Sprinklers shall be located, spaced and positioned in accordance with the requirements of this section. The general requirements with which all sprinklers must comply are protection area per sprinkler, sprinkler spacing, deflector position, and obstruction to discharge and clearance to storage.
Area of Coverage
a. Along branch lines. Determine distance between sprinklers (or to wall in case of end sprinkler) upstream and downstream. Compare the value of distance between sprinklers with the double of distance from sprinkler to wall. Higher of the two values will be defined as S.
b. Between branch lines. Determine perpendicular distance to the sprinklers on the adjacent branch lines (or to a wall in case of last branch line) on each side of the branch line on which the subject sprinkler is located. Choose the larger of either twice the distance to the wall or distance to the next sprinkler. This dimension will be defined as L.
The protection area of coverage of a sprinkler will be S x L. Thus, As =S Ã L.
The maximum area of coverage for a sprinkler will vary with the type of sprinkler. However, in any case this value shall not exceed 36 m2 for any type of sprinkler.
In a small room, the protection area of coverage for each sprinkler shall be the area of the room divided by the number of sprinklers in the room.
The maximum allowable protection area of coverage for a sprinkler (As) shall be in accordance with values indicated.
Distance between Sprinklers
The maximum distance permitted between sprinklers shall be based on the centerline distance between sprinklers on the branch line or on adjacent branch lines. The maximum distance shall be measured along the slope of the ceiling. The maximum distance permitted shall be as per values. To minimize the amount of piping used, branch lines are usually spaced as far apart as possible while maintaining even spacing within a room. In case of sloped roof, the spacing of sprinkler is to be measured on the slope of the roof and the maximum distance and areas given shall apply. The distance in such cases should be measured along the slope projected between two sprinklers.
Maximum Distance from Walla
The distance from sprinkler to walls shall not exceed one half of the allowable maximum distance between sprinklers.
The distance from the wall to the sprinkler shall be measured perpendicular to the wall.
Protection area and maximum spacing of sprinklers
|Hazard type||Protection area (m2)||Spacing, m (Maximum)|
Minimum Distance between sprinklers
The minimum distance shall be maintained between sprinklers to prevent the operating sprinkler from wetting the adjacent sprinkler and to prevent skipping of sprinkler. The sprinklers shall not be spaced less than 1.8 m on center unless baffles are present.
The sprinkler shall be located at a minimum distance of 10 cm from the wall.
An example where the method of calculation of sprinkler distance is explained. If the distance of the last branch line from wall is 2.1 m and inter branch line distance is 4.0 m, then twice the distance of last branch line from wall being higher than the inter- branch line distance will be used in determining appropriate distance between sprinklers on branch line For an ordinary hazard application.
Calculate distance between sprinklers
As =12 m2
S x L = 12 m2
L =12/4.2 =2.85 m
Angled and other irregular walls and corners with less than 90Â° angles can cause situations where additional sprinklers are required to protect within a large area. This situation is countered by allowing the maximum distance from a sprinkler to a corner or wall to be slightly increased eliminating the need to install an additional sprinkler.
Illustrates the arrangement for locating sprinklers when there are columns while Fig. 17.16b is the arrangement of sprinklers when there are continuous beams.
In all cases, a minimum of 25 mm clearance is required to be maintained between ceiling and defector to allow for the replacement of upright sprinklers. This distance is measured from ceiling to the sprinkler defector.
Under unobstructed construction, this distance shall be a minimum of 25 mm and a maximum of 305 mm.
Ceiling type sprinklers (concealed, recessed and flush type) shall be permitted to have the operating element above the ceiling and the deflector located nearer to the ceiling. The concern to locate the sprinklers as above is that hot gases from a fire can collect in these spaces and delay the activation of the sprinkler system.
Under obstructed construction, the sprinkler deflector shall be located within the horizontal planes of 25 to 152 mm (1 to 6 inch) below the structural member and a maximum distance of 559 mm (22 inch) below the ceiling/roof deck.
The rule of placing sprinkler as above paragraph has been strictly followed. However, as an exception to this rule, sprinkler can be positioned at or above the bottom of the structural member, provided the distance from the ceiling or roof deck to the deflector does not exceed 559 mm (22 inch). Depicts one such arrangement and illustrates that the sprinkler is positioned within 559 mm (22 inch) of the ceiling so as to not negatively impact sprinkler activation and so that the sprinkler discharge will adequately clear the structural members. Highlights the positioning of sprinkler's deflector above bottom of obstruction so as to avoid obstruction to discharge.
Positioning of sprinklers to avoid obstruction to discharge
|S. no.||Distance from sprinkler to side of construction||Maximum allowable distance of deflector above bottom of obstruction (mm)|
|1||Less than 300 mm||0|
|2||300 mm to less than 450 mm||63.5|
|3||450 mm to less than 600 mm||89|
|4||600 mm to less than 750 mm||140|
|5||750 mm to less than 900 mm||190.5|
|6||900 mm to less than 1050 mm||241.3|
|7||1050 mm to less than 1200 mm||304.8|
|8||1200 mm to less than 1350 mm||355.6|
|9||1350 mm to less than 1500 mm||419.1|
|10||1500 mm and greater||457.2|
But where the depths of structural members are such that compliance with the obstruction rules is not possible, sprinkler would need to be installed in each bay. In these cases, sprinklers are located within 25 to 305 mm (1 to 12 inch) below the ceiling, as they are for unobstructed construction, but they can be located up to 559 mm (22 inch) below the ceiling.
Area of Coverage
The protection area of coverage per sprinkler shall be determined as follows.
Placement of sprinkler in each bay of obstructed construction
a. Along the wall. Determine the distance between sprinklers along the wall upstream and downstream (or to the end wall or obstruction in case of the end sprinkler on branch line). Choose the larger of either twice the distance to the end wall or the distance to the next sprinkler. This dimension will be defined as S.
b. Across the room. Determine the distance from the sprinkler to the wall opposite the sprinklers or to the mid-point of the room where sprinklers are installed on two opposite walls. This dimension will be defined as L.
The protection area coverage of sprinkler will be as = S x L.
The maximum allowable protection area of coverage for a sprinkler (sidewall type).
Maximum Distance between Sprinklers
The maximum distance shall be based on the center line distance between sprinklers on the branch line. The maximum distance shall be measured along the slope of the ceiling where sloped ceilings are provided.
Protection areas and maximum spacing of sidewall sprinklers
|Light hazard||Ordinary hazard|
|1||Maximum distance along the wall||4.6 m||3.4 m|
|2||Maximum room width||3.6 m||3.0 m|
|3||Maximum protection area||12.0 mÂ²||9.0 mÂ²|
Sidewall sprinklers shall be installed along the length of a single wall of rooms or bays in accordance.
Maximum Distance from Walls
The distance from sprinkler to the end walls shall not exceed one half of the allowable distance permitted between sprinklers as per while sprinklers shall be located a minimum of 102 mm from an end measured perpendicular to wall.
Minimum Distance between Sprinklers
Inter-sprinkler distance shall not be less than 1.8 m on center.
The sidewall sprinklers shall be located not more than 152 mm (6 inch) or less than 102 mm (4 inch) from ceiling, moving beyond this range, the sprinkler will take longer time to operate.
The sidewall sprinklers shall be located not more than 152 mm (6 inch) or less than 102 mm (4 inch) from walls to which they are mounted.
Sprinkler shall be located so as to minimize obstruction to discharge or additional sprinklers shall be provided. Sidewall sprinklers shall be installed no closer than 1.2 m (4 feet) from light fixture or similar obstruction. But where distance between light fixtures or similar obstructions are more than 1.2 m (4 feet), the
Positioning of sprinklers to avoid obstructions (sidewall sprinklers)
|S.no.||Distance from sidewall sprinkler to side of obstruction (A)||Maximum allowable distance of deflector above bottom of obstruction (B)|
|1||Less than 1200 mm||0|
|2||1200 mm to less than 1500 mm||25.4 mm|
|3||1500 mm to less than 1650 mm||50.8 mm|
|4||1650 mm to less than 1800 mm||76.2 mm|
|5||1800 mm to less than 1950 mm||102 mm|
|6||1950 mm to less than 2100 mm||152.4 mm|
|7||2100 mm to less than 2250 mm||177.8 mm|
|8||2250 mm to less than 2400 mm||228.6 mm|
|9||2400 mm to less than 2550 mm||279.4 mm|
|10||2550 mm and greater||355.6 mm|
Location of sprinkler shall be decided
Positioning of sprinklers to avoid obstructions (sidewall sprinklers)
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