Automatic Sprinkler systems Design | Installation | Materials

This article is about Sprinkler system design criteria, General Notes, Specification, Materials Requirements, International Standards and codes for engineers, supervisors and technicians.

How Do Fire Sprinklers Works?

Fire sprinklers work because high heat triggers the sprinkler system. When a blaze ignites, the air directly above it heats rapidly. When the air is hot enough and reaches a sprinkler head, it triggers a chain reaction. Most sprinkler heads feature a glass bulb filled with a glycerin-based liquid.

Automatic Sprinkler systems Design | Installation | Materials

Automatic Sprinkler systems Design | Installation | Materials

Automatic Sprinkler systems Design | Installation | Materials

Buildings to be protected by Automatic Sprinkler systems.

a. The Contractor will design, fabricate, install and test the Automatic Sprinkler systems described in this specification. The work will start at a flange located approximately one foot above finished grade or slab level and will include complete and working automatic sprinkler systems covering the areas and equipment shown on the drawings.

b. All equipment, valves and other devices shall be U.L. listed and/or FM approved for use in Automatic Sprinkler systems. All work performed shall be in accordance with NFPA Standards 13, 231 and 231C and the attached specifications.

c. The equipment and services to be provided by the Contractor shall include, but not be limited to the following:

(i) Design services, including the preparation of detailed design and installation drawings, and hydraulic calculations. Detailed design and installation drawings together with hydraulic calculations shall be submitted for review and approval by the Owner, prior to the start of any fabrication or
construction. In addition, submittals shall include detailed catalog cut sheets for all components to be supplied including performance and dimensional data. Sprinkler head data submitted shall include type of sprinkler, design characteristics, temperature range, and type of material.

(ii) Provision of all materials and equipment required for the complete automatic sprinkler systems, included alarm check valves, isolation valves, sprinkler heads, gauges, pressure switches, pipe and fittings, steel supports and all other components required to supply a complete and functional system unless specifically excepted.

(iii) Shop fabrication of all piping, fittings, hangers and supports.
(iv) Delivery, unloading, storage and protection of all materials and equipment provided by the Contractor.
(v) All labor, standard and special tools, materials and equipment required for the construction, operation and testing of the automatic sprinkler systems.

(vi) Installation of all equipment and materials provided and required to form complete and functional automatic sprinkler systems.
(vii) Flushing and testing of completed systems.
(ix) One lot of any special tools required for the operation, maintenance and periodic testing of the automatic sprinkler systems.

d. The following equipment and services are outside of the scope of the Fire Protection Contractor:

(i) Installation, flushing and testing of the underground fire water loop with feed mains supplying the automatic sprinkler systems terminating at locations shown on the drawings.
(ii) Painting of all piping, fittings and equipment.
(iii) Installation of complete fire alarm system including control panels, power supply, conduit and wiring. The Fire and Gas Control Panel will receive signals from the pressure switches provided by the Contractor, indicating the operation of the sprinkler alarm valve.
(iv) All drawings required to show the buildings to be protected by automatic sprinkler systems, to show the layout of associated piping and to show the locations of interface connections between the sprinkler systems and the water supply system.
(v) Concrete footings and foundations and main structural steel, as shown on the drawings.


The successful contractor shall be properly experienced to plan, install, and maintain sprinkler systems. The Contractor shall have a representative of their company on staff full-time that has a minimum of five (5) years experience in designing automatic sprinkler systems for industrial facilities. This individual shall oversee, and/or design, and supervise the installation of the automatic sprinkler systems.

General Design Requirements for Sprinkler System

a. The automatic sprinkler systems for the buildings indicated on the drawings shall be designed in accordance with NFPA 13, this specification and all referenced documents to provide complete coverage of the buildings described below or shown on the fire protection plans. Systems shall be
hydraulically calculated to provide complete coverage of the areas to be protected at the rate specified below. 

Required densities and design area(s) are as follows:

b. System design shall be based on hydraulic calculations per NFPA-13 and NFPA-30. The required water supply for each system shall be calculated by the Contractor back to the supply pump discharge flange. The design shall incorporate only one pump running with the supply data to be used
from the fire water pump P& ID drawings.

c. A post indicator valve shall be provided by the Owner to serve as an isolation valve provided in the underground water supply line to each sprinkler system. This will allow isolation of any one system without impairing the water supply to the other systems. The alarm check valve shall be
installed immediately downstream of the system isolating valve.

d. Pressure gauges shall be provided in the alarm valve trim to indicate the water pressure immediately upstream and downstream of the alarm valve. The gauges shall be provided with an isolation valve for maintenance purposes.

e. A water flow pressure switch shall be provided in the alarm valve trim to initiate an alarm during a fire condition. This switch shall be provided with an isolation valve to allow maintenance to remove the device without affecting the system.

f. In order to minimize fluctuations on the supply side of the alarm valve a variable type trim with retard chamber shall be used.

g. Fire department connections shall be provided for all sprinkler systems connected to the system side of the alarm check valve. The Fire department connections shall include 2 1/2  in brass, siamese  hose connections, NH female threads, with brass chain and caps, and polished brass cover plate
marked “AUTO-SPKR”. All threads shall match the equipment used by the plant fire brigade.

h. All sprinkler systems shall be designed to drain back to the main drain valve where practical. Drain valve discharge shall be piped to the building exterior and terminate with a 90 degree elbow located approximately one foot above grade. Auxiliary drains shall be provided at all low points trapping water. Main drain valves and auxiliary valves shall be installed in accordance with NFPA 13.

i. An inspector’s test connection consisting of a 45 degree elbow, open sprinkler and control valve shall be provided for each system and installed in accordance with NFPA 13. The inspector’s test connection shall be installed at the furthest point from the alarm valve and located outside the
protected area a maximum of five feet above finished grade.

j. Each system shall be provided with a water motor gong installed in accordance with NFPA 13.

k. Hydraulically designed systems shall have a noncorrosive metallic hydraulic design data nameplate permanently attached to the riser, indicating the location and basis of design, including the discharge density, size of remote area, system demand, and the residual pressure required at the
base of the riser.

In addition to the hydraulic placard, stainless steel signs with appropriate identification and instructions shall be provided at each water motor gong, each inspector’s test connection, at each alarm check valve, and at the fire department connection. Sign layouts and verbiage shall be in Arabic and submitted for approval prior to fabrication.

Sprinkler System Design Data

a. Hydraulic design shall be based on a maximum available residual pressure of 5.9 bar (85 psig)  at the supply side of the alarm valve.
b. Water supply requirements shall be based on one (1) system operating, plus a maximum of 7.2  /hr (600 gpm) for monitor and hose reel.
c. The minimum operating pressure of any sprinkler shall be .5 bar (7 psig).


All materials and equipment used in the installation of the fire protection systems shall be new and the latest design by the manufacturer. The equipment and materials installed shall be UL listed or FM approved.

Pipe and Fittings

Piping and fittings shall be fabricated, installed and inspected in accordance with NFPA 13 and ANSI standard B31.3. All pipe, fittings and valves shall be per General System and Installation Requirements, section 8.5.


a. Sprinkler systems shall use standard orifice sprinklers rated at 74 °C (165 °F) for ordinary temperature classification, NFPA 13 shall be consulted for special cases such as near uninsulated roofs and near heated sources. Sprinkler heads shall not be altered in any respect, nor have any ornamentation or coatings applied after shipment from the manufacturer. 

b. All sprinkler heads subject to mechanical damage shall be provided with standard sprinkler guards.
c. A spare stock of sprinklers, sprinkler cabinet and sprinkler wrench shall be provided to the Owner for each system. The number of spare sprinklers shall be in accordance with NFPA 13.

Alarm Check Valves

a. The sprinkler valve shall be a divided seat ring, rubber faced clapper, water flow alarm check valve intended for automatic sprinkler service. The valve assembly shall be flanged both ends or combination grooved/flanged ends, with variable alarm trim for vertical installations, rated for 12.1 bar
(175 psig).

b. Each wet pipe sprinkler system shall be complete with all necessary valves and trim including, but not limited to, the following:

(i) Alarm check valve.
(ii) Main drain valve.
(iii) Drip cup.
(iv) Water motor gong with alarm line strainer.
(v) Alarm test valve.
(vi) Retard chamber.
(vii) Water pressure gauge.
(viii) Alarm pressure switch.
(ix) Alarm trim pipe, fittings and valves.

Pressure Gauges

Pressure gauges shall have maximum pressure indications of approximately twice the normal working pressure at the point of installation.

Pressure Switches

Pressure switches for fire alarm condition shall have form “C” contacts designed to change state from  sensing a increase of water flow pressure in the system alarm/test line. The pressure setting at which the contacts open shall be adjustable and shall be capable of being set at a predetermined pressure within the range of 0.14 to 0.21 bar (2.0 to 3.0 psig). The switch shall have a pressure rating of not less than 13.7 bar (200 psig). The switch contact rating shall be 24 volt DC, 0.5 amp (minimum). 

Sprinkler System Installation

a. All work shall be installed in accordance with the applicable requirements of NFPA-13, the  Owner and these specifications.

b. System piping shall be shop fabricated wherever feasible. The piping shall be fabricated in spools limited in size to facilitate handling and installation and any subsequent dismantling for maintenance. The ends of pipe sections to be joined in the field shall be provided with flanges, unions, grooved couplings, or threaded to permit installation or dismantling without welding or cutting.

c. The sprinkler system fabricator may use flanged or butt welded joints for shop fabricated piping  2 1/2 in and larger, and screwed joints for all piping 2″ and smaller. All sprinkler piping shall not exceed the limits for supports as required in NFPA-13.

d. All welding procedures, welders and welding operators shall be qualified in accordance with AWS 10.9, Level AR-3.

e. All pipe hangers installed shall be UL listed or FM approved.

f. Automatic sprinkler system piping shall be supported from the building structural steel or concrete, and is permissible only by methods and at locations approved by the Owner. Sprinkler piping shall not be supported from equipment, other pipe, cable tray, ductwork or other non-structural

g. Any additional structural steel which is required to support the automatic sprinkler piping shall be provided by the Contractor.

h. Cutting, tapping, drilling or altering structural members for the passage of piping or for pipe hanger fastening will not be permitted except with prior written approval. Welding to structural members will only be allowed when called out on the shop drawings and approved in advance. Any site welding will require hot work permits, fire watch and similar standard procedures be followed. All costs for following these procedures will be at the Contractor’s expense.

i. All piping shall be supported using hangers, supports, and fasteners acceptable to the Owner.  Hanger spacing shall be in accordance with NFPA 13. If intermediate steel is required for proper spacing of hangers it shall be provided and shown on the sprinkler shop drawings. Hangers shall be attached only to the structure that will support the load without deformation. 

j. All cutting, fitting or patching of the work for sleeves or openings shall be accomplished by the Contractor under the direction of the Owner. Sprinkler piping passing through fire walls and all floors shall be fitted with sleeves. Sleeves shall extend completely through the construction and shall be cut flush with the finished surface, except for floor sleeves which shall extend from 76.2 mm to 152.4mm (3″ to 6″) above the finished floor. Sleeves shall be of such size to provide a minimum gap  of 12.7 mm ( 1 / 2 in) clearance between the pipe and sleeve on all sides.

Sleeves shall be made of schedule 40, galvanized steel pipe. For fire wall penetrations, the space between the pipe and sleeve shall be packed with an approved fire stop material that will preserve the integrity of the fire rating.  Where exposed pipes pass through floors, walls or ceilings in finished areas (offices, etc.), they shall be fitted with chrome escutcheon plates large enough to completely enclose the hole and sleeve.

Where piping passes through exterior walls the opening shall be filled with a silicone or butyl rubber caulking compound to seal against water, air and sand.

k. Work under this specification shall be coordinated with the work of all other trades to obtain the best arrangement and placing of the equipment and piping to expedite the installation and completion of all work.


Cleaning of the automatic sprinkler system piping and equipment shall be in accordance with manufactures recommendations.

Tests And Inspections 

Testing and inspection of the automatic sprinkler systems shall be in accordance with NFPA 13 and this  specification.

Flushing & hydrostatic Test 

a. Underground mains and lead-in connections to the sprinkler system risers shall be flushed by Owner prior to making the connections to the automatic sprinkler systems. Before installation of sprinkler system heads, the Contractor shall flush all automatic sprinkler system piping at a rate sufficient to produce a velocity of 3.1 meters per second (10 feet per second) in the piping or at the water demand rate of the system, whichever is greater.

b. All sprinkler system piping shall be hydrostatically tested at a minimum pressure of 13.8 bar (200 psig) for a period of 2 hours. During this period, each joint shall be inspected for leakage. Any leakage found shall be corrected and the system re-tested for the full 2 hour period.

Acceptance/Discharge Test

a. Each automatic sprinkler system shall be visually inspected to ensure that it has been installed in accordance with this specification and applicable codes, standards and the system drawings.

b. All acceptance testing shall be done in the presence of the Owner or Client Representative. A minimum of 10 days written notice shall be provided to the Owner prior to each test.

c. All operating parts of the system shall be fully tested to ensure that they are in operating  condition.
d. Isolating valves shall be tested by opening and closing under full water pressure.

e. Alarm gongs, and all alarm switches shall be tested for correct operation and must be tested by operating the inspectors test connection. The Contractor shall leave all systems in service after testing is completed. The Contractor shall prepare and submit to the Owner a “Contractor’s Material and Test Certificate” in accordance with NFPA 13.

Water Spray System

See Specification F-02-E-01 (Fire Protection Systems) Section 17 for details.

Foam System

See Specification F-02-E-01 (Fire Protection Systems) Section 20 for details.

Water Mist System

See Specification F-02-E-01 (Fire Protection Systems) Section 21 for details.

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