What is Your Fire Panel Trying to Tell You?
By: Paul Holman, Project Manager, F.E. Moran Special Hazard Systems
In a perfect world, the Fire Alarm Control Panel (FACP) would be a system that only required attention during premeditated events such as a valve being closed off for system maintenance or for inspection and testing purposes. For many plant employees, it's "that control box on the wall" that nobody wants to manage. The alarm systems that control a power generating plant's fire protection systems can be confusing to the personnel who do not routinely operate and maintain them.
When operators do not thoroughly understand how FACPs function and do not know how to appropriately respond to their signals, the consequences can be devastating. Few emergencies in a power generating plant are more threatening than a fire condition. Fortunately, this scenario can often be avoided by educating plant staff about how to properly utilize FACPs.
Identifying Panel Types
The first step in understanding the functionality of FACPs is identifying the type of system that is utilized in the facility. Today's fire protection system control panels range from basic hardwired panels to the sophisticated addressable/intelligent type. Variables such as hazard type, age of the system and criteria required by the specifying engineer all influence the type of system that is employed.
Hardwired panels were the primary fire protection system controls up until the early to mid-80's when addressable/intelligent fire alarm systems made their entrance into the market. Hardwired systems relied on panel mounted modules that terminated circuits from groups of similar devices, such as a cluster of heat detectors over a Lube Oil Reservoir, or pull stations located at the egress doors from a Tripper Floor. Additional circuits would then connect to the alarm signaling audible/visual device, sprinkler riser switches (waterflow, tamper, low air pressure) and releasing solenoid valves, if applicable.
Comparatively, addressable/intelligent systems utilize significantly less wiring by using Signaling Line Circuits (SLC). The SLC is the heart of the addressable/intelligent fire alarm system, communicating with all of the input devices such as intelligent smoke detectors, addressable pull stations and relays and signaling circuit control modules over a common pair of wires.
All of these panels perform the same basic functions, but over time the competitive nature of the market has resulted in the evolution of FACP's capabilities with the introduction of new functions and features. Early FACPs performed basic functions such as: receiving alarm, trouble and supervisory signals; activating signaling circuits; energizing relays for equipment shutdown and closing fire doors. Addressable/intelligent systems have become markedly more powerful, capable of handling hundreds of devices, performing complicated functions through panel programming and providing system status via LCD screens.
It is common to find a sampling of different types of panels within a power generating plant. Because the panels may have been installed during different stages of time, it is not unusual to find everything from small hardwired FACPs to larger addressable/intelligent FACPs in the same facility.
Managing FACPs can be daunting if staff members do not fully understand how they operate and how to correctly interpret their signals.
The most prevalent systems that are found within power generating plants are hardwired panels because addressable devices typically do not meet the NEMA 4, 4X or explosion-proof standards for resistance to environmental elements and corrosion. Standard intelligent devices such as smoke detectors or manual pull stations are ideal for installation in locations such as Control Rooms, DCS Rooms, Switchgear spaces and offices, but are not designed for the severe environments, temperatures, humidity and classified areas where a coal belt, turbine underfloor or transformer reside. These harsh environments require rugged devices designed to withstand extreme conditions, which are then wired to an interface module that is located in a controlled environment. It is possible that the interface module is located in the same area as the FACP, or it can be housed in separate area, requiring additional wiring to connect the interface module to the FACP. This means that it is possible to have a powerful, addressable/intelligent panel, but all of the wiring may still originate out of the panel as though it was a hardwired FACP.
How do FACPs Work?
The early hardwired FACPs relied on internal jumpers and relay logic to perform any functions outside of basic general alarm, trouble or supervisory signaling. Over time, relay logic technology has been replaced with onboard programming through proprietary software that is installed from the fire alarm technician's personal computer. Using this software, the system can be manipulated to generate a specific reaction to various inputs. Latter generation hardwired FACPs incorporate microprocessor controls programmed through their keypads that incorporate basic logic programming, eliminating the need for relays and non-supervised internal interconnecting wiring.
In a typical day, an operator can encounter hundreds, or even thousands, of alarms in the power plant control room. The catalysts for these alarms vary in significance and it can be difficult to prioritize these alarms, especially if there is not an alarm management system in place. Deciphering FACP signals begins with understanding the basic Fire Alarm System messaging:
The FACP can be in any one or all four conditions simultaneously. In an ideal situation, only the green light will be illuminated, which means that there are no active alarms, system issues or supervisory signals on the panel. A yellow supervisory signal signifies an event such as an Outside Screw and Yoke (OS&Y) or Post Indicator Valve (PIV) that is in a closed position or a signal from a duct or gas detector. The other yellow light reveals system trouble and points to issues with the system's operation such as problems with hardware, software or the wiring from panel to field devices. It is imperative that system trouble signals are investigated and rectified as fire alarm signals may not be received if equipment is malfunctioning. Red fire alarm signals are the most critical alarms as they denote a fire situation that requires immediate action.
In addition to these basic signals, higher-end addressable/intelligent FACPs can have more advanced indicators on the panel such as: annunciate security inputs, a Special Hazard discharge indicator, a pre-alarm signal indicator, indications for silenced signal circuits and more.
Each signal is distinct for obvious reasons and demands that it is addressed accordingly in a timely manner. Unfortunately, service teams often arrive at a jobsite to find a FACP in alarm, trouble or supervisory mode, with the panel having been silenced and ignored. FACP signals are designed to mitigate risk and effectively notify staff about emergencies. Disregarding these signals thwarts the effectiveness of the FACP and puts plant assets and lives at risk.
Why do FACP Signals Go Ignored?
The reasons that these vital signals are often disregarded are abundant but they range from inadequately trained personnel to cryptic messaging. At times other tasks take precedence over attending to FACP alarms because staff members do not fully understand the gravity of some of the signals. The unavailability of spare parts for the system can also result in perpetually active alarms. Other explanations include vague drawings, lack of cable tabs for the system wiring and incomplete or missing operation and maintenance manuals. Some plants even bypass a relay or circuit so that production is not temporarily interrupted.
Educating Plant Staff to Successfully Manage FACPs
FACPs are implemented as a measure of protection to inform operators of potential or impending risks. However, when plant staff is not thoroughly educated about the functionality and associated indications of FACPs, the systems are rendered ineffective. Plant owners rely on operators to accurately interpret these signals and take immediate action to prevent issues from escalating. When signals do not receive timely response or they are overlooked altogether, risk levels are elevated
Putting a training program into practice is the best way to ensure that staff will understand proper protocol for various scenarios related to the FACP. A comprehensive curriculum should include areas such as: understanding hazards pertinent to the environment, identifying critical FACP components, FACP and valve operation and system programming. Whether staff simply need a review of FACP basics or in-depth instruction is necessary, having staff that is well-versed in these areas is a long-term investment. In the aftermath of a fire, it is too late to find out that a disaster could have been averted had plant staff fully understood the implications of an FACP signal.