GB2180761A - Respirator apparatus - Google Patents

Abstract

Respirator apparatus for use in association with an air operated device such as a spraygun or for use alone employs: a source of air in high volume and at low super-atmosphere pressures comprising a housing (14) having a turbine air compressor (40), a primary plenum discharge chamber (26), Fig. 1, (not shown) with at least one outlet (52) and a secondary plenum discharge chamber (24) which communicates with the primary plenum discharge chamber via flow restrictor means (28) and has an outlet (58). A filter (60, 62) filters the flow of secondary air. A flexible air delivery tube (54, 74) is positioned in communication with a discharge side (66) of the filter (60, 62) for receiving and conveying filtered air therefrom. A helmet, mask or visor (88) is positioned in communication with an end of the flexible air delivery tube (54, 74) remote from the filter for receiving filtered air therefrom and has a face seal (90) to prevent ingress of the surrounding air. The apparatus can deliver at least 150 litres/minute of air to the visor (88) to maintain its window (89) clear of condensation and to meet the requirements of the user, and the air reaching the visor (88) is cool enough to permit extended periods of wear. <IMAGE>

Description

SPECIFICATION Respirator apparatus FIELD OF THE INVENTION This invention relates to respirator apparatus particularly intended for use in association with a paint spraygun, although it may also be used alone or in association with other airoperated devices such as drilling or sanding apparatus.

BACKGROUND TO THE INVENTION Paint sprayguns have traditionally been operated using compressed air at relatively high pressure in an airline fed from an air compressor or reservoir tank and it is known, e.g.

from Canadian patent specification No.

466452 and French patent specification Nos 853389 and 1037477, to provide a T-connector in a delivery hose to the spraygun and to use one branch of the connector to feed breathing air to a mask or visor. A typical system available in the UK is the so-called Clearways air-fed visor system in which a branch airline feeds a visor having therein a visor tube formed with slits for discharge of air into the space between the visor and the user's face.

More recently sprayguns have come into use that use as air source a turbine unit that produces a high volume of compressed air at a relatively low positive pressure, typically 2 to 3 psi (14 to 21 KPa). Such units employ a combined electric motor and turbine unit driven by mains electricity or occasionally by a small internal combustion engine and are available in the UK from Sprayfine Limited of Bournemouth, Dorset under the trade names Mistral, Cyclone, Sirocco, Hurricane and Tornado.

Such turbine units have not hitherto been used in association with a helmet or visor and it was open to doubt whether such a turbine unit could act as air source both for the spraygun and for a helmet or visor. It has been found that unless the volume of air fed to the helmet or visor is maintained at least 120 and preferably at least 150 litres/minute or above the window will mist over and continuous wear is impossible. Doubt existed whether such a visor system was suitable for use in association with a turbine unit in view of the low working pressure. Furthermore, the air fed to the spraygun line is at about 1 5"C above the ambient temperature partly due to compression but mainly due to the elevated working temperature of the turbine and motor.An air fed at that temperature would give rise to severe user discomfort and prevent continuous wear of the helmet or visor for extended periods.

SUMMARY OF THE INVENTION It is an object of the invention to provide respirator apparatus that employs high volume low pressure air direct from a turbine as the source of breathing air and that provides a flow of air to a visor or mask that is adequate to meet the requirements of the user whilst preventing misting up of a window of the visor or helmet and whilst delivering air over an intended supply pipe of length 15 to 25ft (4 to 8 metres) at a sufficiently low temperature to be acceptable to the user.

The invention provides respirator apparatus comprising: a source of air in high volume and at low super-atmospheric pressures comprising a housing having an air inlet, a turbine air compressor in the housing in communication with the inlet, a primary plenum chamber in the housing in communication with the discharge side of the air compressor for receiving the flow of compressed air therefrom, at least one outlet leading from the primary plenum chamber for discharge of a primary flow of air, a secondary plenum chamber in communication with the primary plenum chamber via flow restrictor means for receiving a secondary air flow from the primary plenum chamber, and an outlet leading from the secondary plenum chamber; a filter positioned in communication with the outlet from the secondary plenum chamber for filtering the flow of secondary air;; a flexible air delivery tube positioned in communication with a discharge side of the filter for receiving and conveying filtered air therefrom; and a helmet, mask or visor positioned in communication with an end of the flexible air delivery tube remote from the filter for receiving filtered air therefrom and having a face seal to prevent ingress of the surrounding air.

BRIEF DESCRIPTION OF THE DRA WINGS An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a turbine air compressor unit forming a source of compressed air for use in respirator apparatus according to the invention; Figure 2 is a schematic drawing of combined paint spray and respirator apparatus according to the invention; Figure 3 is a section of the downstream end of a visor tube forming part of the system of Figure 2; and Figure 4 is a section on the line A-A of Figure 3.

A principal object of the invention is to provide a system which gives effective respiratory protection to the user of a turbine-fed spraygun, achieves a high degree of wearer acceptability and is cost-effective. To provide adequate respiratory protection requires the visor to be supplied with a sufficient flow of contaminant-free air. The volume of air sup plied should be in excess of that required by a user under all breathing conditions, thus ensuring a permanent internal positive pressure.

Peak inspiration rates during periods of vigorous physical work are not normally greater than 120 litres/min (British Standard BS 4558, 4667 and 4771). To ensure a minimum supply of 120 litres/min, a flow rate not less than 150 litres/min was chosen as the target rate.

It is also desirable that the air supplied to the visor is free from hazardous substances and pollutants. Without any form of sub-micron filtration on the turbine unit it would be necessary to ensure that the air intake to the turbine was always placed in a "clean" environment. Even then, naturally occurring odours and dust, together with any fumes created within the turbine itself, could cause discomfort to the wearer. Thus it is desirable to incorporate a filtration system to remove nontoxic odours and respirable dusts (particle size 0.3-5.0 microns). If the turbine unit was placed in the paint environment then the filtration system would need to be of substantial proportions and require frequent changing.

Such a system would not be practicable and the invention is intended to operate outside the immediate working environment in a "clean" atmosphere with a low capacity backup filter in the air line connecting the turbine to the visor. The system should desirably operate with air and paint supply lines 15 to 25 feet (4 to 8 metres) long.

In Figure 1 an electrically driven turbine compressor (Sprayfine Cyclone) comprises a generally rectangular housing comprising a lid, base and sidewalls 10, 12, 14, front and rear end wails 16, 18 and a partition 20 dividing the housing into a chamber 22 defined between wall 16 and partition 20 and primary and secondary discharge chambers 26, 24 defined between partition 20 and wall 18 and separated by baffle 28. Openings 30, 32, 34 are respectively formed in the wall 16, the partition 20 and the wall 18 and those in the walls 16, 18 are closed off by inlet filters 36, 38.A motor and turbine assembly 40 is received in the opening 32 on sealing ring 33 with its motor 42 in the chamber 22 communicating with the opening 30 to which it is sealed by annular air separator 44 and with its turbine 46 in plenum chamber 26. Accordingly when motor 42 is running air is drawn through filter 36 and opening 30 into the motor 42 which it cools and air is also drawn through filter 38 and opening 34 into an opening 47 in an end wall 49 of turbine 46 with a sealing ring 48 positioned around open ing 34 in compression between walls 18 and 49. The turbine 46 is a two stage radial flow turbine and air discharged from its ports 50 maintains a positive pressure of 2 to 3 psi (14 to 21 KPa) in the plenum chamber 26.A first discharge port 52 in the wall 18 leads from the chamber 26 to an air hose 53 connected to a spraygun 56 of a kind adapted for operation with the high volume low pressure air flow which passes along hose 53 both when the gun is operative and when it is inoperative. A restricted flow of air passes baffle 28 and enters secondary plenum chamber 24 from which it discharges, again at 2 to 3 psi (14 to 21 KPa) positive pressure, via a second discharge port 58 in the wall 18.

The second port 58 is provided with a threaded spigot 59 and bleeds a proportion of the air from the internal turbine 40 at a pressure of typically abut 2.85 psi (20 KPa) with the spray gun 56 on and 3.05 psi (21 KPa) with the spraygun 56 off. A cartridge chamber 60 is screwed directly onto the spigot 59 and houses a replaceable cartridge 62 having both a particle filtration and vapour adsorption capability provided by a coalescing filter and body of activated carbon. Access to the cartridge 62 is by a bayonet fitting between parts of the chamber 60. The cartridge 62 should desirably pass about 250 litres/min of air at the indicated supply pressure. A pressure gauge 64 may be witted to the chamber 60 downstream of the cartridge 62 enabling the downstream pressure to be monitored and indicating when the cartridge 62 needs replacing.As the coalescing dust filter element of the cartridge 62 becomes progressively clogged, the downstream pressure and hence flow rate reduces and a pressure threshold can be marked on gauge 64 indicating the need for a cartridge change. Alternatively the cartridge can simply be inspected visually from time to time, a colour change indicating the need for replacement.

The downstream end of the chamber 60 is provided with a threaded outlet spigot 66 to which the supply hose 54 which is of length 15 to 25 feet (4 to 8 metres) overall and internal diameter 1/2 inch (12 mm) is con nected by means of a female swivel connector 68 and ferrule. The downstream end of the hose 54 is connected by female finger swivel 70 to a fir-tree connector 72 of a pigtail hose 74, the connection between the main hose 54 and the pigtail hose 74-thereby being readily detachable manually. The downstream end of pigtail hose 74 is connected by male fir-tree connector 76 to a transfer block 78 that steps from the 12 mm diameter main supply to the 8 mm internal diameter of a visor tube 80 whose upstream fir-tree end connector 82 is attached to the other side of block 78. The block 78 is carried by means of a nylon or other plastics saddle 84 on a waist belt 86 and is free to slide along the belt 86 to facili tate wearer adjustment.

The visor tube 80 feeds air to a mask or visor 88 having a window 89 and a surround 90 of soft plastics foam that seals around the face to prevent ingress of the surrounding air.

It has a downstream diffuser end located within the visor 88 (Figures 3, 4) which needs to diffuse the air flow over the inside face of the visor 88 without inducing any direct air stress that could lead to wearer discomfort and at the same time not increase the flow resistance of the visor feed tube 80 resulting in a drop in flow rate. To ensure that these requirements are met the foraminous downstream end of the visor tube 80 is closed by means of a plug 92 and pierced with a large number of holes 94 which are equi-spaced around the periphery of the tube 80 and along the length of the foraminous end region of the tube. The total area of the holes 94 was considerably greater than that of the bore area of tube 80. A sleeve 96 of 1/4 inch (6 mm) thick polyurethane foam material is fitted over foraminous end region of the tube 80.Visor noise does not present a problem when developing the diffuser; the low system pressure and large hose bores result in relatively low exit velocities from the diffuser holes 94. Consequently, a low foam density can be adopted in the sleeve 96.

The above apparatus provides an air-fed mask or visor system for a poratable spraygun which will deliver an ample quantity of breathable quality air when powered by a turbine unit such as the Sprayfine Cyclone. Filtration is effected by a replaceable respirator cartridge mounted in a chamber which in turn, is directy attached to the Cyclone unit. The air from the Cyclone unit is free from oil vapour so that the filter should have an extended life.

The air fed from secondary chamber 24 via opening 58 is cooler than that from the primary chamber 24 and after passage along a supply hose of the intended length is at an acceptable temperature for feeding to visor 88 whereas air branched from hose 54 or 74 would have been unacceptably warm.

Claims (11)

1. Respirator apparatus comprising: a source of air in high volume and at low super-atmospheric pressures comprising a housing having an air inlet, a turbine air compressor in the housing in communication with the inlet, a primary plenum chamber in the housing in communication with the discharge side of the air compressor for receiving the flow of compressed air therefrom, at least one outlet leading from the primary plenum chamber for discharge of a primary flow 6f air, a secondary plenum chamber in communication with the primary plenum chamber via flow restrictor means for receiving a secondary air flow from the primary plenum chamber, and an outlet leading from the secondary plenum chamber:: a filter positioned in communication with the outlet from the secondary plenum chamber for filtering the flow of secondary air; a flexible air delivery tube positioned in communication with a discharge side of the filter for receiving and conveying filtered air therefrom; and a helmet, mask or visor positioned in communication with an end of the flexible air delivery tube remote from the filter for receiving filtered air therefrom and having a face seal to prevent ingress of the surrounding air.

2. Apparatus according to Claim 1, wherein a small electric motor is connected to the turbine air compressor to drive said compressor.

3. Apparatus according to Claim 2, wherein the compressor, the primary and secondary plenum chambers, and the outlets from the primary and secondary plenum chambers are arranged so that in use air is present at the outlet from the secondary plenum chamber at a pressure of 2 to 3 psi (14 to 21 KPa) above atmospheric pressure.

4. Apparatus according to Claim 3, wherein said flexible air delivery tube has an internal diameter of at least 12 mm.

5. Apparatus according to Claim 4, wherein a visor tube having a foraminous end is positioned in said visor in communication with said end of the flexible air delivery tube remote from the filter for receiving air therefrom and a sleeve of plastics foam covers said visor tube.

6. Apparatus according to Claim 5, wherein portions of said visor tube define holes positioned along and around said foraminous end, an end of said visor tube remote from said hose is closed, and the sum of the areas of said holes exceeds the internal cross-sectional area of said visor tube.

7. Apparatus according to Claim 6, wherein in use the flow of air to said visor is at least 150 litres per minute.

8. Apparatus according to Claim 7, wherein the flexible air delivery tube comprises an upstream portion connected to a stub portion suspended by a manually releasable connector from a belt to be worn by the user.

9. Apparatus according to any preceding claim, wherein a primary outlet leads from the primary plenum chamber and a primary air delivery hose leads from the primary outlet to an air-operated device.

10. Apparatus according to Claim 9, wherein the air operated device is a spraygun.

11. Respirator apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.