Stand-alone Gas Monitoring and Alarm System with Automatic Calibration - Rel-Tek Corporation - #1

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Specification: Stand-alone Gas Monitoring and Alarm System with Automatic Calibration1. General Operation - Gas Monitoring System (GMS) is a stand-alone gas detection and alarm system designed for monitoring small garages and buildings where hazardous gases may develop. A central control panel powers and monitors up to eight combustible gas sensors, while providing automatic calibration of the sensors on a scheduled basis. The control panel contains all necessary electronics, power supplies, processors and other components essential to the normal GMS operation and alarm determination, while a second panel, with associated cal-gas tanks and gas distribution tubing, provides the automatic calibration utility. Alarm(s) with strobe and horn are activated to alert workers of a hazardous condition. Relays are included for activating external electrical devices such as ventilation fans and louvers, and for transferring alarm status to a separate security or fire alarm system. 2. GMS Components - In view of the various gas densities involved and the various safety functions served, the placement of sensors and other system components is established by the cognizant architect and/or engineer. The sensors are usually wall mounted, or hung from conduit. Control panel(s) and alarm(s) are intended for wall mounting at easy viewing height, usually five feet above floor level for control panels, and 10’ or higher for alarms. Each alarm unit is equipped with a strobe and horn: the strobe is normally activated at a low urgency gas alarm threshold and both strobe and horn activated at a high urgency gas alarm threshold. Emergency stop (ES) and alarm reset (AR) switches are installed on the controller, while additional ES and AR switch boxes may be added for remote locations. Temperature regulation shall be incorporated to avoid problems with temperature, condensation, etc.3. Siting equipment for safety-There are presently no areas of the site which are designated as hazardous, however, the central control panel supplied must be approved to UL-508 (Industrial Control Equipment.) All GMS components, including the alarms and switches are installed in fresh air areas. Installation and wiring shall conform to NFPA-70 (NEC).4. Gas Sensors
a) All sensors- Sensor components shall be of non-corrosive construction.Excitation shall be 24-28VDC, drawing not more than 80 ma. The analog output shall be 4-20ma (linear). Zero and span adjustments shall be readily accessible. A test jack shall also be readily accessible for test monitoring the 4-20ma output signal using a portable milli-ammeter; a mating connector and harness shall be supplied. Using the test jack and/or implementing automatic calibration will automatically disconnect the sensor signal such as to avoid any alarm actions while testing or calibrating. Sensor output shall be linear and accurate to within +/-5% of FS over an ambient temperature range of 32-110F and humidity of 5-95% RH, excluding condensation, while subject to proper maintenance.Initial power-up of sensors shall not cause overshoot or alarms. Sensors shall be calibrated after installation in accordance with SUPPLIER’s instructions and at least monthly thereafter, to assure continuing accuracy and reliability. Sensors shall be