlet port grid x 6 Detail Numbered 5 Air outlet port x 6 Detail Numbered 7 Outer housing x 1 Figure Prefers to Claim 4.

This embodiment gives a plurality of six airborne bacteria exterminators covering 360 . This unit has an outer casing that is made to hold six tunnel or enclosure units complete with all aspects of the invention. This gives a spread of directions arranged substantially in a plane and spread around 360 degrees. This embodiment is suitable for pedestal (or column) mounting or for suspension from, or flush fitting to, a ceiling. Access to all internal parts is either by removing the top or bottom panel. Providing the air drawn in covers an area of 360 the plurality of the invention may be less or more than the quantity shown in Figure 4.

FIGURE s|qS a view in perspective of a tunnel or enclosure with a side extension to take control gear.

FIGURE 6|s a view in perspective of a tunnel or enclosure without a side extension.

FIGURE 7lqs a sectional view of an aircraft cabin showing the recirculated air distribution duct and conditioned air outlets.

FIGURE 81 a view of the recirculated air pipework and the tunnel or enclosure in place.

FIGURE 9|s a perspective view of a section of bunking showing two of the tunnels or enclosures with 5 ultra violet lamps in each. It also shows the hinged door.

-8 TEST RESULTS

FOREWORD

The tests that follow were carried out on a pre-production instrument. The test results, which are recognised as being extremely good, follow on the next twelve pages. The inefficiencies of the test instrument were noted and described on Sheet I headed "Background". Although

at the time of presenting this Patent Application revised test results have not yet been received we have every expectation that, because this invention overcomes all the deficiencies of the air steriliser used and because we are using the identical powered fan and identical ultra violet lamps of the same wattage, the updated test results of our production instruments will be greatly improved.

l The Freeman Hospice Repaql TEST LABORATORY

_ I Contact Name: Kay Chivers Contact Address: Microbiology Department Freeman Hospital Freeman Road Newcastle upon Tyne NE7 7DN

Telephone: 0191 284 3111 Ext 26286 Fax: 0191 223 1226 E- mail: Homeresearch(compuserve.com Test Product: Bacticlean Organism tested: Methicillin resistant Staphylococcus aureus TEST CIlAMBER Dimensions: 70 cm x 70 cm x 130cm Volume: Approximately. 600 litres EXPERIMENTAL CONDITIONS

Date of test: 31/10/00 - 01/11/00 Exposure time: 10 min Sampling times: 1, 5, 10 min _ A Test temperature: 20Uc +t- IUC Report date: 01/11/00

Test Chamber Eoo\<iY E\JAcU HT10 Id OF BctlcLr:ntl I, /_v RuS I R r-t Q, nEn ton o ME1\C - IN ST9P4VOCQ A test chamber was constructed with internal dimensions of 70 x 70 x 1 30cm.

The volume of the chamber was approximately 600 litres. The chamber did not allow access of air except through a hepa-filter. The chamber also accommodated a small 1 cm port for inoculation of a bacteria aerosol. This remains sealed whenever possible. The chamber was also linked to a Caselle air sampler via an airtight connection. The Bacticlean/Anti-Virus instrument under test was sealed inside the test chamber. Before beginning any experiments, consecutive air samples were taken from the chamber until 'zero' colony counts were achieved indicating that the air inside the chamber was effectively free of viable bacteria. The Caselle sampler worked by sucking air from the chamber at a rate of 700 litres per minute. The air sample was introduced to the surface of a culture plate, which was composed of Columbia agar supplemented with 5% horse blood. Every air sample taken during the evaluation was of a two-minute duration. The fan on the Bacticlean/Anti-Virus instrument was allowed to run during all air sampling.

O'er C^EVALURTi0MVSlH 6fiCL4 RUTI/IRDS Swlci oFF A strain of methicillinresistant Staphyrcoccus aureus (MRSA) was obtained. -,.

from the National Extemal Quality Assurance Laboratory, Central Public i. A. Health Laboratory, Colindale, London. This strain was prepared in nutrient broth at a density equivalent to 3 x 108 bacteria per ml. A 10 ml sample of this suspension was aerosolised and introduced into the chamber. The fan on the Bacticlean/Anti-Virus was allowed to run for five minutes to circulate the air inside the chamber. The W was switched off at all times during this initial experiment. After the initial five- minute period, an air sample was taken and the culture was labelled 'time zero'. Once this sample had been taken, the Bacticlean/Anti-Virus was left to run for a further one-minute and a second sample was taken. This culture was labelled 'one minute'. The Bacticlean/Anti Virus fan was left to run for a further four minutes and a third sample was taken and labelled 'five minutes'. Finally, the Bacticlean/Anti-Virus fan was left to run for a further five minutes and a fourth sample was taken and labelled ten minutes'. All culture plates were incubated at 37 C for 48 hours and colony counts were performed. Colonies were confirmed as MRSA using standard methods.

After this experiment was completed the Bacticlean/Anti-Virus was left to run for an hour with UV switched on to effectively 'sterilise' the cabinet. In order to confimn that background counts had returned to zero, air samples were taken.

The whole experiment was then repeated in identical fashion to obtain duplicate results to ensure reproducibility.

Method II - Test Evaluation using Bacticlean/Anti-Virus instrument with UV switched on.

The whole of the above experiment was repeated in a duplicate and identical fashion except that the UV of the Bacticlean/Anti-Virus instrument was switched on between air samples. The control and test procedures can be summarised as follows:

Summary

Method I (UV off) - Bacticlean fan running during entire procedure. W switched off during entire procedure.

Introduce aerosol.

Leave air circulating for five minutes, Obtain 'zero' count Leave air circulating for further one minute. I Obtain '1 minute' count Leave air circulating for further four minutes.

Obtain '5 minute' count.

Leave air circulating for further five minutes.

Obtain '10 minute' count.

Sterilise' cabinet.

Repeat procedure.

Method II (UV on) - Bacticlean fan running during entire procedure. W switched off during air sampling.

Introduce aerosol.

Leave air circulating for five minutes Obtain 'zero' count.

Leave air circulating for further one minute with W on.

Swikh W off and obtain '1 minute' count.

Leave air circulating for further four minutes with W on.

Switch W off and obtain '5 minute'- count.

Leave air circulating for further five minutes with UV on. t Swikh W off and obtain '10 minute' count.

Sterilise' cabinet.

Repeat procedure.

A comparison of duplicate resulb therefore allowed for an assessment of the impact of IJV light as provided by the Bacticlean instrument on the reduction; of viable MRSA.

Run 1 1 3 a:: Raw data (chu/chamber) LOGIo Raw data v Methicillin resistant Methicillin resistant...

staDhYIocoocus aureus staphyloco cus aureus.

Time (mine) W on W off Time (mine) W on UV off 0 48000 52000 0 4.68 4.72 ..

3760 16000 1 3.58 4.20

740 4640 5 2.87 3.67..

10 1860 10 1.00 3.27.

Run 2 LOG'o Raw data Raw data (ctu/chamber) _ Methicillin resistant Methicillin resistant staphylococcus aureus staphylococcus aureus Time (mine) UV on W off Time (mine) W on UV off 67200 16800 0 4.83 4.23 _

24000 7600 4.38 3.88

2680 1050 5 3.43 3.02 _

10 90 1040 10 1.95 3.02

Summary - Average data showing LOGE reduction values over time

| Time W on W off 0.78 0.43

5 1.61 1.13

10 3.28 1.33

Results clearly show the reproducible effects of W exposure on S.aureus counts after an exposure time of 10 minutes. A Logic reduction>3 was activated, this Logic reduction was reduced to 1.33 when W was switched off.

Figure 1: Reduction of methicillin resistant Staphylococcus aureus colony forming units (CFU) per test.

chamber over 10 minutes using 'Bacticlean' (run 1). \v. \.

). I,'''\,'",\.',\

_. "I ''.'""

I,,\-.,,. 2

50000 j \L '''':'"''' l. ' \\,.',..

Bean \\ ' 200017- \\

01 2 3 4 5 6 7 8 ' 9 to lb.hld_' _Won -We off.

- Figure 2: LOG' (CFU/test chamber) reduction of methicillin resistant Staphylococcus aureus over 10 minutes (run I) .oo = 400 of ' 1 - _, _.

aim 125D- aft - --

1.oo-. -

B5D 01........ __

0 1 ' 2 3 4 5 e 7 69 10 T - pith_ _Wen unwon

Figure 3: Reduction of meicillin resistant Staphylococcus aureus colony forming units (Cam per test...

chamber over 10 minutes (run 2) i,,''''',''.''' Arm _,-'. '"'','',''''"'; 7 '',;','-.N,,,'.,,"

,'',\.''',",,\.".',"

Im \ '.,,,\, 4xxo. 7' \ ' I it'.

mono a\ 100 i W _ o 1 Z 3 4. 6 8 7 0 _UVon UVo Figure 4: LOGE (CFU/test chamber) reduction of methicillin resistant Staphylococcus Bureau over 10 minutes (run 2) Ural 1- 200 _,.

ADO T.

4 O ' 2 4 S 7 9 10

1-- Owen swear

BACTICLEAN DATA

ACTICLEIAN SURGERY TRIAL SURGLRY TRIAL TRIAL

DAY BACKGROUND TRIAL DATA..

YeASTS MOUL" HOSTS MOULDS MON 700 1Ct. 80 \ TUES 900 780 60 40..

WLD 16 9 40

THURS 1400

FR! 60C 50

MON 900 22C 90 A

TUeS 1300 3IlC - 40.

WeD 11 430120 50 THURS 2400

7000 60C50.

BACTICLEAN SURGERY TRIAL (95 CUBIC ME TR85)

BACTERIA YEASTS MOULDS

MON 3900 700300 BACKGROUND.

TUeS 4100 900780 weo 6200 1600900 RECURS 4900 1400450

8400 700 600

MON 7800 900 220

TU E!S 3900 1300 330

WED 4700 1100 430

TH U RS 8400 2400 700

FR1 2800 7000 600

MON 240 100 80 TRIAL

1-ues 190 60 40 WED 20 80 40

THURS 80 90 40

FRI 70 90 50

MON 90 40 90

TUeS 70 110 40 W ED 40 120 50

TH U RS 70 40

FRI 60 240 30

Pdge 1

c ' '1 c got 15: - SUnH Hi - F cD: _ I O O o _ _ _ _ _ _ _ _ _ SUnH1 a _ _ _ am 2 cat 3 0 0 A: _ - san O O 0 _ _ _ _ ___ _ - NOW

4, (1) fr o o o _ _ _ _ _ __ _ 183 {[(l) I 0 0-c _ _ _ _- sHnH 5; 2c O O oo ____ - _ a3M 4,.u, 0 0 c l _ __ sen , _ O O3 O - L _ __ NOW

V). 6 8 8

[_ CO 6 Cc tW/ SWSINV90

aciiclean 10 CU. METRE TRIAL TIME MINS SALMONELLA ASPERGILLUS CANDIDA LISTERIA PSEUDOMONAS

0 9300001 700000 14000002900000 1800000

490000310000 590000210000 210000

2 7800086000 5800060000 31000

5600051000 6800068000 52000

310030000 880078000 7700

41029000 90031000 4900

5206400 33019000 1200

_ 306200 508200 200

8 O4900 O1700 30

330 02100

10 07 070 7

Bacticlean 10 CU. METRE TRULL 3000000 -_ -- 1 AASpER N'ErLLLUAS | 2500000, -. _ _ _ _ LCIASNTEDRDIAA

:2000000- in/ - 1 '_.. _ PSEUDOMONAS . L_ _

15;00000- _. - l oooooo- 1. _! i" i" c" 31; PSEUDOMONAS

500000- 1' At LISTERIA my_ CANDIDA 0- / ASPERGILLUS

0 1 2 3 -SALMONELLA

8 9 10

- 1 1 1 1 1 1

- Bristol Water CQY l,est gesults Test Conditions (3 The W system was initial set up within a sample reception arm in which there is a regular movement of personal. After 1 week da: system was moved to a 11 Bogy laboratory which Here was little disturbance of air and in which only 2 analysts worded.

The system was led switched on and oaltemativei Or 24 bouts at a tone.

There were occasional variations to this arrangement.

Two open, Reshly-poured 90mm Yeast Extract Agar envronnnt plates were placed daily, one within 30cm ofthe base ofthe system (A) and the other about I metre Am the system (B), for 15 minutes.

These environment plates were then incubated fi'r 72 hours at 22 C after which tom all colonies growing on the plates were counted.

RESULTS - Sample Reception Area Day No UV SYSTEM Plate A Plate B 2 on counts / plate counts plate _ ' Sample Reception Area Test Resul" 8- _ Plate A counts / plate | 7 - | U Pbte B counts / pl J 0- off on off on off on 1 2 3 4 5 6

Day No and W By_ Off

RESULTS - Biology Laboratory 2 o Day No UV SYSTEM Plate A Plate B Off / On counts / plate counts / plate on 1 0 3 off 3 3 4 on 0 0 Biology Laboratory T - t R - ulte 3- / _ _

_ Pate A counts / labia e 1 11 1 off ' on ' d! ' 2 3 4 Day No and TV System On/Off

Claims

-21 CLAI1\iS 1. Ultra violet ray means characterized that it comprises a

tunnel or enclosure that has an air inlet port and an air exit port Air is drawn in by a fan or other device within the tunnel or enclosure, passes through the rays emitted from an ultra violet lamp or lamps killing, bacteria in particular but also any virus that is air born and destroying DNA The cleaned air then passes through the exit port of the tunnel or enclosure back into the environment This tunnel or enclosure may or may not have an outer casing and may be of any shape, e.g. rectangular, rounds oval or any combination of these shapes When the tunnel or enclosure is opened a switch or circuit breaker is automatically activated.
2. Means as claimed in Claim 1 characterised in that the speed at which the air passes through the tunnel or enclosure is calculated in relation to the length of the instrument and the length of the ultra violet lamps This calculated timing provides the ultra violet rays with sufficient time to become effective and complete their destruction.
3. Means as claimed in Claim 2 characterised in that because of the way the ultra violet lamps are fitted as shown in Figure 2 and because of the close proximity of the walls of the enclosure or tunnel the contaminated air travels down the whole length of the ultra violet lamp and not across it.
4. Means as claimed in Claim 3 characterised in that when additional ultra violet lamps are required and/or to jostle the bacteria or virus on its journey through the system any number of ultra violet lamps can be added These additions can be horizontal, vertical, curved or a combination of any of these An example is shown in Figure 3 The jostling effect ensures that the bacteria or virus is attacked from all sides on its way through the system.

-22
5. Means as claimed in Claim 4 characterised in that the material from which the tunnel or enclosure is manufactured does not let any ultra violet rays through its walls This is to prevent humans or animals being harmed by the ultra violet rays The walls of the tunnel or enclosure are Remountable for purposes of cleaning the lamps or changing them When l the tunnel or enclosure is demounted a switch or circuit breaker is automatically activated.
6. Means as claimed in Claim 5 characterized in that there is provided a plurality in one assembly drawing air into the instrument over 360 degrees This is ideal for the larger areas such as hospital wards' operating theatres and waiting rooms This is a useful multi-

directional instrument See Figure 4 This instrument consists of six tunnels or enclosures mounted as one occupying minimal space It reaches out from one central point.
7. Means as claimed in Claim 6 characterized in that each tunnel or enclosure has an inlet port pointing in respectively different directions.
8. Means as claimed in Claim 7 characterized in that each direction is substantially radial from a notional common centre.
9. Means as claimed in Claim 8 characterized in that said directions comprise a spread of directions arranged substantially in a plane and spread around 360 degrees.
10. Means as claimed in Claim 9 characterized in that said plurality is two.
11. Means as claimed in Claim 10 in that said plurality is three.
12. Means as claimed in Claim 11 in that said plurality is four. t
13. Means as claimed in Claim 12 except that said plurality is five.
14. Means as claimed in any one of Claims 6 to 13 characterized in that plurality of the tunnels or enclosures have at least one common outlet.

-23
15. Means as claimed in Claim 5 characterized where space is limited the tunnel or enclosure can be reduced to minimal dimensions Instead of a casing around the tunnel or enclosure as shown on Figure 1 an extension can be added to one or both sides of the tunnel or enclosure to house the control gear as shown in Figure 5 or the control gear can be wired and remote from the tunnel or enclosure as the example on Figure 6 shows the tunnel or enclosure only The control gear referred to may consist of a starter - choke - switch -

connectors - fuse - and wiring There may be additions or exclusions to these items.
16. Means as claimed in Claim 5 - Figures 7 & 8 refer This drawing shows a tunnel or enclosure modified to be fitted to recirculated air conditioned environmental control units as used in aircraft cockpits and cabins The tunnel or enclosure has an adaptor at each end that is fitted within the overhead air vent supply tube circuit Only the ultra violet lamps are fitted in this instrument The control gear is fitted either to the outer side of the tunnel or enclosure or remotely at some convenient point in the aircraft This instrument is also fitted with a switch or circuit breaker which is activated when the instrument is opened for service.
17. Means as claimed in Claim 16 - Figure 8 refers This claim is to fit the tunnel or enclosure system of ultra violet lamps to the inside walls of ducting using a hinged panel for access This shows a section of a typical air duct where a portion of one side of the ducting is cut away and a hinged panel of the appropriate size replaces the cut out portion to which are mounted the ultra violet lamps The hinged panel overlaps the section that has been cut out and is made to seal the opening so that no ultra violet rays can be seen with the naked eye When the hinged panel is opened for maintenance a switch or circuit breaker is activated and switches the ultra violet lamps off The control gear is fitted to the hinged panel The hinged panel is used for ease of maintenance.