Laserfiche WebLink
9 <br /> <br />o. The demand valve shall use an extended temperature range dynamic O-ring seal <br />composed of a fluorosilicone elastomer. <br />p. The diaphragm shall include the system exhalation valve and shall be constructed <br />from a high strength butyl elastomer. <br />q. A purge valve shall be situated at the inlet of the breathing regulator and shall be <br />capable of delivering airflow of between 125 and 175 standard liters per minute. <br />r. The breathing regulator shall be arranged to direct the incoming air over the inner <br />surface of the facepiece for defogging purposes. <br />s. The components of the breathing regulator shall be constructed of materials that are <br />not vulnerable to corrosion. <br />t. The flame resistant cover shall contain an air saver switch and pressure demand <br />bias mechanism. <br />u. It shall reactivate and supply air only in the positive pressure mode when the wearer <br />affects a face seal and inhales. <br />v. This device shall not affect the breathing flow through the system while in operation. <br /> <br />C. Pressure Reducer with CGA Cylinder Connection: <br />a. The pressure-reducing regulator shall be mounted at the waist on the backframe <br />and be coupled to the cylinder valve through a short length of internally armored <br />high pressure hose with a hand coupling for engagement and sealing within the <br />cylinder valve outlet. <br />b. In lieu of a manual by-pass, the pressure-reducing regulator shall include a back-up <br />pressure-reducing valve connected in parallel with the primary pressure reducing <br />valve and an automatic transfer valve for redundant control. <br />c. The back-up pressure reducing valve shall also be the means of activating the low- <br />pressure alarm devices in the facepiece-mounted breathing regulator. <br />d. This warning shall denote a switch from the primary reducing valve to the back-up <br />reducing valve whether from a malfunction of the primary reducing valve or from low <br />cylinder supply pressure. <br />e. A press-to-test valve shall be included to allow bench testing of the back-up <br />reducing valve. <br />f. The pressure-reducing regulator shall have extended temperature range dynamic <br />O-ring seals composed of fluorosilicone elastomer. <br />g. The pressure reducing regulator shall have incorporated a reseatable over- <br />pressurization relief valve which shall prevent the attached low pressure hose and <br />facepiece-mounted breathing regulator from being subjected to high pressure. <br /> <br />D. End-of-Service Time Indicator (EOSTI): <br />a. The SCBA shall have two end-of-service time indicators (EOSTI). A tactile alarm <br />and a Heads-Up Display (HUD). <br />b. The primary EOSTI shall be the integral low-pressure alarm device that shall <br />combine an audible alarm with simultaneous vibration of the facepiece. <br />c. The primary EOSTI shall be located in the Facepiece-Mounted Positive Pressure <br />Regulator. <br />d. This alarm device shall indicate either low cylinder pressure (33%+5%, -0%) or <br />primary first stage regulator failure. <br />e. The HUD shall serve as the secondary EOSTI indicator. <br />f. The HUD shall be powered by the SCBA’s single power supply. <br />g. It shall be mounted in the user’s field of vision on the Facepiece- Mounted Positive <br />Pressure Regulator. <br />h. It shall display cylinder pressure in increments of 100%, 75%, 50% and 33%. <br />i. The display shall not have a numerical representation of bottle pressure. <br />6.1.D. - Page 11