Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1997-12-12
1999-09-14
Lewis, Aaron J.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820125, 12820222, 12820523, A61M 1600
Patent
active
059506210
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a particular type of fan-forced positive pressure breathing apparatus, commonly known as Powered Air-Purifying Respirators (PAPRs). In particular the invention concerns monitoring the operation of such equipment.
BACKGROUND ART
Non-powered air-purifying respirator equipment involves a breathing mask having a filtered air inlet. Air is drawn through the filter by means of the wearer's breathing action. A considerable problem with this type of respirator is how to determine when the filter is due to be replaced. A number of "end-of-service-life" indicators have been proposed over the years, but none have been widely adopted. The major difficulty is that the useful life of the filter is determined by several non-related factors, such as the proportion of contaminant in the atmosphere, the humidity and the effort required of the user. Present estimates of filter lifetime are based on a number of such factors, and it takes considerable experience to weigh them together.
In recent years positive air-pressure respirators have been introduced, and these employ a pump which draws ambient air in through a filter and supply it to the face mask. The pump comprises a motorized fan which draws air through the filter in proportion to the speed of revolution. In such simple motorized equipment the filter life, in a particular environment, is directly related to the operating time and in practice can be estimated with reasonable reliability. However, these respirators suffer from the problems that they do not necessarily provide sufficient air flow for periods of maximum inhalation, but are otherwise wasteful in filter usage by providing excess flow during exhalation cycles.
A new generation of powered air-purifying respirators (PAPRs) that has been developed by the applicant employs a breathing demand valve to overcome the deficiencies of the simple positive air-pressure respirators mentioned above. However, the inclusion of the demand valve has reintroduced the unpredictable variant of air consumption into the determination of filter life.
DISCLOSURE OF THE INVENTION
In a first aspect, the invention provides a powered air-purifying respirator comprising: a face-piece to cover at least the mouth or nose of a wearer; a pump unit to supply ambient air to the face-piece via an air passage; a decontaminating means to filter the ambient air supplied to the face-piece; and a demand valve associated with the face-piece and responsive to a wearer's demand for air to deliver supplied air to the wearer. The respirator further includes data collection means to enable the volume of air drawn through the decontaminating means to be determined. This equipment takes advantage of the fact that the powered respirator has on-board power available to drive the data collection means.
The phrase "decontaminating means" has been used generically to indicate any means which is able to decontaminate the air for the wearer. The decontaminating means has been described with reference to a "filter" when that word has been used in a broad functional sense. It should be appreciated that the word "filter" also has a jargon meaning in this field to refer to a device for the mechanical removal of particles from the air; a filter usually comprises a fine mesh that will let air pass but not particles. The phrase "decontaminating means" also includes within its scope:
absorbers which suck up contaminants, like a sponge;
adsorbers to the surface of which contaminants adhere, for example carbon based gas filters; and
catalysts which transform a contaminant into a different material through a chemical reaction, for example "carbon monoxide filters".
The phrase "face-piece" has been used generically to indicate any apparatus which covers at least the mouth or nose of a wearer, and it includes a mask, hood or headpiece.
The data collection means may comprise a flow meter to measure the instantaneous flow of air within the respirator, and a clock. The flow meter and clock are operable to form an accu
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Berndtsson Goran Bertil Claes
Jervmo Bengt Yngve Roland
Klockseth Martinus Oliver
Lewis Aaron J.
Safety Equipment Sweden AB
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