Gas sensing drift compensation using gas self-referencing for end of service life indication for respirators
First Claim
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1. An end-of-service-life indicator system for a filter cartridge for a respirator, comprising:
- a gas sensor;
at least two sample streams from the cartridge alternatively in fluid communication with the gas sensor; and
a valve controlling the flow from the at least two sample streams to the gas sensor, wherein the gas sensor compares the at least two sample streams;
wherein each of the least two sample streams samples from sample points within the cartridge and the sample points for the sample streams are located at different depths within the cartridge.
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Abstract
Embodiments relate generally to systems and methods for determining end of service life for a respirator cartridge by comparing the gas levels sensed at two or more sample points within the cartridge. Sample streams may run from the sample points to a gas sensor, wherein a valve may control the flow between the sample streams and the gas sensor.
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Citations
20 Claims
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1. An end-of-service-life indicator system for a filter cartridge for a respirator, comprising:
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a gas sensor; at least two sample streams from the cartridge alternatively in fluid communication with the gas sensor; and a valve controlling the flow from the at least two sample streams to the gas sensor, wherein the gas sensor compares the at least two sample streams; wherein each of the least two sample streams samples from sample points within the cartridge and the sample points for the sample streams are located at different depths within the cartridge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An end-of-service-life indicator system for a filter cartridge for a respirator wherein the cartridge has a forward end and a rearward end, comprising:
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a gas sensor; sample streams from at least two sample points in the cartridge to the gas sensor, wherein the gas sensor compares the gas level of the two sample streams, and wherein one sample point is proximate to the rearward end of the cartridge and another sample point is proximate to the forward end of the cartridge; and a valve controlling the flow from the at least two sample streams to the gas sensor, wherein the valve comprises; an air tight housing with an opening in fluid communication with the interior of a mask of the respirator and the breathing of a user, and a plurality of ports in fluid communication with the gas sensor and the sample streams, a diaphragm operable to move in response to pressure changes caused by the breathing of the user within the respirator, two or more seals operable to isolate a portion of the housing about one or more of the plurality of ports, wherein the seals are operable to control flow through the plurality of ports from the sample streams to the gas sensor, and an indexing mechanism coupled to the diaphragm and to the seals, such that movement of the diaphragm activates the indexing mechanism, thereby positioning the seals with respect to the plurality of ports and controlling flowfrom the sample streams to the gas sensor. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method of detecting effective-end-of-service-life for a filter cartridge for a respirator using a gas sensor for detecting gas levels comprising:
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receiving sample streams from at least two sample points in a filter cartridge, wherein the two or more sample points are located at different depths within the cartridge; alternating the flow from the sample streams to the gas sensor via a valve; and comparing the gas level present in the sample streams. - View Dependent Claims (18, 19, 20)
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Specification