Nosu627,6274632,632D ,/es.,, APPLICATIONS MANUAL FOR SYSTEM’ PRODUCTS OF : !

COMBUSTION DETECTORS INTRODUCTION

These application notes present Ademco’s recommendations for the proper spacing, placement, zoning and wiring of system ionization detectors. Though we feel.the notes will be of great value to fire engineering Personnel and installers, we wish to point out that they provide general information only. Specific requirements for installation work can be found in local codes having jurisdiction and in relevant standards of the National Fire Protection Association (NFPA). Of spe- cial importance is NFPA Standard 72E “Automatic Fire Detectors 1974” which is frequently referred to in these notes.

!Ile also wish to point out that, although Underwriters Laboratories tests ioniza- tion detectors, it does not evaluate or approve their actual placement. SPAC I NG

Underwriters Laboratories tests ionization smoke detectors in a room having a smooth ceiling with few physical obstructions between the fire source and the detectors. Detectors are placed on 30 ft. (9.IM) centers with no more than 21.2 ft. (6.4M) separating the fire source from the horizontal projection of any detector (See diagram I for the U.L. test layout and Section I7 of U.L. Standard 167 for test detai Is).

DIAGRAM 1

m---w--

Once listed by U.L., detectors may centers so long as:

be installed under ideal conditions on 30’

. Cei I i ng surfaces are smooth . Smooth is defined as actually level or having a slope of I l/2 inches or less per foot. (1)

. No physical obstructions exist between the contents being protected and. a detector.

. Ceilings are less than 16 ft. in height. . Minimal air movement exists in the area being protected. Minimal is

defined as O-IO feet per minute (O-0.05 M/S) (2) . The value and/or combustible nature of the contents to be protected do

not seem to warrant closer spaci ng.

(I) Refer to NFPA Standard 72E, “Automatic Fire Detectors 1974”, Section 2-3. I. I.

(2) Defined by U.L. (See Standard 167, Section 17.2).

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The 30 ft. spacing rule should be examined more closely. Though the detectors in diagram I are horizontally and vertically 30 ft. apart, detectors B and D are 42.4 ft. apart. Quite clearly, detector spacing can exceed 30 ft. and still meet U.L. spacing requirements so long as any potential source ‘of com- bustion is within 21.2 ft. of the horizontal projection of a detector and no more than 900 sq. ft. are being protected by any one detector.

What coverage patterns are permissible and meet U.L. requirements? Startaby tracing a circle with a radius of 21.2 ft. (See diagram 2).

RECTANGLE A = 10”~ 41’ = ilQ SQ. FT. B=lSx39’=5BSSQFT. C=2O’x37’=74OSQ.F1. D=25’x34’=850SQ.FT.

LISTED SPACING = 30’ x 30’ = 900 SQ. FT.

DIAGRAM 2

Then remember that the typical room or area to be protected is rectangular or square in shape. So long as a given rectangular or square area fits within the 21.2 ft. circle, it ma,y be pro- tected by one detector. Dia- grams 3 and 4 show the appli- cation of this rule to detector’ placement in two large rooms. Diagram 5 shows how a lengthy hal I way can be protected by only two detectors under ideal con- ditions.

lo’x41’

L

\

21’

b D

DIAGRAM 3.

LISTED SPACING

DIAGRAM 4

18’5

7 1: 3+

i,

DIAGRAM 5

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Ideal conditions, however, .rarely exist. number of problems:

Installers typically must deal with a

Uneven ceilings or ceilings crossed by beams and joists: (3) Ceiling beams 8 inches or less in depth can be considered equivalent to a smooth ceiling in view of the “spi I I over” effect of smoke. In beam construction over 8 inches in depth, movement-of heated air and smoke may be slowed by the pocket or bay formed by the beams. In this case, from the idea.1 30 ft. centers rule.

spacing must be reduced

and are more than 8 ft. on centers, If the beams exceed I8 inches in depth

each bay must be created as a separate area requiring at’ least one detector.

. Two words of cautionregarding detector placement on beamed ceilings. First, if the beamed ceiling is “smooth” (the beams being less than 8” in depth), mount de- tectors on the bottom of the beams, not in the channels in between (See diagram 6). Second, if reduced spacing is required (the beams are over 8” in depth), run smoke tests to determine proper and adequate spacing.

High Rack Storage and Partitions: High storage racks, partitions, large tall equipment, etc. standing on the floor can block the flow of combustion particles. ‘In the case of racks, it may be necessary to install detectors at several levels to insure quick re- sponse to smoldering fires. In the case of partitions, any partition whose top is less than 18” from the ceiling should be considered a side- wall dividing the area being pro- tected.

DIAGRAM 6

Cei I ing Height: Air near the ceiling and air near the floor are usually about the same temperature. In rooms or areas where the ceiling is also the building roof, certain temperature related problems can exist in day- light hours when the sun is shining. Cei,ling air becomes few degrees warmer than floor air. It can actual ly create a “thermal barrier” which prevents the free flow of combustion particles rising from the floor, Re- member that combustion particles depend on heat to lift them up toward the ceiling. If the “heat lift” is nul lified - the combustion particles have the same temperature as the surrounding air, stratification can occur. Detectors placed above the thermal barrier will not detect the developing fire;especially if it is’small or of the smoldering variety. Under these circumstances; detectors must be placed below the thermal barrier to provide proper protection. To insure optimum response in installations involving high ceilings, NFPA recommends (4) that detectors be installed alternatively * two levels, one half at ceiling level and the other at least three feet below the celling (See diagram 7).

(3) The foIlowing.section is quoted virtually verbatem from NFPA 72E, Section 4-4.6.

(4) NFPA 72E, Section 4-4.5.2

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SMOKE DETECTORS AT CEILING / I \

f”T

_ __/---

3’ MIMIMUM HIGH CEILING AREA

Pratt i ca I factories

ly speaking, therma I or warehouses with

0 l 0 l 0 a 0

l 0 l 0 0 .o 0

/

+ SM&E DETECTOR: BELOW CEILING

-A 7

SECTION AA

DIAGRAM 7

barriers are not present in many installations. In metal roofs, smoke tests should be run on warm,

sunny days to see if a thermal barrier exists.

Peaked. or Sloped Ceilings: NFPA requires(5) that a row of detectors be first spaced and located within three horizontal feet from the peak (See diagrams 8 and 9). Additional detectors should be spaced using a horizontal projection from the cei I ing.

PEAKED CE I L I NGS

(5) NFPA 72E, 4-4.4,

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I ’ I I I

I I I

I I i : I

I I

i I I I I I I I I I

S - LISTED SPACING D - SMOKE DETECTOR

DIAGRAM 9

. Blowers, Fans, Air Ducts: Air movement, caused by heating systems, air conditioners, or simply the entrance of fresh air, present a major prob- lem on many installations. Detectors must be spaced in such a way that air currents do not impede the quick detection of fire. Smoke tests must be run. More information regarding air flows appears below in the place- ment section.

. Burn Characteristics and Va I ue of Contents: If highly flammable materials are being protected, quick fire detection is necessary. Closer spacing of detector; would seem sensible. Likewise, if contents’are valuable - - highly sophisticated and expensive machinery would be an example, detect- ors should be placed closer together.

PLACEMENT

False alarms aggravate customers, annoy fire officials, and cost installation companies money. There is no greater cause of false alarms than improper place- ment of detectors. The best way to avoid false alarms is to not place detectors:

. In dusty or d.irty environments. Dust and dirt can accumulate on a detector’s sensing chamber and make it overly sensitive. can also block chamber air en- trances and make the detect Less sensitive. Be especial Ly careful to avoid areas where

‘.. ‘.: .‘. .‘$&n&&~.‘.;* . . . *.. * : :: .-. . *.. * .*. . *

. . .;,’ ai:> : .,. : -. . * .a- -.

fumigants, fog or mist pro- . . . * * : -- ’ - -- * -. .*.** .*. . ; . .-. . . . . . . . -* . * . : . . . . . ’ : - . .* : ::; ,* .- -. .-’ .; . *, .: , . . .

ducing materials, or sweeping and cleaning compounds are used. DIAGRAM 10

These substances.can cause un- wanted false alarms.

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. Outdoors, in stables, open storage sheds, or other open structures typically affected by dust, air currents or humidity.

. In damp or excessively humid areas. Tiny water droplets can accumulate inside the senking chamber and make it overly sensitive.

. Next to bathrooms with showers: A tremendous amount of humid air is produced during a hot shower. This humid air, if it steadily hits a detector’s sensing chamber, can cause a false alarm.

DIAGRAM 13

. Near areas where combustion products are normal I y present I i, ke kitchens, garages, welding shops, ovens, burners, etc.

DIAGRAM 14

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Near manufacturing areas and battery rooms which produce or have present substantial quantities of vapors, gases .or .f umes. Strong vap.ors, I i ke excessii ve’ hum’i d i ty, can make detectors overly;, sensitive. Gases heavier than air s&h as carbon dioxide can make detectors more sensitive. Gases lighter than air such as helium can make detectors less sensitive. $ero-

‘sol particles such as paint fumes may collect on detection chambers and cause false .alarms. (Note : I f vapors, gases, or fumes present are explosive, special explosion-proof f.ire detection is required. This equipment is not available from Ademco).

In very cold or very hot environments. If detectors are placed in areas where the temperature can drop below 32 deg. F (0 deg. C), ice crystals or conden- sation can appear inside the chamber and make it overly sensitive. If detect- ors are placed in areas where the temper- ature exceeds I20 deg. F (48.9 deg. C), interna I components may break down or not operate proper I y .

1 n “dead a i rrt sbaces between cei 1 i ng and walls. NFPA requi res tha ors be located on the ceiling

t detect- - YLIl llCnL FIRE .-m

not less NEVER HERE II or, if

I2 inches AccEpTAgLE”Elj I- ‘i” than 6 inches from any sidewa on the sidewall, between 6 to from the ceiling.

xb INCORRECT

DIAGRAM 15

INCORRECT

DIAGRAM 16

CEILING

Near fresh air inlets, or excessively drafty areas. Air conditioners, heater fans and fresh air can drive products o combustion away from detectors. Smoke tests should be conducted to determine proper detector distance from such air inlets.

( g I

$ DIAGRAM 17

:$ SIDE WALL 5

SUPPLY

LEE

5, f

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Where shou Id detectors be, p laced? NFPA Standard 72A, Section 3731 states:

“Smoke detectors shall be so located and adjusted to operate reliably in case of smoke at any part of the area protected. The location of detectors should be based upon an engineering survey of the application of this form of protection to the area under consideration. These features include air velocity, number of detectors to provide adequate coverage of cross-sectional areas of the space with respect to travel, diffusion or stratification of smoke;. location of detectors with’respect to exhaust, intake, or circulating blowers; air conditioning facilities, temperature variations, and the like. Such conditions vary with different installations and should be dealt with on the basis of experience in the .serv i ce. I’

Basically, detectors should be installed in all areas where required by the appropriate NFPA standard or the authority having jurisdiction. Where tota I coverage is cat led for, NFPA Standard 72E, Sections 2-6.5 and 2-6.6,should be consulted.

In genera I, a detector should be placed as close to the center of the ceiling as possible. Central location is ideal for .sensing f ires in any part of a room.

/ DIAGRAM 20

Detector placement in the path of air flows toward air inlets or return air ducts is also effective. Smoke tests are again useful in determing proper place- ment; Remember that excessive air flows near a detector can reduce normal coverage and protection.

CEILING

.-

DIAGRAM 19

HERE

If center location is not possible, wall mounting may be permissible. Loca I and state f i re regu I ations should be checked carefully. Wal I mounted detectors should be located 6 to I2 inches from the ceiling and at least 3 feet from any wall junction.

. -

DIAGRAM 21

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ZON I NG

The faster the source of an alarm can be pinpointed, the faster action can be taken. While no formal rules exist in regard to zoning, it is always sensible to zone a system of any size. Experienced installers:

I. Establish at least one zone on every floor protected.

2. Zone natural subdivisions of a building such as separate wings on a single f loor.

3. Minimize the number of detectors on each zone. Though as many as 20 No. 627 or 627D detectors can be put on a single zone monitored by the No. 625 Master Control, putting no more than IO - I5 on a zone may be a good idea to simplify troubleshooti.ng.

CROSS ZON I NG

Ionization detection systems, especially those protecting valuable electronic equipment, are often connected to halon extinguishing systems. If a detector protecting the equipment activates, halon is released to extinguish the fire before it can do much damage.

Ha I on, however, is very expensive. If the alarm is a false alarm, valuable chemicals are wasted and the equipment itself must be cleaned; What pre- cautions can be taken to guard against false alarms?

0 01 0 02

I 01 = ZONE ONE UETECTOR 02 = ZONE TWO OETECTOk

OIAGRAM 22

A simple yet effective way to guard against false halon activation is to cross zone an installation. Instead of having one detector protect valuable equip- *, two detectors are placed close together. Distance between detectors is a matter of engineering judgment. (See diagram 22). One detector is wired to one zone of the control monitoring the system and the other detector to a second zone. The releasing circuit for the halon system is then wired across the normally open “dry” contacts of the zone modules in such a way that both zones (and hence both detectors) must activate before the halon drop circuit is trig- gered.

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Diagram 23 below shows cross zoning wiring for Ademco’s No. 625 control ‘panei .artd one No. 628 zone module:

r B--m,- NO. 625 CONTRO’L 1 r zz628;Nziziy 1

I (ZONE 1) 1 1 (ZONE 2) I,

(N.O.) (Cl (N.C.)

DIAGRAM 23: CROSS ZONING WIRING

Cross zoning is not limited to the protection of expensive equipment. It may be employed wherever extra caution is desired for auxiliary system activation. There are, of course, alternative ways of preventing an unnecessary activation of a ha I on system. Time delays, abort switches or heat activated sensors may be used if they are warranted by engineering judgment and are perm’itted by local codes having jurisdiction.

WIRE SELECTION

All fire alarm system wiring must be installed in compliance with the National Electrical Code (NEC) (6) or local codes having jurisdiction. Proper guage wi re shou Id be used. The NEC specifies (7) that single conductor wires shall be no smaller than I6 gauge, two conductor no smaller than 19 gauge, and five or’- more condu::tor cable no smaller than 22 gauge. Solid copper or bunch-tinned (bonded) stranded copper conductors are permitted. The NEC also specifies that power-limited circuit’wiring may be placed as fallows:(8)

a. Exposed on surface of ceiling and sidewalls or !‘f ished” in concealed spaces. Cable shall be adequately supported.and terminated in approved fittings and installed in such a way that maximum protection against physical injury is afforded by building construct ion such as baseboards, door frames, ledges, etc. When located within 7 feet of the floor, cable shall be securely fastened in an approved manner, such asinsul- ated stapling at intervals of not more than 18 inches.

(6) See NFPA’s National Electrical Code, Article 760.

(7) NEC, Article 760, Section 30a-b.

0 (8) NEC, 760-29.

\.

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b. As protection against physical injury, conductors and cables shall be installed in metal raceway when passing through a floor or wall to a height of 7 feet above the floor unless adequate protection can be afforded by building construction such as detailed in (a) above, or unless an equivalent solid guard is provided.

Conductors used should be-color coded to avoid wiring mistakes.

Conductor size, within the guidelines permissible by the, NEC and/or local codes, depends on loop resistance. Table One below IPsts permissible loop lengths for No. 627 or .627D detector loops monitored by Ademco’s No. 625 control:

Tab le Two below shows maximum power line length for the No. 632 or 6320 detectors:

Wire Size (AWG) Maximum Loop Length

18 I6 14

3900 ft. 6000 ft. 9500 ft.

or 75 ohm max. per zone, which- ever is less

Table One

Table Two

POWER LINE MAXIMUM LENGTH (feet-1

Wire Size l-5

Detectors 6-10

Detectors I l-20

Detectors

I8 350 ft. 175 ft. 95 ft. 16 525 ft. 275 ft. 150 ft. I4 880 ft. 440 ft. 240 ft.

For reference purposes, Table Three below shows wire resistance per 1000 ft. for commonly used. wire sizes:

Tab I e Three

Wire Size (AWG) Resistance/l000 Ft. in Ohms

20 10.35 18 6.5 I6 4. I I4 2.8

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TRANSIENT PROTECTION

External transients, especially lightning induced transients, are often the source of problems on fire system installations. They can cause false alarms under certain circumstances and can damage equipment.

Ademco has always gone to great lengths to make its detectors and controls as “transient proof” as possible. Nevertheless, we still get complaints, from time to time, about transient problems. In an attempt to completely eliminate these problems, we now take the additional step of using metal oxide varistors (MOV’s) on our system ionization detectors and control panels.

On the No. 627 or 627D and No. 632 or 632D detectors, we place a MOV across the power input terminals. On the No. 625 control, a MOV is placed across the AC power input.

We feel that your installers can take additional steps, using MOV’s, to protect your system installations from transients. They can:

I. Place MOV’s between each side of the IZOVAC line and an earth ground (See diagram I 24). If the AC line is multi- phase, a MOV should be placed between each phase of the AC input and earth ground. The J voltage between the various AC 120VAC

phases and ground must be OR MOV

determined to insure that proper 240VAC POWER , CHASSIS

voltage MOV’s are selected. INPUT OR CONDUIT GROUND

CONTROL PANEL

DIAGRAM 24

2. Place MOV’s between each side of the control panel initiating device circuit (the thermal or fire loop) and earth ground (See diagram 25).

INITIATING DEVICE Loop

INDICATING DEVICE 4

LOOP HORN

DIAGRAM 25

3. Place MOV’s between each side of the control panel Indicating device. circuit (bell loop) and earth ground (See diagram 25).

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4. Place MOV*s across the power input terminals of Ijo. 627 detectors purchased before February 28, 1977. (.See diagram 261.

FIGURE 26A NO. 627

FIGURE 268 NO. 632

DIAGRAM 26

MOV’s areavailable from your local electrical supply house or electronics parts distributor, or from Ademco as follows:

USAGE ADEMCO PART # GE PART #

IZOV AC Power Input (controls1 8028 Vl50LAIOA

No. 627 or 627D and No. 632 or 632D Detectors (power loop or bel I loop)

8029 V40lAZA ; :

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