Fire Protection Resources

Who Needs a Fire Monitoring System?

Fire Monitoring is a requirement that comes from the National Fire Protection Association (NFPA 13,) it states that if a system has more than 20 heads, it should be monitored by a Remote Central Station. Once a Fire Monitoring system is installed in a building, it must stay operational for the duration of the life of the building.

General Description of “Fire Monitoring” System:
Monitored system means a “Remote Central Station” receives specific signals from the installed system and dispatches the Fire Department upon receipt of an “Alarm signal” or, advise the service vendor of any “Trouble signal” that may occur. Basic and minimum systems consist of connections to the Fire Sprinkler System only; if other systems are installed in the building (i.e. Elevators, HVAC – of a certain size, FM-200 or Pre -Action) they must be connected to the Monitored System as well.

System Requirements

  • Power: System should have its own dedicated 110 Volt 20 Amp breaker. Breaker shall be locked & permanently marked as “Fire Alarm”.
  • Communication Path between the Fire System to the Remote Central Station:

Due to major changes in the Telecommunication world, the code is adjusting requirements and adopting new and different types and styles of communication paths to the Central Station. Since landline, copper phone lines are being phased out, additional acceptable methods (other than 2 phone lines) include: Radio, IP, and Cellular service, the equipment must be LISTED for its intended use.

  • What needs to be monitored:

According to NFPA 72 (Fire Alarm standard) the System should send the following signals:
General Alarm – Caused by the activation of any device connected to the system: i.e. Pull Station, Smoke Detector, Flow Switch, etc.
General Trouble – Any type of power loss, low battery, cut wire, ground fault, etc.
Supervisory – Condition that indicates that one or more Sprinkler Valve is in the “Closed” position).

  • Location of Main Monitoring Panel:

Several locations are usually acceptable: Electrical/ Telephone Room, by the Main Sprinkler Riser, or sometimes in the Main Lobby. Locations depend on different factors such as, Fire Department requirements, Owner or Architect preferences, and availability of physical space.

  • Plans, Permit & Inspection:

Most cities require plan check and an installation permit for a Fire Monitoring system (even for an existing building); permit fees vary depending upon City and type of system installed.

  • Fire Department Has The Final Say! 

All the information listed above is correct for most localities; however, the Local Fire Department will always have the “Final Say” about the final system (i.e. the type installed, what will be connected, if additional devices are required, etc.) Each and every Fire Department has their codes that must be followed. Remember what is required in one City, may not be what is required in another. Regency is the best place to help you decided what system is best for you!!

Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems

By Hansford Stewart

It’s the first day on the job as a new inspector and you show up at the installation for the inspection and annual test. All of the records, including the certified factory test curve, instruction manuals, and annual test results, have disappeared faster than Mona Lisa’s smile in a Daniel Brown novel. You look over the installation and are amazed that this equipment can even operate, let alone provide water under pressure, during a demand situation.

NFPA 20 requires that the fire pump equipment be protected from possible interruption of service through damage caused by explosion, fire, flood, earthquake, rodents, insects, windstorm, freezing, vandalism… obviously, we should have included walls falling on the equipment. It is interesting to note that the only item left standing was the fire pump.

Wall collapsed on Fire Pump Equipment

Wall collapsed on Fire Pump Equipment

Automatic fire pump systems are very reliable and have been a key factor in reducing property damage and the death rate in commercial and residential applications. When they fail, it is usually because they have not been maintained, inspected, or tested in accordance with NFPA 25. NFPA 25, Chapter 8 provides minimum requirements for inspection, testing, and maintenance of fire pump assemblies. Let’s take a look at some of the key items covered by this standard.


Obviously, the purpose of the inspection is to verify that the pump assembly is in good working order and is free from physical damage. It is important to notify the supervisory service before conducting any test or procedure that could result in a false alarm.

This is not an inclusive list of items to be inspected, but includes many important considerations:

Coupling Alignment:
Coupling alignment is a critical item and should be checked annually. Many factors can affect alignment, such as thermal expansion and maintenance on the equipment. If the equipment is out of alignment, it could cause premature failure and possible disruption of service.

Circulation Relief Valves:
NFPA 20 5.11 requires that electric driven fire pumps be supplied with an automatic circulation relief valve. This valve is typically mounted on the neck of the discharge flange, before the discharge check valve. Circulation relief valves prevent the pump from overheating when operating at shutoff condition (no flow). The relief valve should be 3/4″ for flows not exceeding 2500 GPM and 1″ for pump with a rated capacity of 3000 to 5000 GPM. This valve should be inspected during your weekly test and should discharge to drain. Visual verification of the valve’s operation is critical; if the valve fails to operate, your fire pump will overheat in a very short period of time, as illustrated below.

NFPA 20, 2003 Edition section requires that the circulation relief valve be listed for fire pump service.

Overheating damage resulting from circulation relief valve failure
Overheating damage resulting from circulation relief valve failure

Bypass Loops:

NFPA 20 section requires that on applications where the suction supply is of sufficient pressure to be of material value to the system without the pump, the system shall include a bypass. This would allow you to do maintenance on the pump and still have some pressure available for your system. This will not give you 100 PSI at the furthest hose connection, but would afford some level of protection for the property.

bypass open

The pump suction, discharge, and bypass valves should be checked weekly to verify that they are fully open.

A weekly test should be conducted at no flow (shut off) condition. If the fire pump is an electric unit, test for 10 minutes. A diesel unit must be tested for 30 minutes every seven days. The Automatic Weekly test timer can be used for the test, but qualified personnel must be in attendance.

The annual test must be conducted at minimum, rated, and peak load. You must place a demand on the suction supply every third year; this requires a test via hose streams or via a flow meter loop to drain or to the reservoir. You can use a flowmeter loop piped to the pump suction (closed-loop metering) in the off years. The annual test data should be compared to the acceptance test and the certified factory test curve.

Sample certified factory performance test curve

Sample certified factory performance test curve

Degradation in excess of 5% of the pressure to the initial unadjusted acceptance test curve shall require an investigation to reveal the cause of degraded performance.
Pressure gauge accuracy should be checked annually
(change or recalibrate when 5% out of calibration).

A preventive maintenance program shall be implemented on all components and records shall be maintained on all work performed. Typically, the manufacturer’s recommendations should be followed, but NFPA 25 table 8.5.3 can be used as substitute requirements.

The importance of proper bearing lubrication cannot be overstated. It is difficult to judge how often a bearing should be greased. Many factors will influence the schedule, including the conditions of operation. A good “rule of thumb” is to add an ounce of grease every 3-6 months. NFPA 25 table 8.5.3 recommends an annual lubrication of the bearings. Make sure to avoid adding too much grease.

A preventative maintenance program must be established on the components of the pump assembly. The manufacturer’s recommendations must be followed. NFPA 25 requires that records shall be maintained on all work performed on the pump, driver, controller, and auxiliary equipment.

Stationary pumps dedicated for fire protection service save lives and protect property. They have proven to be very reliable, provided that they are inspected, maintained, and tested in accordance with the requirements of NFPA 25.

Inspection Testing Maintenance

How to Maintain a Water-Based Fire Protection System

By Michael Swahn P.E., MBA, President, Sebench

Engineering Fire protection equipment is a major investment for any facility. When functioning properly, it can save lives, reduce damage to property, limit the interruption of business, and lower insurance costs. A fire protection system that is not properly maintained is a fire protection system with reduced overall effectiveness, and it may even be useless. Seventy-seven percent of sprinkler system failures are due to the systems being shut off or not maintained. These figures should not raise doubts about the reliability of sprinklers; sprinklers have been found to be effective in fighting 96% of fires.* * (Fire Journal, July 1970; “An Analysis of Automatic Sprinkler System Reliability Using Current Data,” by John R. Hall Jr. PhD., NFPA, February 2, 2006.)

Standards and Guidelines — NFPA 25 The National Fire Protection Agency (NFPA) provides guidelines and standards regarding inspection, testing, and maintenance of wet-pipe sprinkler systems, dry-pipe sprinkler systems, fire pumps, and water storage tanks. The NFPA understands the importance of maintaining fire protection systems — it dedicated an entire standard solely to this issue — Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems (NFPA 25). Unfortunately, like most fire codes, it was written by engineers for engineers, making it difficult to be read and understood by everyone. NFPA 25 is part of the 2003 and 2006 International Building Code, and has been adopted into law in 46 states. Only Hawaii, Massachusetts, Mississippi, and Missouri have not yet adopted NFPA 25. The law requires that any change, even one as simple as adding another row of storage racks or rearranging office space, requires a qualified contractor, consultant, or engineer to evaluate the adequacy of the sprinkler system. You should always contact local and state building commissions for verification of what standards are adopted by a particular municipality or county, and use a reputable loss control engineer to ensure optimal protection.

Maintenance — When, How, and by Whom NFPA 25 specifies a range of inspection and maintenance activities that require various levels of expertise. Facility management is ultimately responsible for ensuring that all fire protection equipment is being properly maintained. The experience level of the employees at a facility will dictate what activities can be done “in house” and what activities must be left to a qualified contractor. See the table on the opposite page of when, how, and by whom specific activities should be tested.

Fire Pumps There are two types of fire pumps — horizontal and vertical. Most often, a pump is powered by a diesel engine. The water used in a water-based fire protection system is stored in a storage tank. These components have to be properly maintained on a regular basis to ensure optimal fire protection.

Horizontal Fire Pump Before a horizontal fire pump is operated, the following should be verified:

  1. Check the drip pockets under the packing glands for proper drainage.
  2. Check the packing adjustment — approximately one drip per second is necessary to keep packing lubricated.
  3. Observe the suction and discharge gauges. Readings greater than the suction pressure indicate leakage back from the system pressure through either the fire pump or jockey pump check valves. For a horizontal fire pump, the following should be verified on a weekly basis:

Reprinted from FPC/Fire Protection Contractor | | December 2008 edition

  1. Read the suction and discharge gauges. The difference between these readings indicates the churn pressure, which should match the rated pressure. The rated pressure can be found on the fire pump nameplate.
  2. Observe the packing glands for proper leakage for cooling the packing.
  3. Observe the discharge from the casing relief valve on the electric pumps and from the cooling water discharge line on the diesel pumps — adequate flow prevents overheating of the pump case.

Vertical Fire Pump For a vertical fire pump, the following should be verified on a weekly basis:

  1. Read the discharge gauge. The gauge pressure plus a lift factor should equal the rated pressure on the fire pump nameplate. To calculate the lift factor, multiply the distance (in feet) between the water level and the fire pump by 0.43. (For example, if the churn pressure on the nameplate is 50 psi and the pump is 10 feet above the water line, then the gauge should read 50 psi minus 4.3 psi, or 45.7 psi.)
  2. Observe the packing gland for proper leakage for cooling the packing.
  3. Observe the discharge from the casing relief valve on the electric pumps and from the cooling water discharge line on the diesel pumps — adequate flow prevents overheating of the pump case. An annual flow test of each pump assembly should be conducted by a reputable contractor. The contractor should test at the minimum, rated, and peak flow rates by controlling the quantity of water discharged through approved test devices.

Diesel Engine To ensure that the diesel engine powering a fire protection system is operating in a reliable and optimal way, you should do the following:

  1. Observe the discharge of the cooling water from the heat exchanger — if not adequate to prevent the engine from overheating, check the strainer in the cooling system for obstructions. If still inadequate, adjust the pressure-reducing valve for the correct flow.
  2. Check the engine instrument panel for the correct speed, oil pressure, water temperature, and ammeter-charging rate.
  3. Check the battery terminal connections for corrosion and clean them, if necessary.
  4. After ensuring that the pump has stopped running, check the intake screens, if provided. Also, change the diesel system pressure recorder chart.

Sprinkler System A sprinkler system is dependent on water. A water storage tank is a crucial part of the system; it needs regular maintenance and inspections in order to ensure proper fire protection. The water storage tank needs to be inspected daily in cold weather to ensure that it does not drop below 40°F. If the water temperature is continuously monitored, the frequency may be reduced to once a week. The water level and the condition of the water in the tank should be visually inspected monthly. If the water level is continuously monitored, the frequency may be reduced to once a quarter. The exterior of the tank should also be visually inspected quarterly. In addition, the interior of the tank should be inspected by a qualified contractor every three years for signs of rusting, corrosion, and the collection of debris. If corrosion protection is provided inside the tank, the frequency may be reduced to once every five years. If a control valve is sealed, it should be inspected weekly. If the valve is locked or has a tamper switch, the inspection frequency may be reduced to once a month. The valve inspection should verify that the valves are in the following condition: Control Valves — Inspect Weekly or Monthly

  1. In the normal open or closed position.
  2. Properly sealed, locked, or supervised.
  3. Accessible.
  4. Provided with appropriate wrenches.
  5. Free from external leaks.
  6. Provided with appropriate signs, such as “Sprinkler System No. 1” or “Divisional Valve No.1.”

Fire Department Connection — Inspect Weekly or Monthly

  1. The fire department connections are visible and accessible.
  2. Couplings or swivels are not damaged and rotate smoothly.
  3. Plugs or caps are in place and undamaged.
  4. Gaskets are in place and in good condition.
  5. Identification signs are in place.
  6. The check valve is not leaking.
  7. The automatic drain valve is in place and operating properly.

Waterflow Alarms — Inspect; Quarterly or Semiannually Test the waterflow alarms for each sprinkler system quarterly or semiannually using the inspector’s test connection (quarterly for pressure-type switches and semiannually for vane-type switches). The inspector’s test connection simulates the activation of the most remote sprinkler. The automatic fire alarm system should activate within 90 seconds after the inspector’s test connection is fully open. Verify that all the alarms transmitted off the premises were received by the alarm monitoring company.

Main Drain — Inspect Quarterly or Annually A main drain test should be conducted quarterly or annually, and any time the control valve has been closed, to determine whether there has been a change in the condition of the water supply piping and control valves. The static and flowing (residual) water pressures should be recorded and compared with the previous test results to determine if an obstruction exists. Control Valves — Inspect Annually Each control valve should be operated annually through its full range and returned to its normal position. Post indicator valves should be opened until spring or torsion is felt in the rod; this indicates that the rod has not detached from the valve. Post indicating and outside screw and yoke valves should be backed off a one-quarter turn from the fully open position to prevent jamming. Pressure Gauges — Inspect every five years: replace or calibrate all gauges every five years.

Reprinted from FPC/Fire Protection Contractor | | December 2008 edition When sprinklers reach the age of 50, a sample set of sprinklers should be submitted to a nationally recognized laboratory for testing to ensure they are in good working condition. A representative sample set of sprinklers should consist of a minimum of four sprinklers, or 1% of the total number of sprinklers per individual sprinkler sample, whichever is greater. If one sprinkler within a representative sample set fails to satisfy the test requirements, all the sprinklers represented by that sample shall be replaced. For fast-response sprinklers, testing should be conducted after 20 years of age. Thereafter, the sprinklers must be tested every 10 years (i.e. years 20, 30, 40, etc.)

Dry-Pipe Sprinkler Systems Enclosure — Inspect daily during cold weather. Enclosures that are designed to prevent a sprinkler riser from freezing should be inspected daily during cold weather conditions to ensure integrity, and to make sure the enclosure temperature remains above 40°F.

Priming Level — Inspect Quarterly High priming-water levels can affect the operation of supervisory air or nitrogen pressure maintenance devices. Test the water level as follows:

  1. Open the priming-level test valve. If water flows, drain it.
  2. Close the valve when the water stops flowing and air discharges. If air discharges when the valve is opened, the priming-water level could be too low. To add priming water, refer to the manufacturer’s instructions.

Quick-Opening Device — Inspect Quarterly

  1. Close the system control valve. 2. Open the main drain valve and keep it in the open position.
  2. Verify that the quick-opening device control valve is open.
  3. Open the inspector’s test valve. A burst of air from the device indicates that it has tripped.
  4. Close the device’s control valve. 6. Return the device to service in accordance with the manufacturer’s instructions and return the system to service.

Low-Point Drains — Inspect Annually Low-point drains are provided to collect the condensate inside the sprinkler piping. Each year, before the onset of freezing weather, all low-point drains should be drained to ensure that there is no condensate that can freeze and damage the sprinkler piping.

Dry-Pipe Valves — Inspect Annually Dry-pipe valves should be trip tested on an annual basis in warm weather with the control valve only partially open.

Dry-Pipe Valves — Full-Flow Test Every 3 Years A full-flow trip test generally requires at least two individuals: one of whom is stationed at the dry-pipe valve, while the other is at the inspector’s test connection valve. If possible, they should be in communication with each other. A full-flow trip test is conducted in the following manner:

  1. Open the main drain valve fully to clean any accumulated scale or foreign material from the supply water piping.
  2. Close the main drain valve.
  3. Record the system air or nitrogen, and the supply water pressures.
  4. Relieve the system air or nitrogen pressure by opening the inspector’s test connection valve completely. Concurrent with opening the valve, both the testers start their stopwatches. If two-way communication is not available, the tester at the dry valve must respond to the start of the downward movement on the air-pressure gauge.
  5. The tester at the dry-pipe valve records the air pressure at which the valve trips, and records the tripping time.
  6. The tester at the inspector’s test connection valve records the time at which water flows steadily from the test connection. This time is recorded for comparison purposes with previous tests and is not meant to be a specific pass/fail criterion. Note that NFPA 13, the Standard for the Installation of Sprinkler Systems, does not require water delivery to occur within 60 seconds in all cases.
  7. When clean water flows, the test is terminated by closing the system control valve.
  8. The air or nitrogen pressure and the time elapsed are to be recorded as follows: (a) from the complete opening of the inspector’s test connection valve to the tripping of the valve and (b) from the complete opening of the inspector’s test connection valve to the start of steady flow from the inspector’s test connection.
  9. Open all low-point drains; close when water ceases to flow. 10. Reset the dry-pipe valve and quick-opening device (if provided) in accordance with the manufacturer’s instructions and the system is returned to service.

Conclusion — Fire Protection Experts Maintaining fire protection equipment requires expertise and experience. When functioning properly, a properly maintained fire protection system can save lives and property from devastating loss.

About the Author: Michael Swahn P.E., MBA, is President of Sebench Engineering. Sebench experts are available to conduct a training class at your facility on how to maintain your fire protection equipment. For more information contact: Sebench Engineering, 2167 Eldorado Drive, Atlanta, GA 30345; (678) 222-0551, E-mail:, Website:
Reprinted from FPC/Fire Protection Contractor | | December 2008 edition

Equipment Testing Frequency

Fire Protection Component Activity


Level of Difficulty

Fire Pumps and Water Storage Tanks

Fire pump test



Fire pump test



Water Storage Tank Inspection Water storage tank inspection Water storage tank inspection

Weekly Monthly Every 5 years

Low Low High

Sprinkler Systems

Control valves inspection

Fire department connections inspection

Waterflow alarms test Main drain Flow test Control valves maintenance Flushing piping test

Pressure gauge calibration test

Weekly/monthly Quarterly Quarterly Annually Annually

Every 5 years

Low Low Low Low Low High

or replacement Every 5 years Medium

Sprinklers test Every 50 years High

Dry-Pipe Systems

Enclosure (cold weather) inspection

Daily/cold weather


Priming level (Dry-pipe valve) inspected



Quick-opening devices test



Low-point drains test

Annually – fall


Dry-pipe valves trip test

Annually – spring


Dry-pipe valves full flow trip

Every 3 years – spring


Importance of Sprinkler Testing

The Importance of Sprinkler System Main Drain Testing

Impairment to a Sprinkler System Can Have Catastrophic Consequences

By Neil P. Wu, FPE, CBO

Introduction: Degradation of the water supply or impairment to a sprinkler system can have catastrophic consequences. Periodic inspection, testing, and maintenance (ITM) of the sprinkler system is an essential, often mandated, and expected preventive measure to promote proper operation of a sprinkler system. Performing improper ITM can result in undue risk to the contractor if improper testing and/or maintenance are found to contribute to fire damages caused by an underperforming sprinkler system. Good engineering practices are discussed for the evaluation of water supplies through main drain testing for automatic, wet-pipe, water-based fire sprinkler systems. Background Much of a sprinkler system’s overall performance relative to controlling the fire is dictated by the available water supply, assuming that the proper design was applied to the hazard being protected. The basic principle of a hydraulically designed water-based fire sprinkler system is that the peak flow and pressure demand is no greater than the available supply. If an in adequate flow and/or system pressure is delivered, the sprinkler system is likely to operate improperly, possibly allowing the fire to spread out of control.

The hydraulic demand at a system reference point, such as the base of riser (BOR), can be graphically compared to the available supply to determine the adequacy of the water supply. A hypothetical system demand is shown in Figure 1 where the system demand point is less than the supply curve (plotted as a line on semi-log graph).

The design margin or “buffer” is the pressure difference in the available supply curve and the system hydraulic demand point, in psi. The model codes governing the design of automatic sprinkler systems are silent regarding the minimum design buffer, leaving the size of the margin to the discretion of the designer. The buffer should account for foreseeable variations in water system strength such as seasonal effects and peak water consumption hours.


Water Supply Evaluation

Accurately characterizing the flow and pressure of the available water supply is paramount not only during the initial design and installation of a fire sprinkler system, but also for the continued protection of the building. The following actions are provided for consideration for the ITM of water-based wet pipe fire sprinkler systems:

1. Perform Periodic Testing of the Fire Sprinkler System

— NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, is a reference commonly adopted for enforcement and offers a schedule of preventive ITM activities. In particular, with respect to water supply, Section 13.2.5 of NFPA 25 states that a main drain test shall be conducted annually at each water-based fire protection system riser to determine whether there has been a change in the condition of the water supply, supply piping, and control valves. Although it is customary to consider the main drain test as an “annual” event, more frequent tests are required depending on the water supply configuration. The frequency of the main drain test is increased to a quarterly basis where the sole source of the water supply is through a backflow preventer and/or pressure reducing valves. Verify these tests are being conducted on a timely basis in accordance with NFPA 25 or other applicable requirements. Written records should be kept for future reference and troubleshooting.

2. Conduct an Initial Water Distribution System Analysis

— A key fundamental to using the main drain test data to monitor changes in the water supply assumes that the water supply was adequate at the time of original installation of the system. Performing a water distribution system flow test (i.e., hydrant flow test) at the initial acceptance testing for comparison to the sprinkler system design is often overlooked and not validated during the building construction inspection process. Original data obtained well in advance of construction may not accurately describe the water supply strength when construction is complete, and more importantly, at the time of building occupancy.

Although a main drain test may repeatedly produce similar residual pressures at regular inspections, the system supply may have been inadequate from inception. Without calibration of the actual water distribution supply curve to the sprinkler system design criteria, an inadequate water supply can remain undetected despite performing the required main drain tests.

NFPA 291, Recommended Practice for Fire Flow Testing and Marking of Hydrants, is a recommended practice that addresses hydrant flow tests. For new building construction, a hydrant flow test should be performed at the time of initial acceptance testing for the sprinkler system, just prior to building occupancy. For an existing system in service, a water supply flow test should be performed at the next inspection interval, if the baseline test was not performed and recorded at the completion of construction. The water supply curve can be used to validate the design flow data used by the design professional and/or installing fire sprinkler contractor and for calibration of the main drain test residual pressures. If the as-built data does not agree with the design flow test figures and/or the supply is inadequate to satisfy the sprinkler system demand, investigation of the water supply should occur immediately.

After the water supply curve is characterized and determined to satisfy the sprinkler system demand, future main drain tests results can be checked against the baseline value to confirm water supply adequacy. With this foundation established, the results of the main drain test can be used with confidence.

3. Test and Calibrate Pressure Gauges — The data obtained from sprinkler system testing is only as valid as the instruments used for measurement. Relying on faulty pressure gauges can produce inaccurate test results. Contractors performing ITM services should inspect and test pressure gauges periodically to verify proper operation. Based on NFPA 25, Section 12.2.8, pressure gauges are to be inspected on a monthly basis and replaced with a calibrated gauge or tested every five years to be within 3% of the full scale in comparison with a calibrated gauge. A system for identifying components and the date of replacement or calibration (e.g., affixing unique identification numbers and dates) should be incorporated. Written records should identify the specific gauges replaced or tested. Use of properly calibrated gauges can prevent the collection of misleading test data.

4. Investigate Reductions in Main Drain Residual Pressures — The 2008 edition of NFPA 25 includes a new provision that states where a 10% reduction in the full flow pressure is observed from previous results, the cause of the reduction shall be identified and corrected. However, good engineering practices dictate that any reduction in the residual pressure observed during a sprinkler system flow test should be investigated. A decrease in residual pressure is a possible indicator of a deteriorated water supply, obstruction, closed valve, or other system impairment.

At a minimum, the investigation of the reduced residual pressure should consist of an impact analysis to determine the effect on the sprinkler system hydraulic demand.

The pressure buffer of a sprinkler system can vary depending on the system designer’s anticipation of nominal consumption, future demand, infrastructure improvements, seasonal pressure changes, etc. Minor changes in the observed main drain test residual pressure can swing the demand/supply relationship into a deficit, resulting in an inadequate water supply. When conducting a main drain test, observation of a drop in residual pressure from a previous result is a qualitative indicator of diminished water supply strength. Investigation of any drop in main drain test residual pressure should occur prior to the 10% threshold, since this prescriptive requirement does not account for systems that have smaller design cushions that can be overcome by slight decreases in residual pressure. The main drain test can be used to detect a weakening water supply, but the impact on the sprinkler system is best determined by conducting a hydrant flow test.

5. Establish a Management of Change Protocol — A protocol should be developed in collaboration with the property owner to identify changes, determine the impact, and if necessary, remedy the deficiency. In the event a sprinkler system is impaired, administrative procedures for notification and mitigation are presented in NFPA 25, Chapter 14, and should be included in the protocol.

The protocol should include systematic investigation procedures for use when a reduction in the water supply is detected. A hydrant flow test upstream of the sprinkler system may serve as a starting point to determine the cause of the pressure reduction. If the water distribution system is found to be adequate, the cause of the reduction is likely to be found between the point of connection (POC) to the water utility and the sprinkler system riser. System components from the POC, including control valves, backflow preventers, and pressure-reducing valves, should be inspected and tested for proper operation. Additional direction is  provided by NFPA 25, Chapter 13, for investigating fire protection system piping for possible sources of materials that can cause blockage. After repairs are made, the sprinkler system should be restored and tested to verify hydraulic performance is satisfactory.


The successful operation of a fire sprinkler system relies heavily on the characteristics of the available water supply. An inadequate water supply can cause improper operation during a fire event leading to unnecessary fire damage. Internationally recognized fire standards are available as best engineering practices for ITM of fire protection systems. Implementing the features of these standards will reduce the potential for an inadequate sprinkler system water supply to remain undiscovered.

About the Author:

Mr. Neil P. Wu, P.E., CBO is a licensed Fire Protection Engineer, a Certified Fire and Explosion Investigator, a Certified Building Official, and a Managing Engineer at Exponent, Inc., a scientific and engineering consulting firm.

He may be reached at: Exponent, Inc., 17000 Science Drive, Suite 200, Bowie, MD 20715; E-mail:, Website:


Scroll to Top