Hach 911 User Manual

Contents

Hach 911 User Manual Manual pdf 12 page image

10General InformationMulti-Conductor CableConductors may be part of a multi-conductor cable provided that all conductors within thecable are intrinsically safe. Each intrinsically safe conductor must have an insulationthickness of 0.25 mm (0.010 in.) which is rated for the maximum temperature rating of theapproved device to which it is connected. The intrinsically safe wiring must be color codedwith light blue, if no other wiring is light blue or appropriately tagged.SealsA seal must be provided at the point the intrinsically safe wire passes between thehazardous and non-hazardous locations to prevent the hazardous atmosphere fromentering the unprotected control room environment. The seal specification is that it mustnot pass more than 198 cm3 (0.007 ft 3) of air per hour at a pressure equivalent to 6 in.(1493 Pa) of water. While this is the same specification for the sealing requirements of anexplosion proof system, it may not be necessary to employ those seals.GroundingThe 911 and 940 Flow Meters and associated Opto-Isolated Interfaces do not requiregrounding or bonding. Under no circumstances should any attempt be made to ground orbond the 911 or 940 Flow Meters or Opto-Isolated Interfaces.2.1.5 Confined Space EntryImportant Note: The following information is provided to guide users of 911 and 940 FlowMeters on the dangers and risks associated with entry into confined spaces.DANGERAdditional training in Pre-Entry Testing, Ventilation, Entry Procedures,Evacuation/Rescue Procedures and Safety Work Practices is necessary to ensureagainst the loss of life in confined spaces.DANGERPour éviter les accidents mortels dans les espaces confinés, il faut organiser desformations supplémentaires dans les matières suivantes: Contrôle avant entrée,Ventilation, Procédures d'entrée, Procédures d'évacuation et de secours etMéthodes de travail sûres.On April 15, 1993, OSHA's final ruling on CFR 1910.146, Permit Required ConfinedSpaces, became law. This standard directly affects more than 250,000 industrial sites inthe United States and was created to protect the health and safety of workers inconfined spaces.2.1.5.1 Definition of Confined SpaceConfined Space is any location or enclosure that presents or has the immediate potentialto present one or more of the following conditions:• An atmosphere with less than 19.5% or greater than 23.5% oxygen and/or more than10 ppm Hydrogen Sulfide (H2S)• An atmosphere that may be flammable or explosive due to gases, vapors, mist, dust,or fibers• Toxic materials which, upon contact or inhalation, could result in injury, impairment ofhealth, or deathConfined spaces are not designed for human occupancy. They have restricted entry andcontain known or potential hazards.Examples of confined spaces include manholes, stacks, pipes, vats, switch vaults, andother similar locations.