NBS fii PUBLICATIONS

' ATI INST. OF STAND & TECH R.I.C.

I III Hill 1 1 II A111D4 llESlb

NBSIR 84-2948

Field Tests of the Smoke Control

System at the San Diego VA

Hospital

John H. Kioto

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

November 1984

• QC- -

100

.U56

84-2948

1984

I c. 2

;S. DEPARTMENT OF COMMERCE IliTIONAL BUREAU OF STANDARDS

KAnONAX EL'PEAU OF STANDARDS

llSRART

NBSIR 84-2948

FIELD TESTS OF THE SMOKE CONTROL

SYSTEM AT THE SAN DIEGO VA

HOSPITAL

John H. Klote

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

November 1984

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. EmMt Amblar. Oinetor

TABLE OF CONTENTS

Page

List of Figures Iv

List of Tables Iv

Abstract 1

1. INTRODUCTION 1

2. SYSTEM PERFORMANCE 2

2.1 Pressure Differences 4

2 . 2 Open Doors 5

3. FIELD TESTS 6

3.1 San Diego VA Hospital 6

3.2 Wing System 8

3.3 Core System 9

4. DISCUSSION AND RECOMMENDATIONS 9

4.1 Interstitial Space 10

4.2 Core 10

4.3 Activation 11

5. ACKNOWLEDGMENTS 11

6. REFERENCES 11

-111-
LIST OF FIGURES

Page

Figure 1. San Diego VA Hospital Typical Floor Plan 13

LIST OF TABLES

Page

Table 1. Smoke control test of San Diego VA Hospital, third

floor, south wing 14

Table 2. Smoke control tests of the San Diego Va Hospital, third

floor, core area 15

-Iv-
FIELD TESTS OF THE SMOKE CONTROL SYSTEM AT THE SAN DIEGO VA HOSPITAL

John H. Klote

Abstract

The Veterans Administration (VA) has sponsored a project at the Center

for Fire Research of the National Bureau of Standards to study smoke control

in VA hospitals and to develop new design approaches and methods of acceptance

testing. This paper is one report of this ongoing project. It presents the

results of a field test on the San Diego VA Hospital.

Key words: air movement; hospitals; interstitial space; pressurization;

smoke control; smoke detector.

1 . INTRODUCTION

Smoke is recognized as the major killer in fire situations [1] . Smoke

often migrates to building locations remote from the fire space, threatening

life and damaging property. As a solution to the smoke problem, the concept

of smoke control has developed in recent years. Smoke control makes use of

mechanical fans to produce airflows and pressure differences that can control

smoke movement.

This paper is a report of work conducted as part of an ongoing project at

NBS sponsored by the U.S. Veterans Administration (VA) to study smoke control

in VA hospitals and develop new design approaches and methods of acceptance

Figures in brackets refer to references at the end of this paper.

- 1 -
testing. The smoke control system at the VA hospital at Bay Pines, Florida

has already been tested [2]. In general the Bay Pines system performed well.

However, there were some problems and specific recommendations were made to

overcome these.

This report describes one day of tests of the smoke control systems at

the VA hospital in San Diego, California intended to identify any obvious

problems and if possible recommend corrections. Even though the performance

of these systems was disappointing, the cause for the poor performance is

identified in this paper and recommendations are made to overcome the problem.

In this paper, the term "smoke" is used in accordance with the ASTM and

NFPA definitions which state that smoke consists of the airborne solid and

liquid particulates and gases evolved when a material undergoes pyrolysis or

combustion [3,4].

2

.

SYSTEM PERFORMANCE

The fire emergency procedures used in hospitals throughout the United

States including VA hospitals rely heavily on horizontal evacuation. Each

floor of a hospital is divided into a number of zones separated from one

another by fire walls and fire doors. Generally, nurses are trained to

evacuate any patients from the room of fire origin and then close the door of

that room. The patients in the zone which includes the fire room then are

evacuated to other zones on that floor. Because of vertical smoke movement,

similar horizontal evacuation may be necessary on floors other than the fire

floor. Ideally the closed doors between the fire and the occupants retard

-2 -
fire spread and smoke movement, allowing sufficient time for fire fighters to

extinguish the fire. There is the option for vertical evacuation from these

other zones if such an extreme measure is deemed necessary.

In practice, the effectiveness of this approach can be reduced by smoke

leakage through building cracks and gaps around doors. The effectiveness of a

barrier in limiting smoke movement depends on the leakage paths in the barrier

and on the pressure difference across the barrier. The pressure difference

depends on stack effect, buoyancy, wind and the heating, ventilation and air

conditioning (HVAC) system whether under normal operation or in a smoke

control mode.

The concepts of zoned smoke control as described in the ASHRAE smoke

control manual [5] can be employed to provide pressure differences and airflows to limit the smoke movement to the zone in which the fire exists.

Because smoke control is a new field, consensus has not been reached as

to what constitutes reasonable design parameters. The ASHRAE smoke control

design manual lists the following areas for which design parameters must be

established:

1 . leakage areas

2. weather data

3. pressure differences

4. number of doors open in the smoke control system.

5. airflow

-3 -
The reader is referred to the general discussion of leakage areas and

weather data provided in the ASHRAE smoke control manual.

2.1 Pressure Differences

It is appropriate to discuss both maximum and minimum allowable pressure

differences across the boundaries of the smoke control zones. The maximum

allowable pressure difference should be a value that does not result in an

excessive door-opening force. However, what constitutes an excessive door

opening force varies with the application. Section 5-2.1. 1.4.3 of the

National Fire Protection Association (NFPA) Life Safety Code [6] states that

the force required to open any door in a means of egress shall not exceed

222 N (50 lb) . Because of the difficulty of evacuating a disabled patient and

because exposure to smoke can adversely affect a person’s physical ability, a

value lower than 222 N (50 lb) seems appropriate. For a door opening force of

111 N (25 lb) and a force of 31 N (7 lb) to overcome the door closer, a door

1.12 m (44 in) wide and 2.13 m (7 ft) high would have a maximum allowable

pressure difference of 63 Pa (0.25 in H2O). For purposes of discussion here,

this will be used as the maximum allowable pressure difference.

In this paper, the criterion for a minimum allowable pressure difference

is that no smoke leakage shall occur from the smoke zone (one in which there

is a fire) to an adjacent zone. The smoke control system must produce sufficient pressure differences so that it is not overcome by the forces of wind,

stack effect, or buoyancy of hot smoke.

A It is obvious that a smoke control system can meet its objectives of reduced

fire deaths, injuries and property damage due to smoke, even if a small

amount of smoke infiltrates the protected areas.

-4 -
A minimum pressure difference of 5 Pa (0.02 in H

2O) suggested in the

ASHRAE manual (section 2.9.2) for sprinklered spaces is used in this paper as

the minimum pressure difference to overcome the effects of buoyancy of smoke

for sprinklered hospital spaces. A minimum pressure difference of 25 Pa (0.10

in H

2 O) suggested in the ASHRAE manual for smoke control systems intended to

withstand intense fires is used in this paper as the minimum pressure difference to overcome the effects of buoyancy of smoke for unsprinklered hospital

spaces. The smoke control system should be designed to produce the appropriate minimum pressure under design conditions of wind and stack effect with

a broken window in the fire compartment. Such an analysis can be performed by

the computer program described in the ASHRAE design manual.

2.2 Open Doors

During a fire, the doors in boundaries of a smoke zone will be closed

except for short intervals when a person is leaving or when a rescuer or fire

fighter enters the smoke zone. Under these conditions, smoke infiltration

into the protected zones is significantly less than when doors are held open.

For purposes of discussion in this paper, smoke leakage through such intermittently open doors is considered insignificant. However, the airflow

produced by the smoke control system sometimes can be sufficient to hold doors

partially open as occurred at the Bay Pines VA Hospital [2]. This was not the

case at the San Diego VA Hospital.

-5 -
3 . FIELD TESTS

3.1 San Diego VA Hospital

The San Diego VA Hospital consists of six stories, each with an

interstitial space above for distribution of heating, ventilation, airconditioning, plumbing and electrical systems. Air handling equipment (fans,

coils, filters, etc.) is also located with the interstitial space. This space

varies in height from 2.4 m (6 to 8 ft) and is separated from the floor below

only by the suspended ceiling system. Except for a few high risk areas, this

nsists of six stories each with an interstitial space above for distribution

of heating, ventilation, air-conditioning, plumbing and electrical systems.

Air handling equipment (fans, coils, filters, etc.) is also located with the

interstitial space. The interstitial space is approximately 2.4 m (8 ft) in

height and is separated from the floor below by only suspended ceiling system.

Except for a few high risk areas, this hospital is unsprinklered.

The top five floors consist of four wings and a central core which

contains the elevators as shown in figure 1. Each wing is served by its om

HVAC system which is, for the most part, a 100% outside air system. The

central core is supplied with air from all the wings but exhausted by a single

fan located in the penthouse. The smoke control system is arranged such that

each floor of each wing is a separate smoke control zone. In the event of a

fire in one of the wings, the HVAC system, controlled by a computer, is put in

the following smoke control mode:

-6 -
1. The supply fan to the zone in v/hich the fire exists (smoke

zone) is shut off.

2. Exhaust fans serving all other wings of the fire floor are

shut off, and exhaust fans serving the wings directly above

and below are also shut off

.

Thus air is being exhausted from the smoke zone and other zones are being

pressurized. The intent is that smoke movement will be limited to the zone in

which the fire exists. This system is activated by pull boxes, water flow

switches, heat detectors and duct smoke detectors.

When the system was designed no provisions were made for a fire in the

central core (see figure 1). However, a core smoke control system is

currently being installed which will operate as follows:

1. Dampers in the duct supplying the core close to shut off

supply air to the core area on the floor (smoke zone).

2. Dampers in the core exhaust system close on all other floors.

3. Exhaust fans serving the wings of the top five floors are

shut off.

This system also is intended to be activated only by pull boxes, water

flow switches, heat detectors and smoke detectors. The dampers for the system

were all installed so that operation could be simulated by manually

controlling the dampers.

-7 -
3.2 Wing System

The third floor south wing was tested as the smoke zone in order to

compare the system performance with NBS measurements of the same system which

were made approximately eight years earlier [7]. The test results from the

earlier study for normal smoke control operation and the results from this

study are listed in table 1. In the previous study the smoke control system

produced only 5 Pa (0.02 in H

2O) from the core to the south wing, while the

current tests produced 10 Pa (0.04 in H

2O). This increase, possibly due to

modifications in construction, still results in a pressure difference

considerably below the minimum pressure difference for an unsprinklered space.

It was hypothesized that this poor performance was due to exceptionally

high leakage from the outside to the south wing. This would result in exhaust

air being pulled directly from the outside rather than through the core.

Leakage areas were evident in the gaps around the exterior six doors of this

wing to the outside balcony. These door gaps were sealed with tape and the

system was retested (table 1). The pressure difference from the core to the

south wing had increased to 12 Pa (0.05 in H

2O) which was still below the

desired minimum pressure difference but which indicated that at least some of

the poor performance was due to high leakage from the outside.

The suspended ceiling separating the building space of the south wing and

its interstitial space had several obvious openings at poorly fitting tiles

and missing tiles in addition to the normal cracks between tiles and suspension system. In addition, the interstitial space had several vents directly

to the outside. Because it was suspected that air flow from the outside

-8 -
through these vents and then through the suspended ceiling reduced the smoke

control system effectiveness, these vents were blocked off and the system

retested. This increased the pressure difference from the core to the south

wing to 15 Pa (0.06 in H

2O).

3.3 Core System

The core smoke control system was tested on the third floor and the test

results are listed in table 2. In these tests the pressure differences

between all the wings and the core are Important. The low pressure differences across these boundaries in the normal smoke mode (table 1) was probably

due to Insufficient exhaust capacity. Inspection of the core indicated that

it was relatively air tight to the outside as compared to the south wing.

This led the testing team to suspect that if one or more paths for air from

the core to the outside existed, then increased flow from the wings would

result in increased pressure difference. To test this hypothesis three of the

windows in the core were opened and the pressure differences increased from a

range of 5 to 7 Pa (0.02 to 0.03 in H

2O) to a range of 12 to 20 Pa (0.05 to

0.08 in H

2O).

4. DISCUSSION AND RECOMMENDATIONS

Currently an engineering study is underway to examine alternatives to

improve fire safety at the San Diego VA Hospital. The minimum pressure

difference to which a smoke control system should perform will depend on

whether spaces are to be sprinklered. The following discussion and recommendations are provided in the hope that they will be useful for this engineering

study.

-9 -
4.1 Interstitial Space

The vents from the interstitial space to the outside should be closed.

This will improve the performance of the smoke control system in the third

floor south wing, and probably in all the other wings because of similar

construction. Further with the vent open it is questionable whether the

interstitial space exhaust is capable of preventing smoke downflow through the

suspended ceiling from the interstitial space. Smoke from a fire in a

building space can flow up through the ceiling system into the interstitital

space, cool and then flow down through the ceiling into a remote space thereby

causing hazardous conditions. It has been shown by Klote [8] that this hazard

can be prevented by use of an interstitial space exhaust at a rate of two air

changes per hour, provided that the leakage area between the interstitial

space and the outside is relatively small. The exhaust capacity of the interstitial space should be reexamined. If it is below two air changes, it should

be Increased to, and possibly above this value if improved smoke control

system performance is desired.

4.2 Core

The system being installed in the core should be reevaluated because of

its poor performance. Its capacity can be increased by increasing the exhaust

capacity or by the addition of vents from the core directly to the outside.

Such vents should be located on at least two opposite outside walls to minimize any adverse effects of the wind.

- 10-
4.3 Activation

Smoke control system activation by pull boxes should be reevaluated.

Pull boxes activate the smoke control zone in which they are pulled. However,

it is conceivable that they might be pulled in a zone other than the fire

zone, resulting in the system aiding smoke spread rather than preventing it.

If possible, activation should be by means of open area smoke detectors,

sprinkler water flow, or both. Activation only by duct detectors is not

recommended because of the long response time and the maintenance problems

associated with these units.

5 . ACKNOWLEDGMENTS

Thanks are due to the staff of the San Diego VA Hospital for their aid

and cooperation during these tests. Appreciation is specifically expressed to

William Schmidt and Lyle Clark of the Veterans Administration.

6. REFERENCES

[1] Berl, W.G. and Halpin, B.M. , Human Fatalities from Unwanted Fires, Johns

Hopkins APL Technical Digest, Vol. 1, No. 2, p. 129-134, 1980.

[2] Klote, J.H., Field Tests of the Smoke Control System at the Bay Pines VA

Hospital, Nat. Bur. Stand. (U.S.), NBSIR 84-2868, May 1984.

[3] Annual Book of ASTM Standards, Part 18, ASTM E176-80, American Society

for Testing and Materials, Philadelphia, PA, 1980.

[4] Standard for the Installation of Air Conditioning and Ventilating

Systems, NFPA 90A-1981, National Fire Protection Association, Inc.,

Quincy, MA, 1981.

[5] Klote, J.H. and Fothergill, J.W., Design of Smoke Control Systems for

Buildings, American Society of Heating, Refrigerating, and AirConditioning Engineers, Atlanta, GA, 1983.

- 11 -
[6] Code for Safety to Life from Fire in Buildings and Structures, NFPA

101-1981, Quincy, MA, National Fire Protection Assn., 1981.

[7] Fung, F.C.W. and Zile, R.H., Test and Evaluation of the Smoke Control

Capabilities of the San Diego Veterans Administration Hospital, Nat. Bur.

Stand. (U.S.), NBSIR 77-1225, April 1977.

[8] Klote, J.H., Smoke Movement Through a Suspended Celling System, Nat. Bur.

Stand. (U.S.), NBSIR 81-2444, Feb. 1982.

- 12-
Outside

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Figure

1.

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VA

Hospital

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Plan
Table

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control

test

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VA

Hospital,

third

floor,

south

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14
Table 2. Smoke control tests of the San Diego VA Hospital

»

third floor, core area

Normal Smoke

Mode

Three Open

Core Windows

Location (Pa) (in H2O) (Pa) (in H2 O)

South wing to the core (Door 1) 5 0.02 12 0.05

West wing to the core (Door 2) 7 0.03 20 0.08

North wing to the core (Door 3) 7 0.03 12 0.05

East wing to the core (Door 4) 7 0.03 12 0.05

South elevator (Door 5) 0 0 7 0.03

15
NBS-114A (REV. 2-8C) U.S. DEPT. OF COMM.

4.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 84-2948

2. Performing Organ. Report NoJ 3.

TITLE AND SUBTITLE

Publication Date

November 1984

Field Tests of the Smoke Control System at the San Diego VA Hospital

5. AUTHOR(S)

Dr. John H. Klote

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struction s) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

The Veterans Administration (VA) has sponsored a project at the Center

for Fire Research of the National Bureau of Standards to study smoke

control in VA hospitals and to develop new design approaches and methods

of acceptance testing. This paper is one report of this ongoing project.

It presents the results of a field test on the San Diego VA Hospital.

12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) air movement; hospitals; interstitial space; pressurization; smoke control;

smoke detectors

13. AVAILABILITY

Unlimited

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