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Sprinkler Types and Inspection Schedules

Sprinkler Types and Inspection Schedules

Wet – Wet type systems are the most common type of sprinkler system that is installed. A wet pipe system has water in the pipes in the ambient or normal condition and has heat responsive elements on all sprinklers. Thus, water is instantaneously discharged from a sprinkler when it actuates.

Dry – In areas where low temperatures could cause a wet pipe system to freeze, a dry pipe system is intended for use. Dry pipe systems are pressurized with air in the ambient condition and experience an inherent delay in the discharge of water to allow the pressurized air in the system to escape. When a sprinkler actuates, air is released through the sprinkler, allowing water to flow into the piping system through the dry pipe valve. NFPA 13 mandates that the time for the water to reach the most remote sprinkler be no longer than 60 seconds. This time delay allows the fire to grow larger than it would with a wet pipe system of similar design, and the larger fire size results in more sprinklers in the fire area actuating.

To limit the size of dry pipe systems, a volumetric limitation with a maximum capacity of 750 gallons is placed on dry pipe systems. A quick opening device, such as an accelerator or an exhauster, is installed to rapidly remove air from the system and speed the operation of the dry pipe valve and is required when the system volumetric capacity exceeds 500 gallons.

Preaction and Deluge – Preaction systems and deluge systems required fire detectors (smoke, heat, etc.) for the actuation of the system. A deluge system uses open sprinklers or nozzles, so that all flow water is discharged when the deluge valve actuates. Deluge systems can be used for occupancies where the hazard is considered severe, such as with flammable liquid hazards where the fire could spread over a large floor area.

Preaction system have closed heads and pipes filled with pressurized air that supervise a piping system, and can be considered for the protection of valuable assets or irreplaceable property. The detection system for a preaction system can be designed to prevent water discharge in cases of a false alarm from the detection system, or in case of a sprinkler whose element has encountered mechanical damage.

The detection system on a preaction system can be designed with a preaction logic capable of meeting one of the following objectives:

-Actuation of a fire detector trips a deluge valve to admit water into the sprinkler piping to await the actuation of a sprinkler.

-Actuation of a fire detector or actuation of a heat-responsive element on a sprinkler trips a deluge valve to admit water into the sprinkler piping.

-Actuation of a fire detector and actuation of a heat-responsive element on a sprinkler trips a deluge valve to admit water into the sprinkler piping.

Sprinkler Head Types

Spray sprinklers are manufactured in three basic styles. A standard spray upright (SSU) sprinkler is mounted on upright above a branch line pipe, usually in a room with exposed structural elements, and has a deflector, a metal plate whose edge is distinctively bent to deflect water downward from the sprinkler. A standard spray pendant (SSP) sprinkler is mounted below the branch line, usually mounted at or below the surface of a suspended ceiling and is characterized by a flat deflector. SSU and SSP discharge patterns are designed to be the same. Sidewall sprinklers have a specifically designed deflector that allows the sprinkler to discharge water from a wall-mounted position.

Variations on upright, pendant, and sidewall sprinkler are the dry upright, dry pendant, and dry sidewall sprinklers. These special sprinklers are manufactured with a seal at the inlet that prevents water from entering the nipple until the sprinkler actuates. These sprinklers can be extended from a wet pipe system into an unheated area, such as a walk-in freezer, an outside loading dock, or an unheated attic space, or can be used in the pendant position on a dry pipe system to prevent condensation from entering the sprinkler and freezing.

Pendant Head Upright Head Sidewall head Concealed Head

Dry Pendant Head

Sprinkler Head Temperature Ratings

Max Ceiling Temperature (F)

Head Temperature Rating (F)

Temperature Classification

Color Code

Glass Bulb Color

100

135-170

Ordinary

Uncolored or Black

Orange or Red

150

175-225

Intermediate

White

Yellow or Green

225

250-300

High

Blue

Blue

300

325-375

Extra High

Red

Purple

375

400-475

Very Extra High

Green

Black

475

500-575

Ultra High

Orange

Black

625

650

Ultra High

Orange

Black

Sprinkler Coverage

Another development in sprinkler manufacturing is the extended coverage sprinkler. The deflectors on these sprinklers are designed to discharge water over larger areas than standard sprinklers. While this means that each sprinkler must have a higher flow, it results in increased allowable distance between sprinklers, with the possibility that fewer sprinklers may be required in a compartment given size.

Sprinkler Responses

A major development in sprinkler technology was the quick response sprinkler, a sprinkler with a specially designed response element that allows the rapid transfer of heat to the heat-responsive element and provides a more expeditious delivery of water to the fire. At the time of sprinkler actuation, the fire should be smaller with a quick response sprinkler than with a standard response sprinkler, resulting in fewer sprinklers likely to actuate. Sprinkler elements are either glass bulbs or eutectic (soldered) elements.

The response of quick response and standard response sprinklers can be modeled by designers to estimate the time for a sprinkler to actuate, given ceiling height, fire size, and response time index (RTI), using the DETACT computer program, developed by the Building and Fire Research Laboratory at the National Institute of Standards and Technology (NIST). Response time index is a measure of the sensitivity of a sprinkler heat responsive element, with low RTI values being very sensitive to actuation by heat, and high RTI values being less sensitive.

Sprinkler for Storage Applications

ESFR and large Drop sprinklers are for specialized high challenge fire hazards. An ESFR sprinkler has a quick response element and an extra large orifice that allows for greater amounts of water to be applied early in the fire development, usually on a high challenge fire. Large drop sprinklers have large deflectors with widely spaced teeth to facilitate the creation of large water drops intended to penetrate a high velocity fire plume without evaporating, resulting in some water reaching the burning materials. The fire plume is the column of smoke and gas traveling upward from a fire.

Sprinkler System Inspection Requirements

NFPA requires that certain activities be performed at prescribed frequencies. However, rarely does an inspection and test agreement assign all of these activities and frequencies to a fire prevention company. To comply fully, an implied partnership is formed between the owner or the ownerʼs representative and the contractor. All of the requirements of NFPA 25 are the responsibility of the owner, and the contractor relies on the owner to perform all inspections and tests not specified in the agreement.

A common agreement for a wet sprinkler system will have the fire protection contractor coming to the building on an annual basis to conduct the annual inspections (See Below), while the owner or ownerʼs representative performs the quarterly, monthly, and weekly required inspections.

Unless specifically referenced in the agreement all other less-frequent activities are not included such as testing gauges every 5 years, testing sprinklers every 5, 10, 20, or 50 years; and internally inspecting alarm valve, check valves, strainers, filters, and orifices. These activities are normally performed by the fire protection contractor but are invoiced as additional periodic services.

Sprinkler System Inspection Frequencies

Device

Activity

Frequency

Sprinkler System

Gauges (Dry, Pre-Action, Deluge Systems)

Inspection

Weekly/Monthly

Control Valves

Inspection

Weekly/Monthly

Alarm Devices

Inspection

Quarterly

Gauges (Wet Pipe Systems)

Inspection

Monthly

Hydraulic Nameplate

Inspection

Quarterly

Buildings

Inspection

Annually (prior to freezing)

Hanger/Seismic Bracing

Inspection

Annually

Pipe and Fittings

Inspection

Annually

Sprinklers

Inspection

Annually

Spare Sprinklers

Inspection

Annually

Fire Department Connections

Inspection

Quarterly

Alarm Devices

Test

Quarterly/Semi-Annually

Main Drain

Test

Annually

Anti-freeze Solution

Test

Annually

Gauges

Test

5 years

Sprinklers — Extra High Temperature

Test

5 years

Sprinklers — Fast Response

Test

At 20 years and every 10 thereafter

Sprinklers

Test

At 50 years and every 10 thereafter

Valves

Maintenance

Annually or as needed

Obstruction

Maintenance

5 years or as needed

Low Point Drains (Dry Pipe Systems)

Maintenance

Annually prior to freezing and as needed

Private Fire Service Main

Hose Houses I

nspection

Quarterly

Hydrants (Dry Barrel with Wall) I

nspection

Annually and after each operation

Monitor Nozzle I

nspection

Semi-Annually

Hydrants (Wet Barrel) I

nspection

Annually and after each operation

Mainline Strainers I

nspection

Annually and after each significant flow

Piping (Exposed) I

nspection

Annually

Piping (Underground) I

nspection

See NFPA 25

Monitor Nozzle

Test

Flow Annually (Range and Operation)

Hydrants

Test

Flow Annually

Piping (Exposed and Underground)

Flow Test

5 years

Mainline Strainers

Maintenance

Annually and after each operation

Hose Houses

Maintenance

Annually

Hydrants

Maintenance

Annually

Monitor Nozzle

Maintenance

Annually

Standpipe

Control Valves I

nspection

Weekly/Monthly

Pressure Regulating Devices I

nspection

Quarterly

Piping I

nspection

Quarterly

Hose Connections I

nspection

Quarterly

Cabinet I

nspection

Annually

Hose I

nspection

Annually

Hose Storage Device I

nspection

Annually

Alarm Device

Test

Quarterly

Hose Nozzle

Test

Annually

Hose Storage Device

Test

Annually

Hose

Test

5 years/3 years

Pressure Control Valve

Test

5 years

Pressure Reducing Valve

Test

5 years

Hydrostatic Test

Test

5 years

Flow Test

Test

5 years

Main Drain Test

Test

Annually

Hose Connections

Maintenance

Annually

Valves

Maintenance

Annually or as needed

Water Storage Tanks

Conditions of Water in Tank

Inspection

Monthly/Quarterly

Water Temperature

Inspection

Daily/Weekly

Heating System

Inspection

Daily/Weekly

Control Valves

Inspection

Weekly/Monthly

Water Level

Inspection

Monthly/Quarterly

Air Pressure

Inspection

Quarterly

Tank Exterior

Inspection

Quarterly

Support Structure

Inspection

Quarterly

Catwalks and Ladders

Inspection

Quarterly

Surrounding Areas

Inspection

Annually

Valves

Control Valves

Sealed

Inspection

Weekly

Locked

Inspection

Monthly

Tamper Switches

Inspection

Monthly

Alarm Valves

Exterior

Inspection

Monthly

Interior

Inspection

5 years

Strainers, filters, orifices

Inspection

5 years

Check Valves

Interior

Inspection

5 years

Pre-Action/Deluge Valves

Enclosure (cold)

Inspection

Daily/Weekly

Exterior

Inspection

Monthly

Interior

Inspection

Annually/5 years

Strainers, Filters, Orifices

Inspection

5 years

Dry Pipe Valves/Quick Opening Devices

Enclosure

Inspection

Daily/Weekly

Exterior

Inspection

Monthly

Interior

Inspection

Annually

Strainers, Filters, Orifices

Inspection

5 years

Pressure Reducing and Relief Valves

Sprinker System

Inspection

5 years

Hose Connections

Inspection

Quarterly

Hose Racks

Inspection

Quarterly

Fire Pump

Inspection

Weekly

Backflow Prevention Assemblies

Reduced Pressure

Inspection

Weekly/Monthly

Reduced Pressure Detectors

Inspection

Weekly/Monthly

System Devices

Fire Department Connections

Inspection

Quarterly

Main Drains

Test

Annually/Quarterly

Water-Flow Alarms

Test

Quarterly

Control Valves

Position

Test

Annually

Operation

Test

Annually

Supervisory

Test

Semi-Annually

Pre-Action/Deluge Valves

Priming Water

Test

Quarterly

Low Air Pressure Alarm

Test

Quarterly

Full Flow

Test

Annually

Pre-Action/Deluge Valves

Priming Water

Test

Quarterly

Low Air Pressure Alarm

Test

Quarterly

Full Flow

Test

Annually

Dry Pipe Valves/Quick Opening Devices

Priming Water

Test

Quarterly

Low Air Pressure Alarm

Test

Quarterly

Quick Opening Devices

Test

Quarterly

Trip Test

Test

Annually

Full Flow Trip Test

Test

3 years

Pressure Reducing and Relief Valves

Sprinkler System

Test

5 years

Circulation Relief

Test

Annually

Pressure Relief Valves

Test

Annually

Hose Connections

Test

5 years

Hose Racks

Test

Annually

System Devices

Backflow Prevention Assemblies

Maintenance

Annually

Control Valves

Maintenance

Annually

Pre-Action/Deluge Valves

Maintenance

Annually

Dry Pipe Valves/Quick Opening Devices

Maintenance

Annually

Building Ownerʼs Responsibility

As you know, testing and inspection of fire protection systems and devices is the responsibility of the building owner. NFPA 25 1998 Edition section 1-4.2 states “the responsibility for properly maintaining a water-based fire protection system shall be that of the owner(s) of the property. By means of periodic inspections, tests, and maintenance, the equipment shall be shown to be in good operating condition, or any defects or impairments shall be revealed. Inspection, testing, and maintenance shall be implemented in accordance with procedures meeting or exceeding those established in this document [NFPA 25] and in accordance with the manufacturer’s instructions. These tasks shall be performed by personnel who have developed competence through training and experience.”

Any sprinkler system deficiency or performance related issue shall be repaired by the building owner. NFPA 25 1998 Edition section1-4.4 states that “the owner or occupant promptly shall correct or repair deficiencies, damaged parts, or impairments found while performing the inspection, test, and maintenance requirements of this standard. Corrections and repairs shall be performed by qualified maintenance personnel or a qualified contractor.”

Water Supply and Quality

Water supplies should be tested prior to sprinkler installation to reduce the likelihood of contamination from water source bacteria. Additionally, the quality of the water should be understood to reduce corrosion that is induced from highly alkaline or acidic water supplies. NFPA 13 1999 Edition states in section 9-1.5 that “in areas with water supplies known to have contributed to microbiologically influenced corrosion (MIC) of sprinkler system piping, water supplies shall be tested and appropriately treated prior to filling or testing of metallic piping systems.”

NFPA 13 1999 Edition section 10-2.1 states “Fire service mains (from water supply to system riser) and lead-in connections to system risers shall be completely flushed before connection is made to sprinkler piping. Water supplies should be flushed to ensure that pipe scale and debris is not introduced into the sprinkler system at the time of installation. The flushing operation shall be continued for a sufficient time to ensure thorough cleaning.”

General Fire Pump Information

Information provided from Fire Protection System Inspection, Testing, and Maintenance Third Edition Carson and Klinker

A fire pump is designed to increase the water pressure. The pump intake discharge piping must be capable of flowing the required volume to which the pump will add the needed pressure for fire protection. The pump can be started manually, but is usually arranged to start automatically upon a drop in system pressure or the activation of a fire suppression system. Automatic starting requires a controller. Engines for operating the pump can be electric or diesel. Sizes range from 25 gallons per minute (gpm) to 5000 gpm.

Fire pumps are needed whenever pressure requirements of a fire protection system exceed the capabilities of the available water supply. Two types of pumps are typically used: centrifugal fire pumps, where water is available to supply the pump under pressure, such as a city supply; and vertical turbine pumps, where the available water supply is in a static state, such as a pond or reservoir.

Water enters the centrifugal pump through the suction inlet and passes to the center of an impeller. Rotation of the impeller drives the water by centrifugal force to the rim, where it discharges. One of the unique features of a centrifugal pump is that it takes advantage of the inlet water pressure and adds the pump pressure to it. For example, a centrifugal pump with a rated pressure of 100 psi at a certain flow having a 25 psi inlet pressure will produce that flow at 125 psi.

A vertical turbine pump usually has a right-angle gear drive with impellers connected to the pump head by a vertical shaft. As the pump operates, the water is passed from one impeller to the next impeller, gaining additional pressure at each subsequent impeller until the water passes through the pump outlet. The number of impellers indicates the number of stages for the pump.

Fire pumps are rated by their ability to pump a specific volume of water, usually measured in gallons per minute or liters per minute at a rated pump pressure and pump speed. The pump must be able to deliver 150% of this rated flow at 65% of its rated pressure. In addition, under no-flow conditions, the pressure must reach not more than 140% of the rated pressure (sometimes called the churn pressure). Most centrifugal pumps have a single impeller and are known as single-stage pumps. For high pressure demands, multistage pumps are needed.

Pumps are started and stopped by controllers. They start the pump when they sense the need for additional pressure or upon activation of a fire-extinguishing system. The controller can be arranged to stop the pump after reaching both a preset pressure and preset time. Pumps have timers so they will not continuously start and quickly stop, as would happen for a small leak or small flow. For the same reason, a small low-volume pump, known as a jockey pump, is often installed in the piping parallel to the fire pump to prevent cycling of the fire pump due to leaks.

Pumps are provided with circulation relief valves, to discharge water when the pump is being run with no water discharge. This valve is provided because, without it, the temperature of the water trapped in the pump casing would increase due to the centrifugal force created by the pump. The higher temperature could damage the fire pump.

Pumps taking suction from ponds or wet pits are provided with screens to make sure that the pump is not damaged by the introduction of solid materials into the pump. Foot valves are also provided on suction lines to assure that the pump maintains its “prime.” (Centrifugal pumps need the inlet piping and the pump casing full of water in order to start pumping. This water is called the “priming water” or “prime”).

Where variable-speed drivers are used (e.g., engine-driven pumps), pressure-relief valves are required. The relief valve will open should pressures exceed the system design pressure due to engine overspeed. Pressure-relief valves are also needed when the pump discharge pressure can exceed the rated pressure of any piping or valves on the discharge side of the pump.

Fire Pump Testing and Maintenance Frequency

Per NFPA 25, 2002

Device

Activity

Frequency

Pump System

Lubricate pump bearings

Change

Annually

Check pump shaft end play

Check

Annually

Check accuracy of pressure gauges and sensor

Check

Annually

Check pump coupling alignment

Check

Annually

Wet pit suction screens

Check

After each operation

Mechanical Transmission

Lubricate coupling

Change

Annually

Lubricate right-angle gear drive

Change

Annually

Electrical System

Exercise isolating switch and circuit breaker

Test

Monthly

Trip circuit breaker (if provided)

Test

Annually

Operate manual starting means (electrical)

Test

Semi-annually

Inspect and operate emergency manual start

Test

Annually

Tighten electrical connections as necessary

Check

Annually

Lubricate mechanical moving parts

Check

Annually

Calibrate pressure switch settings

Check

Annually

Grease motor bearings

Change

Annually

Diesel Engine System

Fuel

Tank level

Check

Weekly

Tank float switch

Test

Weekly

Solenoids valve operation

Test

Weekly

Strainer, filter, or dirt leg, or combination thereof

Clean

Quarterly

Water and foreign material in tank

Clean

Annually

Water in system

Check/Clean

Weekly

Flexible hoses and connectors

Visual Inspection

Weekly

Tank vents and overflow piping unobstructed

Check

Annually

Piping

Visual Inspection

Annually

Lubrication System

Oil level

Check

Weekly

Oil change

Change

Annually

Oil filter

Change

Annually

Lube oil heater

Check

Weekly

Crankcase breather

Change/Clean

Quarterly

Cooling System

Level

Check

Weekly

Antifreeze protection level

Test

Semi-annually

Antifreeze

Change

Annually

Adequate cooling water to heat exchanger

Check

Weekly

Rod out heat exchanger

Clean

Annually

Water pump(s)

Visual Inspection

Weekly

Condition of flexible hoses and connections

Check

Weekly

Jacket water heater

Check

Weekly

Inspect duct work, clean louvers (combustion air)

Check/Change

Annually

Water strainer

Clean

Quarterly

Exhaust System

Leakage

Check

Weekly

Drain condensate trap

Check

Weekly

Insulation and fire hazards

Visual Inspection

Quarterly

Excessive back pressure

Test

Annually

Exhaust system hangers and supports

Visual Inspection

Annually

Flexible exhaust section

Visual Inspection

Semi-annually

Battery System

Electrolyte level

Check

Weekly

Terminals clean and tight

Check

Quarterly

Remove corrosion, case exterior clean and dry

Change

Monthly

Specific gravity or state of charge

Test

Monthly

Charger and charge rate

Visual Inspection

Monthly

Equalize charge

Check

Monthly

Electrical System

General inspection

Visual Inspection

Weekly

Tighten control and power wiring connections

Check

Annually

Wire chafing where subject to movement

Check

Quarterly

Operation of safeties and alarms

Check/Test

Semi-annually

Boxes, panels, and cabinets

Clean

Semi-annually

Circuit breakers or fuses

Check

Monthly

Circuit breakers or fuses

Change

Biennially

 

Backflow Prevention Devices

Double Check Valve Assembly (DC)

The double check valve assembly (DC) is composed of two single, independently acting check valves. The unit also has two tightly closing, resilient seated, shutoff valves located at each end of the device and four test cocks for the testing of the check valves.

Reduced Pressure Principal Assembly (RP)

Commonly referred to as an RP or RPP, this device consists of two independently acting check valves, together with an automatically operating pressure differential relief valve located between the two check valves. The first check valve reduces the supply pressure at a predetermined amount so that during normal flow, and at cessation of normal flow the pressure between the two check valves shall be lower than the supply pressure. If either check valve leaks, the relief valve will discharge to atmosphere. This will maintain the pressure in the zone between the two check valves lower than the supply pressure. The unit also has two, resilient seated, shutoff valves (one upstream and one downstream of the checks) and properly located test cocks for field testing.

Pressure Vacuum Breaker (PVB)

The pressure vacuum breaker (PVB) is a device that contains within a single body, a single loaded check valve and a loaded air opening valve which opens to admit air whenever the pressure within the body of the device approaches atmospheric.

The device has two tight closing, resilient seated, shut-off valves, and it is fitted with test cocks, appropriately placed, for testing the device.

Dual Check Valve (DuC)

The dual check (DuC) is a device which has two single, independent acting check valves in series. It does not have any test- cocks and is generally not field tested.

Dual Check with Atmospheric Port (DCAP)

This device has two independent acting check valves with a relief valve located between the checks. The device is not testable and should only be used for lower degrees of hazard.

Atmospheric Vacuum Breaker (AVB)

An atmospheric vacuum breaker (AVB) is a device which has a moving element inside, which during flow prevents water from spilling from the device and during cessation of flow, drops down to provide a vent opening. This device should not remain under pressure for long durations, and it cannot have any shutoff valve downstream of it.

Air Gap

An air gap is a physical separation between the free flowing discharge end of a potable pipe line and an open or non- pressure receiving vessel. To have an acceptable air gap, the end of the discharge pipe has to be at least twice the diameter of the pipe above the topmost rim of the receiving vessel, but in no case can this distance be less than one inch. This may seem to be the simplest, most effective and least expensive type of protection. However, the chance for future cross- connections the cost of additional pumps to pressurize the system often makes this an expensive protection system.

 

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