Monday, April 24, 2017

Design Method for Aircraft Hangar Protection

NFPA 409, Standard on Aircraft Hangars defines hangar group classifications, construction features, and fire protection requirements for aircraft hangars. Group I and II hangars require foam and foam-water type systems.  The design the criteria for these is referenced in NFPA 409, Chapter 6. Determining the correct system design is essential to proper functioning of these systems.  In, Design of Special Hazard and Fire Alarm Systems, Robert Gagnon outlines a 12 step design method for aircraft hangar protection.

Step 1. Determine aircraft hangar group and select protection system type.
Each hangar group permits only specific types of fire protection systems designs. These options can include a foam-water deluge system, with underwing supplementary protection, automatic sprinkler with low-level foam, low-level high expansion foam, or a closed-head foam water system.

Step 2. Determine foam application time.

These times can vary based on the hangar group classification and foam systems utilized.
  • Low-expansion foam - 10 minute application time
  • High-expansion foam - 12 minute application time
  • Foam-water hand hose stations - 20 minute application time

Step 3. Determine system design density.

This will be based on the system coverage area, sprinkler spacing, type of foam used, and design density as outlined in the various component sections of NFPA 409:6.2.

Step 4. Estimate protection discharge rate.

Use the formula:
       D = (A) x (R)
D = foam solutions discharge rate, gpm
A= hangar floor area, square feet
R= application rate (from Step 3), gpm per square foot

Step 5. Estimate concentrate quantity for protection.

Use the formula:
    Q = (A) x (R) x (T) x (%)

Q= foam concentrate quantity, gallons
T= foam discharge time
% = concentrate percentage, decimal

Step 6. Determine aircraft wing area.  

Hangars that house aircraft having a wing area in excess of 3,000 sq.ft. are required to have supplementary under-wing protection. Without this under-wing protection the low-expansion foam system may be blocked from accessing the fire. The most common and effective supplementary under-wing protection is the use of oscillating monitors.

Step 7. Determine under-wing oscillating monitor location.

These should be located perpendicular to the fuselage to provide unobstructed protection beneath the wings.

Step 8. Determine oscillating monitor coverage area.

Monitors by different manufacturers will throw water in a certain radius and distance. When the radius is obtained the area of monitor coverage must be determined.  To determine coverage area use the following formula:
   Monitor area = [(3.1416) x (r2)] x (area of coverage/360)

Step 9. Apply oscillating monitor discharge time and application rate.

Discharge time is 10 minutes. Application rate is 0.10 gpm per square foot.

Step 10. Determine oscillating monitor discharge rate and concentrate quantity.

Use the formula:
   D = (A) x (R) x (N)
   Q = (A) x (R) x (N) x (T) x (%)

N = number of monitors installed

Step 11.  Determine supplementary hose discharge requirements.

A minimum of (2) hose lines at 60 gpm each for 20 minutes is required.

Step 12. Determine hose discharge rate and concentrate requirement.

Use the formula:
    D = (N) x (R)

    Q = (N) x (R) x (T) x (%)

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Friday, April 21, 2017

Fire Service Time Management [PODCAST]

Today's lean fire prevention organizations must function more effectively and efficiently than ever.  The key to achieving effectiveness and efficiency is time management. In his book, The Effective Executive, Peter Drucker provides a 3 step process for time management:
  1. Record time
  2. Manage time
  3. Consolidate time

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Monday, April 17, 2017

Time Management for the Fire Inspector

Today's lean fire prevention organizations must function more effectively and efficiently than ever.  The key to achieving effectiveness and efficiency is time management. NFPA 1730Standard on Organization and Deployment of Fire Prevention Inspection and Code Enforcement, Plan Review, Investigation, and Public Education Operations serves as a benchmark for the essential functions of a fire prevention organization or program.  Though, this standard requires only the essential items, even these can seem overwhelming to the understaffed, and overworked fire prevention organization. However, these, and much more, can be accomplished through the effective and efficient use of the inspectors time.  

In his book, The Effective Executive, Peter Drucker provides a 3 step process for time management:

  1. Record time
  2. Manage time
  3. Consolidate time
Time cannot be managed until it can first be found.  The first step toward time management is to record, track, and log how your time is currently being spent. The best way to accomplish this is through the use of a daily log. I always carry a notebook with me. I document every work task that I complete throughout the day. At the end of each day, I review where my time went that day and I prepare the next days schedule to determine where I want my time to go. At the end of each week I send out a an update e-mail on important projects and issues. This weekly activity provides another opportunity to review and evaluate where my time is being spent. At the end of each year I present all of our inspection data, numbers, and time to the department as bench-marking exercise.  Annually, our fire prevention personnel conduct a staffing/task analysis to determine what exactly is being done, how long it is taking to do, and if staffing levels are adequate. All these activities serve to ensure that our time is being used to its maximum potential.

After reviewing where our time is going, it must be managed. The best way to start managing your time is to diagnose and eliminate non-productive and wasteful activities. To determine if a task is non-productive, apply this 3 part 'diagnostic exam'.
  1. Does this activity need to be done at all? What would happen if it were never done again? 
  2. Can this activity be done by someone else? 
  3. Does this task waste other people's time?
Identify and eliminate those tasks that only serve to waste time and produce no results.  Only do the tasks that require you to do them, otherwise, delegate the task to others.  Eliminate those tasks that waste's others time, or find a more productive way to accomplish the goal, so that no ones time is wasted.

Finally, look at the time that you have and consolidate what is there.  This is commonly referred to as, "batching".  This is when you take the time available throughout the day, put that time together, and focus on specific task(s) completion.  It is best if this time can be uninterrupted.  Working in this manner is a more effective and efficient way of working than to jump from task to task, or working in spats of short time spans. For example, schedule all your plan reviews to be conducted on a certain day or portion of ("plan review day"), make one day your day for meetings, set aside a specific time to conduct inspections and stay within the geographical area. 

When considering time management for the fire inspector look to NFPA 1730. This standard provides a formula to determine the time requirements for common fire prevention tasks and demonstrates how to ensure that available time is being used most efficiently.

Monday, April 10, 2017

Agent Re-supply for ARFF Operations

How much fire extinguishing agent should an ARFF department have available? Is there a set amount of agent that is needed? What are some guidelines for determining agent quantity? 

NFPA 402, Guide for Aircraft Rescue and Firefighting Operations, acknowledges that it would be impractical to keep a stock of extinguishing agent on hand for the worst case scenario.  To mitigate any issue of an extinguishing agent shortage, pre-arrangements should be made.  Pre-fire plans and mutual aid agreements should detail the expectations for additional agencies to provide aid in the form of bringing additional agent to the scene.  Support should be requested early in an incident.

The initial water supply on a piece of apparatus should be assumed to be used up within 5 minutes of the incident. Based on the fact that ARFF apparatus carry enough agent (foam) for at least 1 water refill, NFPA 403, Standard for Aircraft Rescue and Firefighting at Airports requires 100% refill capability within the critical rescue and firefighting access area.

The critical rescue and firefighting access area is a rectangular area extending 500 feet out from the centerline of the runway, and 3,300 feet beyond each end of the runway. It is within this space that most aircraft accidents are expected to occur.

To determine the 100% capability a needs analysis must be conducted. All water sources and refill capabilities should be assessed. Recommendations for meeting the 100% refill requirements should be made.  These recommendations may include water sources from:

  • Tankers or structural equipment
  • Hydrants
  • Mutual aid agreements
The critical concern is that water is available to provide continuous attack to the fire until extinguished.

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