A prototype active end-of-service-life indicator for respirator cartridges.
Maclay-GJ; Yue-C; Findlay-MW; Stetter-JR
Appl Occup Environ Hyg 1991 Aug; 6(8):677-682
A prototype device for indicating the end of service life of respirator cartridges was developed. The device consisted of a microsensor embedded in the charcoal bed of the cartridge that was electrically connected to a small low power producing module mounted on the face mask. The module triggered a flashing light emitting diode alarm that was visible to the user when 90% of the bed life was expended. The sensor consisted of a chemiresistor that was designed to produce a generic response to many of the contaminants that the face mask filter was supposed to remove and to operate at room temperature. It utilized a compensated bridge design to minimize the effects of changes in ambient temperature and relative humidity. The sensors were tested for their ability to respond to 100 to 4000 parts per million cyclohexane (110827) vapor. The initial response was rapid and the response time, defined as the time to reach 90% of the full signal, was on the order of 30 to 45 seconds. Relative response times as a percentage of the response time to cyclohexane measured for methylene-chloride (75092), benzene (71432), hexane (110543), carbon-tetrachloride (56235), acetone (67641), ethanol (64175), and methanol (67561) vapors were 100, 100, 85, 50, 5, 3, and 3%, respectively. The authors conclude that the prototype sensing system is an attractive and safer alternative to commonly used sensory warnings for indicating that the service life of respirator cartridges is approaching the end.
NIOSH-Publication; NIOSH-Grant; Respirators; Chemical-cartridge-respirators; Warning-devices; Cycloalkanes; Organic-vapors; Laboratory-testing; Respiratory-protective-equipment;
110-82-7; 75-09-2; 71-43-2; 110-54-3; 56-23-5; 67-64-1; 64-17-5; 67-56-1;
Respirator Research; Respirators;
Applied Occupational and Environmental Hygiene
Transducer Research, Inc., Naperville, Illinois