Smoke Detector Placing for Magnetic Door Holders

Smoke Detector Placeing for Magnetic Door Holders

Smoke detector placement is important when designing a fire life safety system for obvious reasons.  In this article, we are going to focus on the smoke detector placement requirements per NFPA 72 2010 edition for smoke doors with magnetic door holders.  If you are using smoke detectors for the purpose of door releasing service than the following code shall apply:

NFPA 72 2010 edition:     

17.7.5.6.5.1 (A)
If the depth of the wall section above the door is 24 inches (610 mm) or less, one ceiling mounted smoke detector shall be required on one side of the doorway only, or two wall mounted smoke detectors shall be required, one on each side of the doorway.

17.7.5.6.5.1 (B)
If the depth of the wall section above the door is greater than 24 inches (610 mm) on one side only, one ceiling mounted smoke detector shall be required on the higher side of the doorway only, or two wall mounted smoke detectors shall be required, one on each side of the doorway.

17.7.5.6.5.1 (C)
If the depth of the wall section above the door is greater than 24 inches (610 mm) on both sides, two ceiling mounted smoke detectors or two wall mounted smoke detectors shall be required.  One on each side of the doorway.

In the above picture, you can clearly see that the header or space above the doorway with magnetic door holders is less than 24 inches (610 mm).  However, the installing fire life safety company installed a smoke detector on the ceiling on both sides of the doorway.  This smoke detector placement is not required but it never hurts to have extra coverage.  Just thought I would point it out.

Conventional or Addressable fire alarm system

Which is better, conventional or addressable fire alarm system

A fire alarm system has a number of devices working together to detect and warn people through visual and audio appliances when smoke, fire, carbon monoxide or other emergencies are present.

Choosing a fire alarm system isn’t just about adhering to legal requirements; it’s also about saving time, money and effort.

A Fire Alarm Control Panel (FACP), or Fire Alarm Control Unit (FACU), is the controlling component of a Fire Alarm System.

Regardless of the type of system installed, all have to meet the National Fire Protection Association (NFPA) codes, local regulations, and the NBC Part 4 Life Safety Code enforced by the authority having jurisdiction (AHJ).  All commercial buildings are required to have a code compliant fire alarm system, the best way to ensure proper installation is to hire a licensed integrator with knowledge and experience.

The most common types of alarms that businesses use are conventional and addressable alarm systems.

Both types of alarm link devices (such as call points and smoke detectors) to a main control panel. The main difference between the two is that with addressable fire alarm systems, you can pinpoint exactly which device has been activated.

Conventional Fire Alarm

The conventional fire alarm system is based on analog electrical system. It is an old system usually installed in small offices or homes.

The main difference is the configuration or the connection of the devices with the main control panel. There is a separate circuit or wired connection for each device.

Since there are separate wires for each device, the cost for cables and the installation cost is relatively higher than addressable fire alarm. But the main control panel is quite simple and cheap which reduces the overall cost of the conventional fire alarm. Therefore they are used in business having smaller building sizes and lower budget.

Each circuit connected with the main panel is used for monitoring a specified area known as zones. For example, each floor of a multi-storied building can be divided into zones. Each floor has multiple sensors and detectors connected with the main control panel through a single circuit.

Since it cannot pinpoint the exact location of the fire in the building, it is difficult for fire fighter to find the exact location and extinguish the fire before it cause further damage. In case the device connected in a circuit stops working or if the wire of the circuit breaks, it is quite difficult to spot the fault. You need to check each device in the circuit to spot the faulty one.

Addressable Fire Alarm

As the name suggest, the addressable fire alarm system assigned each individual devices a unique address. It is a digital updated version of the conventional fire alarm where each detectors or sensors have unique identity. Therefore, each device has its own identity which makes it easier to identify which device has been triggered and spot the location of fire. The system quickly notifies the local responders to take the necessary action to stop further damage.

The wiring of addressable fire alarm is very simple. They are connected in a single loop thus saving the cost of wiring and installation. However, the equipment used is quite expensive and the initial cost of the system is quite high. Therefore, such systems are suitable for large buildings having many rooms and have high budget.

It is a digital system with a digitally programmable main control panel that allows to program the threshold of the detectors. This feature allows it to be used in any kind of environment and prevent any false alarm that could end up wasting first responder’s resources and affect the business.

Apart from that, the control panel can detect any faulty device and its exact location in order to replace or troubleshoot the said device. The smart programmable control panel can also be programmed to detect any potential fire hazard (such as gas leaks) and notify the personnel to remove it before the buzzer is triggered. Since the detectors are connected to the main panel through both ends of the wire, break at one end of the wire will not affect its operation as it can send the signal through the other end. This feature makes it more reliable than conventional fire alarm.

How do addressable and conventional alarms differ? 

Every device connected to the addressable system has its own unique address. When a fire is detected, the device’s address shows up on the main control panel, telling you exactly which device has been activated. This will enable you to find the exact location of a fire and extinguish them quickly.

With a conventional system, there is no way of pinpointing the exact location of the fire. However, by wiring your building into different zones, you can get a general idea of where the fire is. For instance, if you have two floors, you could wire the first as ‘zone 1’ and the second as zone 2. So if a fire occurs in zone 1, you know that the fire is somewhere on the first floor.

Wiring differences

Addressable alarm systems connect devices using a Loop. This is where one wire connects all devices to the control panel. Both ends of the wire loop connect to the control panel.

With a conventional alarm, each device will be connected to the control panel via its own wire, rather than a shared one. One end of the wire will be touching the device, and another touching the control panel. 

Which is the cheaper option for you? 

Conventional alarm panels cost a lot less to buy but are more expensive to install. This is because each device that is being connected needs its own wire. With addressable systems, one wire loop will connect several devices. This means conventional systems require more wire and more man hours during the installation phase.

Additionally, addressable systems have a range of other facilities that can help save money. For instance, addressable alarm panels monitor the air flow through smoke detectors to prevent the occurrence of false alarms, which can be costly to a business.

Conventional fire alarm India cost a lot less to buy but are more expensive to install. Because all the devices connected to the control panel needs its own wire. With addressable systems, several devices can be connected to the control panel with one wire loop. This means conventional systems require more wire and more man hours during the installation phase.

Following comparison table shows the key differences between addressable and conventional fire alarm systems.

Conventional Fire Alarm	Addressable Fire Alarm
The fire alarm system where the each detector is connected using separate parallel circuit to the control panel.	The fire alarm system where the detectors are connected using a single loop of wire to the main control panel.
The detectors inside a circuit cannot be distinguished from each other.	The detectors are assigned with unique binary address.
There are 1 or more than 1 circuits.	There is only one circuit.
It requires more wires to connect each device.	It require less wires as it uses only one circuit.
It cannot pin point the exact location of fire in a building.	It can pinpoint the exact location of fire.
The main control panel is not programmable.	The main control panel is programmable.
The alarm signal is sent using an analog electrical signal.	The alarm signal is sent in a digital binary form.
The detector’s threshold cannot be programmed.	The detector’s threshold can be programed according to the environment.
It is more affected by false alarms.	it nullifies any false alarms due to its programmable features.
There is no such warning feature for potential fire hazard.	It carefully monitors and based on smart decision send warning for potential fire hazard in a specific location.
There is no RTC (real time clock) chip.	The RTC chip offer a. event log for analysis.
The Conventional alarm system is less reliable.	The addressable system is far more reliable than conventional system.
The installation takes many labor hours and cost more than addressable fire alarm.	The installation is easier and can be quickly installed with minimum investment.
The overall equipment used in conventional fire alarm is very cheap.	The overall equipment used is very expensive.
It is used for small offices or building where such smart system is not necessary.	It is used for large buildings with business where they can’t afford to lose any time.

Overall, the conventional fire alarm is inexpensive and used in small building. however, the addressable fire alarm is very smart and sophisticated system which is very expensive but it is more reliable. Bottom line, conventional fire alarm should be  installed in building where it is easier to spot the fire (such as in building having fewer rooms) While the addressable fire alarm should be installed in large buildings.

Which is more reliable?
The addressable alarm panel is also the more reliable of the two. This is because the wire connects to the control panel at both ends (see the diagram above). If one end of the loop becomes severed, signals can still be sent to the control panel via the other end of the loop. Loop isolation modules are also used to separate devices on the loop. This means that if one device becomes disconnected, it won’t disable the circuit. With a conventional system, if a wire has become severed, the device will become disconnected.

Overall

The most obvious difference between the two, in terms of installation, is cabling requirements and labor costs.  Due to the fact that addressable systems require less cabling they make for less complex installations.  Functionally, the addressable fire alarm unit is superior, which can help prevent costly activities and save time when detecting a fire. It’s also cheaper and easier to install. But in terms of buying price, a conventional system is cheaper, and will meet the functional needs of small premises where a sophisticated system is not necessary.

Functional Safety Audit & Assessment

Don’t Confuse a Functional Safety "Audit & Assessment"

UNDERSTAND THE CRITICAL DIFFERENCES BETWEEN THE TWO ESSENTIAL EVALUATIONS

Many people working in safety instrumented system (SIS) project development, execution, operation and maintenance treat a functional safety audit (FS Audit) and a functional safety assessment (FSA) as one and the same. So, based on this assumption, they simply ensure that such an activity is undertaken and perhaps signify the need to perform this evaluation at some point when it appears as a milestone on the project schedule. Moreover, often they call upon someone working on the project,
who may or may not have had some previous experience in quality auditing, to deliver this audit/assessment. However, this is not a reasonable approach because the concepts for the audit and assessment markedly differ.

An FS Audit provides a systematic and independent examination of the particular safety lifecycle phase activities under review. It determines whether the “procedures” specific to the functional safety requirements comply with the planned arrangements, are implemented effectively, and are suitable to achieve the specified objectives.

Industry good practice is encapsulated in the IEC 61511 standard. Its clause 5.2.6.2.1 notes: “The purpose of the audit is to review information documents and records to determine whether the functional safety management system (FSMS) is in place, up to date, and being followed. Where gaps are identified, recommendations for improvements are made.”

This review of the FSMS process essentially focuses on the procedures that shall be defined and executed at the time of the project schedule/associated execution activities and, as a result, the following management activities should be in place:

• FS Audit strategy;
• FS Audit program; and
• FS Audit plan, reporting process and follow-up mechanism.

So, in essence, the process and expectations of an FS Audit resemble those of a normal project quality management system (QMS) ISO 9001 audit regarding a “systematic review” of the execution strategy being applied. [For details on the latest edition of ISO 9001.

This usually means the QMS department (with support from the project safety team) performs the FS Audit. People in that department have the relevant audit skills to verify that procedures, forms and templates that constitute the contents and requirements of the FSMS are being correctly implemented. Functional safety competency is not a primary skill-set requirement for them.

An FS Audit is undertaken to ensure compliance with procedures. Auditors do not assess the adequacy of the work they are auditing and do not make specific judgments about functional safety and integrity.

In contrast, an FSA is an independent in-depth investigation into the previous and current lifecycle phase activities based on evidence, aimed at evaluating whether functional safety has been achieved. FSAs rely heavily on assessor judgements and competency. One of the inputs to the FSA process is the FS Audit processes and findings.

As with the FS Audit, there are requirements to formalize a procedure for how this activity shall be defined, executed and planned into the project schedule. However, that’s where the similarity in approach and delivery ends. For an FSA, the focus is on “judgement” about the functional safety and safety integrity achieved by the safety-related project activities under assessment. Its goal is to ensure that functional safety has been achieved within the specific scope of supply for the organization(s) under assessment and in the context of the safety lifecycle.

The safety-related-systems project team implementing one or more phases of the functional safety lifecycle should plan FSA activities, but independent resources with the necessary competencies and SIS application skill set should execute the activities. Note that the FSA team undertaking the assessment must include at least one “senior competent person.” Often, two assessors form the assessment team to ensure the necessary depth and rigor for subject matter coverage.

The two key international safety standards — IEC 61508 [2] and IEC 61511 — cite requirements on how and when to execute one or more FSAs. For IEC 61508, this is Part 1 clause 8, and for IEC 61511 Part 1 clause 5.2.6.

Performing FSAs requires staff with a high level of competency and more often than not relies heavily on subjectivity, particularly when applied to earlier phases of the safety lifecycle.

The FSA activity is a mandatory (“shall”) requirement for claiming compliance to either of the safety standards; justifying such a claim requires documented evidence of an adequate FSA.

Besides helping to satisfy the standards, an FSA usually provides tangible benefits in terms of functional safety assurance and avoidance of costs and resource issues regarding potential rework at later lifecycle phases.

Planning Your FSA Requirements

Two points in the standards bear stressing: FSA requirements apply to all phases throughout the overall safety lifecycle; and the organization performing the FSA (and by implication its assessors) must meet a defined level of independence.

Keeping those points in mind, before embarking on developing an FSA methodology, you must consider:

• which IEC safety standard is being used for the development of the FSA process;
• the organizational and management models operating within the company and how these impact the levels of independence;
• the availability of “competent” resources and the necessary documented
evidence to support the standard’s requirement regarding competency
assurance;
• the role of the FSA requirements within the supply chain
and who is managing the overall activity across the various
organizations;
• the level of planning required, which depends upon
the size of the project, e.g., whether it involves a large capital
expenditure (capex) or a small modification to an existing operational
SIS; and
• optimizing the number of FSA stages and individual FSA phases within each stage regarding the overall cost of safety

A typical capex safety project likely will require more than one FSA. This will depend upon:

• the specific safety lifecycle phase(s) under assessment;
• the duration of the project and operation-and-maintenance lifetime;
• the number and type of safety systems implemented within the project;
• the degree of commonality across the technology solution; and
• the requirements for SIS management of change/modification covering the initial project and the entire SIS mission time.

Therefore, the person with lead responsibility for FSA planning and
execution within the organization that will manage the FSA requirements
must prepare a “functional safety assessment plan” for the safety
project and ensure this appears as a featured “milestone” on the overall
SIS project schedule/plan.

The FSA plan must be written to enable performing a systematic and comprehensive FSA (or a number of FSAs). It must specify:

• the stage(s) within the safety lifecycle when the FSA(s) will occur;
• the schedule and estimated duration of the assessment(s);
• the scope of the FSA(s) to be planned;
• the membership of the assessment team at each FSA stage;
• the degree of independence in accordance with IEC 61508/IEC 61511;
• the skills, responsibilities and authorities of the assessment team;
• the information that will be generated as a result of the FSA;
• the identity of any other safety bodies and departments involved in the assessment;
• the documents referenced at each FSA stage;
• the findings and recommendations from each FSA stage;
• follow-up and corrective action resolution; and
• FSA closure and management of continuous improvement/learning.

At some point in the planning process, the FSA plan will need to be approved by the responsible manager and issued to all parties prior to the assessment. Typically, only one plan is developed for the specific project FSA stages and phases. The individual phase reports effectively become a “living document.” After completion of each phase, evidence is reviewed, and findings, conclusions and recommendations are added to the FSA report to provide the necessary forward/backwards traceability for the assessment process.

Ongoing operational modifications of a smaller nature associated with an installed SIS may not need such regimented formal planning. However, IEC 61511 clause 17.2 requires implementation of some level of planning and verification for any such modifications. More importantly, the proposed changes shall not take place until completion of an appropriate FSA and receipt of proper authorization.

The Essentials Of Performing An FSA

The FSA must address the appropriate part(s) of the safety lifecycle in accordance with the recommended stages in IEC 61511 (see Part 1, Figure 7 — SIS safety life-cycle phases and FSA stages). Essentially, the FSA will review within the lifecycle activities under assessment if
appropriate methods, techniques, competencies, results and processes have been used to achieve functional safety.

The FSA, dependent on the applicable scope and the necessary backwards traceability at the time of the assessment, should check among other things that:

• The SIS has a defined and well-documented concept, hazard and risk identification, and risk reduction allocation to allow it to be designed, constructed, modified, verified and tested in accordance with the hazard and risk assessment, safety requirements specification, functional design specification, installation and commissioning safety acceptance test and eventual operation and maintenance of the SIS (not forgetting that the FSA also applies to part or full decommissioning of
any installed SIS).
• Regulations, mandatory standards and any stated codes of practice have been met and evidence of the requirements is available as part of the safety manual for the project/modification.
• The safety lifecycle activities under assessment have appropriate validation planning in place and the validation activities have beencompleted.
• Adequate and complete documentation is provided throughout and, in particular, the necessary independence is evident between authors, reviewers and approvers.
• Project change-management procedures are in place and have been applied throughout the lifecycle
phases. (There should be evidence of impact assessments, technical project queries, approved solutions and verification specifications, test planning and test records inclusive of document/records analysis and final approvals.)
• The safety integrity level (SIL) for each defined safety instrumented function (SIF) “achieves” and continues to “maintain” the SIL target requirements from design into operation and
maintenance.
• Any support, calculation, development and production tools used have been included in the FSA and have been assessed as being fit for purpose, e.g., “T classification” for support tools in
accordance with IEC 61508.
• Disparities within any of the lifecycle activities have been identified and resolved to ensure functional safety has not been compromised.

Use of specific checklists usually can assist the assessment team in focusing on the key areas to be covered during the required FSA(s). Such checklists are geared towards achieving the necessary functional safety requirements linked to the specific clauses and requirements of the IEC standards. This provides the basis for a robust assessment structure and enables the assessment to build upon a common format, e.g. structured observation recording, and by association, to develop the necessary traceability.

Such checklists:

• provide assessment enquiry consistency regarding project documentation to be presented that is necessary for the safety system being produced;
• support the focus on any shortcomings in requirements, design, implementation or procedure identified by the assessment process; and
• act as an aide memoire to ensure critical appraisal of all aspects of the project. This would be based on the assessment team judgment regarding the questions being raised and their relationship to the particular safety lifecycle activities under assessment.

An important underlying question is who in the organization manages the overall requirements for FSA deliverables and assigning the lead FSA role to a “competent” person? Is there evidence available to support any specific FSMS FSA training and mentoring processes applied for those
“approved” to conduct such FSAs?

What Is The Benefit?

Experience teaches that FSAs can reveal real errors and deficiencies in processes, technical capabilities and alignment with the safety requirements for either the new build or installed operational SIS. These are lapses and omissions that almost certainly would go undetected
in an FS Audit.

Here are only a few examples as found on a number of end-user delivered FSA assignments:

• Insufficient independence between protection layers that is not revealed and not acknowledged during the process of safety function allocation to protection layers, thus leading to inappropriate SIF
requirements and the wrong target SIL.
• Management-of-change issues caused by a loss of system “freeze’ for SIS modifications, resulting in different teams working on differing versions of SIS documentation and associated common SIF modification requirements.
• Lack of substance in change management “impact assessments,” leading to changes being
approved that potentially compromise both safety functionality and safety integrity.
• SIS corrective maintenance that has evolved to a “modification” without supporting impact assessment and document revision controls.
• Real discrepancies and misunderstanding between SIF device response times (DRTs) and overall process safety time (PST), resulting in non-compliant PST claims.
• Deviations in device safety manuals and, by detailed review of supporting device certification
reports, identification that purchased devices do not meet the application and operating environment requirements for use.
•Inadequate hardware reliability calculation where the use of too low failure rates results in too low average probability of failure on demand achieved and omission of compliance with systematic capability requirements, both leading to higher claimed SILs than in reality
• Conflicting specification requirements for both application program
“destruct” and “construct” using the same field devices and input/out for different SIF requirements.


And just for good measure, let’s not forget the FS Audit and FSA time-honored systematic capability chestnut:
• Identification of document and test “authors,” “reviewers” and “approvers” being one and the same person.

Perform A Proper FSA

Shortcomings in planning and executing the FSA process during different stages of the safety lifecycle can contribute significantly to potential SIS failures during the operational lifecycle phase. So, organizations involved in and responsible for the management of any stage of the safety lifecycle of the SIS must ensure the execution of such FSAs rests with assured competent resources. This will form part of the company FSMS and will support the systematic capability for the specification, design, engineering, operation and maintenance of a SIS.

In some cases, FSAs can span several organizations and the FSA activities will require overall management control because they can drill down to specifics, technicalities and results of any verification and validation. Therefore, they should have the relevant senior management support across the supply chain involved for reserving the right to re-do activities where functional safety may be compromised.

In considering industry good-practice expectations, performance of such FSAs should comply with the IEC 61508/IEC 61511 safety standards, which demand prescriptive independence and a high level of competency assurance. For more on FSAs, see Reference 3.

REFERENCES
1. “Functional Safety — Safety Instrumented Systems for the Process Industries Sector,” IEC 61511, 2nd ed., Intl. Electrotechnical Commission, Geneva, Switz. (2016).
2. “Functional Safety of Electrical/Electronic/Programmable Electronic Safety-Related Systems,” IEC 61508, 2nd ed., Intl. Electrotechnical Commission, Geneva, Switz. (2010).
3. Nunns, Stuart R., “Functional Safety Assessment: Setting the Boundaries of the FSA, Defining the Scope and Planning the FSA,” ABB, St. Neots, U.K. (2009),