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Publication of GB254299ApublicationCriticalpatent/GB254299A/en
Respiratory Apparatuses And Protective Means
(AREA)
Abstract
254,299. Deutsche Gasgl³hlichtauer Ges. June 27, 1925, [Convention date]. Respirators.-In devices for indicating the presence of moisture or other impurities or additions in gases, such as air passing through a breathing filter, or for controlling devices in such presence, the moisture &c. acts directly upon a test substance which crumbles or disintegrates due to the alteration in its chemical or physical state and not to fusion or destruction by heat, and which thus causes or permits the mechanical actuation of the indicator &c. A brick of test substance may be mounted in the breathing filter in or behind catalysts for the oxidation of carbon monoxide to indicate when the catalysts are becoming inoperative due to absorption of moisture, the brick crumbling due to exposure to water vapour at a pressure above that harmful to the catalysts and in quantities sufficient to render the catalysts inoperative. A brick of compressed calcium carbide powder may, on crumbiing, close a spring-loaded valve and warn the user of the filter by a change in the air pressure. The Specification as open to inspection under Sect. 91 (3) (a) comprised also a breathing filter with a brick of hygroscopic substance. This subject-matter does not appear in the Specification as accepted.
Filter media comprising a filtering agent effective for removal of cyano-containing contaminants having improved compatibility with amine-sensitive impregnants and amine-sensitive substrates