PROTECTOWIRE FireSystems Special Hazard Fire Alarm Systems General Alarm circuits This section describes typical protective signaling systems which are consistent with NFPA standards and good fire alarm practices. We recognize that every risk area is unique and that the consulting electrical engineer may wish to modify a system to his special needs. We therefore urge the consultant to contact The Protectowire Company for assistance. Every panel is provided with one fire alarm indicating circuit. Additional supervised or unsupervised circuits of the capacity required may also be provided. Supervised 2-wire circuits are terminated in an end-of-line device. An open or a short in this circuit will cause an audible and visual alarm at the control panel. Special circuits which operate on a fire alarm signal may be provided to shut down fans or conveyors and to operate extinguishing devices, master boxes and other emergency equipment. Audible and visual signals actuated by fire alarms or trouble faults may be silenced and/or extinguished by operating the proper switch. The signal will then be transferred to the zone pilot lamp. After a detection circuit has been cleared of all faults the trouble signal will sound again to indicate the switch should be returned to its normal position. System operation Operation of any manual or automatic initiating device in a detection circuit will lock in an alarm condition to provide for continuous audible and visual indication. Control panels can be provided to accommodate the required number of initiating and indicating circuits. The Protectowire digital meter is an optional feature of the Protectowire system. Installed in the main panel, it provides a method of pinpointing the location of an overheated point on the Protectowire Linear Heat Detector. A Factory Mutual approved intrinsically safe fire detection system is available for protection of Class I, II, or III, Division I, Applicable Groups A, B, C, D, E, and G hazardous areas. This system incorporates voltage and current limiting intrinsic safety barriers installed in the control panel in series with the internal detection circuitry. The inclusion of this barrier is a cost-effective alternative to the use of explosion proof initiating devices and junction boxes. Alarm initiating zones Protectowire Linear Heat Detector Initiating circuit Each detection circuit is electrically supervised so that an open in the system wiring or in the alarm or trouble relay coils will cause a visual and audible indication at the control panel. An optional circuit may also be supplied which will provide a signal of a ground anywhere in the system. Each detection circuit is independent of all others so that an alarm or trouble signal in one zone will not prevent the receipt of either signal in another. Momentary initiation of the circuit will cause that zone to lock into alarm condition. All Class A detection circuits require four wires while Class B circuits may have a 2- or 4-wire loop. The latter type system will be terminated in an end-of-line resistor which may be placed at a remote location (2-wire loop) or at the main panel (4-wire loop). Depending on control panel selected, each circuit will accommodate up to 3,500 feet of Protectowire Linear Heat Detector (exclusive of hook-up wire) and up to 25 PRO-series smoke detectors or an unlimited number of contact devices. Figure 1 illustrates Protectowire Linear Heat Detector being used for cable tray protection. In this type of application the Detector will provide early warning of an overheating condition at any point along the cable tray run. Depending on control panel selected, circuits can control up to 3,500 feet of Linear Heat Detector. Protectowire Linear Heat Detector Protectowire Linear Heat Detector 190°F Figure 2 illustrates Protectowire Linear Heat Detector connected to a Factory Mutual approved intrinsically safe detection circuit for use in Class I, II, or III, Division I, Applicable Groups A, B, C, D, E and G hazardous areas. A conveyor run is used as an example of this type of protection. 280°F PWSC splicing connector Figure 4 illustrates Protectowire Linear Heat Detector rated for 190oF (88oC) and detector rated for 280oF (138oC) spliced in series. This is useful when the zone passes through a high ambient heat area which requires protection. Copper wire with standard or heat resistant insulation may be used in such areas if the ambient condition prohibits the use of Protectowire Linear Heat Detector. Protectowire Linear Heat Detector Figure 5 illustrates a zone where the alarm initiating devices are manual stations only. This could be used as a secondary alarm to actuate extinguishing material, shut down fans or for evacuation purposes. Any of these requirements may be integrated into detection circuits previously described when deemed advisable. Local energy master box connection Figure 3 illustrates cross-zoning using Protectowire Linear Heat Detector for Zone A and PRO-series smoke detectors for Zone B in the same area. Usually this arrangement is provided when the alarm initiating devices trigger automatic extinguishing agents. With this type of system the operation of extinguishing devices requires both zones to be in alarm. When the first alarm is received, a visual and/or audible signal is provided alerting operating personnel of a potential hazard. If the problem is not of a severe nature and personnel on duty can handle the situation, a second alarm may be prevented — eliminating the unnecessary automatic release of extinguishing materials. An optional time delay on the operation of the automatic extinguishing can be included to allow the operator time to manually abort the system if he determines that extinguishing is unnecessary. Care should be taken not to install smoke detectors where products of combustion emitted by manufacturing operations such as ovens, furnaces or welding may cause false alarms. The addition of manual stations to any of these circuits allows personnel to initiate an alarm. Litho in U.S.A. A circuit which supervises and trips a local energy or series master box may be supplied as part of the main panel or in a separate cabinet. Shunt type master box connection Proper relay may be installed in the control cabinet or in a separate cabinet to trip a shunt type master box. A lamp is supplied to indicate when the box is operated. Remote station connection Circuits of the reversed current type are available to transmit alarm and trouble signals to a remote location. Operation of extinguishing devices Electric solenoid valves may be operated from modules added to the panel to cause the release of extinguishing agents after the detection of a fire. Modules may also be provided to supervise tamper switches, low air, and other critical conditions. The Protectowire Co., Inc. Post Office Box 200, Hanover, MA 02339-0200 U.S.A. 781-826-3878, Fax 781-826-2045 Web: http://www.protectowire.com, e-mail: pwire@protectowire.com Special hazard fire detection systems DS 7858F-996