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Stairwell Pressurization

Irwin A. Benjamin and John H. Klote

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

June 1979

Final Report

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STAIRWELL PRESSURIZATION SYSTEMS

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Irwin A. Benjamin and John H. Klote

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

June 1 979

Final Report

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Director

TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES iv

Abstract 1

1. INTRODUCTION 1

2. SINGLE INJECTION SYSTEMS 2 2.1 Bottom Injection 2 2.2 Top Injection 2

3. COMPARTMENTAL I ZATI ON OF STAIRWELL 3

4. MULTIPLE INJECTION SYSTEMS 3 4.1 Multiple Injection with an Exhaust Fan 3

4.2 Multiple Injection with Modulating Dampers 3 4.3 Multiple Injection with an Exhaust Duct System 4

4.4 Multiple Injection with Barometric Dampers 4

5. FIELD TESTS 5 5.1 Instrumentation 5 5.2 Tracer Test Procedure 5 5.3 Building No. 1 5 5.3.1 Pressure-Velocity Tests 6

5.3.2 Tracer Test 6

5.3.3 Smoke Candle Test 7 5.4 Building No. 2 7 5.4.1 Pressure-Velocity Tests 8

5.4.2 Tracer Test 8

6. DISCUSSION 9

7 . REFERENCES 11

iii
LIST OF FIGURES

Page

Figure 1. Diagram of bottom injection stairwell pressurization

system 15

Figure 2. Diagram of top injection stairwell pressurization

system 16

Figure 3. Compartmentalization of stairwell in the IDS Center

in Minneapolis 17

Figure 4. Multiple injection system with an exhaust fan and a roof mounted supply fan 18

Figure 5. Multiple injection system with an exhaust fan and

several wall mounted supply fans 19

Figure 6. Typical floor plan for Building No. 1 20

Figure 7. Diagram of stairwell pressurization system for

Building No. 1 21

Figure 8. Second floor plan for Building No. 1 22

Figure 9. SF concentrations for Building No. 1

D 23

Figure 10. Typical floor plan for Building No. 2 24

Figure 11. Diagram of stairwell pressurization system for

Building No. 2 25

Figure 12. Second floor plan for Building No. 2 26

Figure 13. SF. concentrations for Building No. 2 27

LIST OF TABLES

Page

Table 1. Differential pressures across stairwell doors

and average supply and exhaust velocities for

Building No. 1 13

Table 2. Differential pressures across stairwell doors

and average velocities at supply grills for

Building No. 2

iv
STAIRWELL PRESSURIZATION SYSTEMS

Irwin A. Benjamin and John H. Klote

Abstract

The use of stairwell pressurization systems has

grown in the U.S. over the past few years. However,

there are no accepted design procedures for the systems. The paper discusses several of the designs now being used in the U.S., with some of the assumptions

used for design of the systems. In particular, single

and multiple injection systems are discussed. A report

is made on field tests on two systems. The testing

is part of a continuous program to evaluate alternate systems, in an attempt to establish design

recommendations for the future.

Key words: Bottom injection; multiple injection; smoke

candle test; smoke control; stairwell pressurization;

top injection; tracer gas test.

1. INTRODUCTION

Smoke is recognized as a major killer in fire situations. Smoke

movements in high-rise buildings are primarily caused by the bouyancy

forces of hot gases and by stack effect due to indoor and outdoor temperature differences. These forces usually cause smoke to travel up stairwells, elevator shafts, mechanical shafts and even mail chutes. This

vertical movement through these shafts speeds up smoke infiltration of

the upper floors. In addition, the smoke logged stairwells and elevator

shafts block evacuation and obstruct fire fighting. Benjamin, Fung and

Roth [1]-*- provide the principle of smoke movements in buildings.

In an effort to provide smoke-free stair passages during the fire,

a number of stairwells have been built with pressurization systems.

Ideally these systems use air pressure to prevent smoke infiltration. A

number of papers and articles have been written concerning the analysis

and design of pressurized stairwells [2-5]. Tamura and Shaw [6] generated

detailed data on air flow in stair shafts.

Pressurized stairwell systems maintain design pressures when all the

stairwell doors are closed. These pressures may result in unreasonably

high door opening forces. However, when only one door is opened the

pressure drops dramatically. In some cases the opening of only a few

doors can cause system failure since the drop in stairwell pressure will

allow reverse air flows from the building into the stairwell.

Numbers in brackets refer to the literature references listed at the

end of this paper.

1
With the increase in building code requirements for pressurized

stairwells and the lack of any explicit design criteria there has arisen

a multiplicity of design practices in the U.S.A. Many designers have

approached the problem with novel solutions, using a variety of design

assumptions. In view of the diversity of approaches, NBS has undertaken

a study to catalog the many ideas being used and make this knowledge more widely available. The current program has a twofold purpose:

1. To list the many pressurization schemes being used.

2. To evaluate by field tests the efficacy of some of the schemes.

This paper is a preliminary report oriented to this goal and

contains a report of the field tests on two different pressurized

stairwells

2. SINGLE INJECTION SYSTEMS

The single injection system uses only one blower to introduce

pressurized air into the stairwell.

2.1 Bottom Injection

The bottom injection system has pressurization air supplied at the

stairwell bottom and may have an exhaust vent or fan located at the top.

Figure 1 is a diagram of a bottom injection system. The Polytechnic

Institute of Brooklyn has performed extensive tests on a 22 story bottom

injection system [10]. This system had an injection rate of 14000 l/s

(30,000 cfm) and an exhaust rate of 3800 £/s (8,000 cfm) . With all the

doors closed the differential pressure across the first floor door was

260 pascals (1.05 inches H2 O) . Under these conditions the first floor

door would require approximately 310 newtons (70 pounds) opening force.

When the doors on the 6th, 7th and 8th floors were all open, the system

failed to maintain positive pressures within the stairwell above the

tenth floor. The reason for this failure was that the stairwell exhaust

fan pulled air from the upper floors into the stairwell. The New York

City Local Law 5 required stairwell pressurization by such a bottom

injection system with a roof mounted exhaust. Because these systems are unworkable for tall buildings, the New York Supreme Court rendered this

law void in January 1977.

2.2 Top Injection

The top injection system has pressurization air supplied at the top

and may have an exhaust vent or fan located at the bottom. Figure 2 is a diagram of such a system. Tests on a 12 story top injection system were performed by Fung [11]. In this system, the ground level door has

2 Pressurized stairwells are required by the Standard Building Code [7],

the Basic Building Code [8], the Uniform Building Code [9], and many

local building codes.

2
an automatic opening device connected to the building fire alarm system.

The injection fan supplies air at 5400 i/s (11,500 cfm) and all the

doors are weather-stripped to reduce losses. The system was tested with

only the ground floor door open and then with the eleventh floor and the

ground floor doors open. Under these conditions the system maintained

sufficient pressure differentials. However, no tests were made with

more doors open as would likely be the case during a real fire situation.

In addition, the success of this system depends upon weather-stripping,

which may be subject to damage during the life of a building. Nonetheless, the study did show that top injection systems can be successful

for short stairwells.

3. COMPARTMENTALIZATION OF STAIRWELL

In order to maintain differential pressures in tall stairwells, the

stairwell can be divided into compartments. This was done with a 50

story stairwell at the Investor’s Diversified Services (IDS) Center in

Minneapolis [12]. Figure 3 is a diagram of this system. The stairwell

is divided into three 14 story compartments and one 8 story compartment.

Each compartment is separated from the others by partitions with doors.

Approximately 3800 i/s (8,000 cfm) of air is supplied to each compartment

from the normal building supply air systems. In order to maintain a maximum pressure of 37 pascals (0.15 inch H 2 O) the position of the supply

dampers is controlled by a static pressure sensor located within the

stairwell. This stairwell has been tested by Integrated Systems Inc.,

however, the test results are not yet available.

4. MULTIPLE INJECTION SYSTEMS

Another approach to maintaining pressure in tall stairwells is

multiple injection. In general, these systems have an air supply at a number of floors over the height of the stairwell. Following is a description of some of the different multiple injection systems.

4.1 Multiple Injection with an Exhaust Fan

Two different variations of this system have been observed in

existing buildings in Nashville, Tennessee. One has a roof mounted

supply fan as shown in figure 4. The other has individual wall mounted

supply fans as shown in figure 5. The wall mounted fans represent a considerable cost saving as opposed to the roof system which required

construction of a separate duct chase. Later in this report there is a discussion of field tests on two stairwells with roof mounted fans.

There are also plans to field test the system with the wall mounted fans

in the near future.

4.2 Multiple Injection with Modulating Dampers

In this system the stairwell pressure is maintained by controlling

the position of the supply dampers by a static pressure sensor which

3
senses the differential pressure between the stairwell and the building.

This is essentially the same control method used in the IDS Center

stairwell. A multiple injection system with this control system was installed in a 36 story building owned by the Commercial Union Assurance

Companies, Boston [13]. This system has 14 supply air points and 13

static pressure sensors located at various heights in the stairwell.

The system is supplied from two fans located on the 12th and 36th floors.

The system was designed to maintain differential pressures in the range

of 1.25 pascals (0.005 inches H 2 O) to 100 pascals (0.4 inches H 2 O) with

total air injection of 33,700 %/s (71,500 cfm) . This system was tested

by the design engineers. With all doors closed the differential pressures

ranged from 95 pascals (0.38 inches H

2 O) to 5 pascals (0.02 inches H 2 O)

With five doors open the differential pressures ranged from 20 pascals

(0.08 inches H 2 O) to 2.5 pascals (0.01 inches H 2 O) . The pressure of 2.5

pascals is sufficient to prevent infiltration of cold smoke.

4.3 Multiple Injection with an Exhaust Duct System

This system uses the natural resistance of a ducted exhaust system

to control differential pressures. When all the stairwell doors are closed air is relieved through the exhaust duct system preventing

excessive pressure buildup and thus preventing excessive door opening

forces. However, when one or more doors are open the stairwell pressure

drops and flow through the exhaust duct will correspondingly decrease.

Ideally this allows sufficient stairwell pressures to prevent smoke

infiltration when several doors are open. This system eliminates the

static pressure sensors and modulating supply dampers of the previous

system and therefore most likely increases reliability. Such a system was designed for a 31 story office building in San Francisco. The

system was designed with supply rate of 280 %/s (600 cfm) per floor or 8780 %/s (18,600 cfm) total supply air. The system was balanced by

adjusting the free area of the supply and return grills. Pressure tests

of this system have not yet been performed.

4.4 Multiple Injection with Barometric Dampers

This system operates in a similar manner to the previous one except

that the pressure is regulated by a barometric damper rather than the

exhaust duct system. When all the doors are closed the barometric

damper is open preventing excessive stairwell pressures. However , when

a door opens, the stairwell pressure drops causing the barometric damper

to close. This should allow sufficient stairwell pressure to prevent

smoke infiltration. This system eliminates the need for an expensive

exhaust duct system. This type of system has also been designed for the

16 story Affiliated Hospital Center in Boston. As in the previous

system this was designed with a supply rate of 280 %/s (600 cfm) per

floor. Pressure tests of this system have not yet been performed.

4
5. FIELD TESTS

Field tests were performed on two stairwells with multiple injection

systems in different buildings in Nashville, Tennessee using sulfur

hexafluoride (SF^) as a tracer. Both stairwells have roof mounted

exhaust fans, as required by the Standard Building Code [7].

5.1

Instrumentation

Velocity measurements were performed using a thermo-anemometer.

Static pressure differences were measured by a Magnahelic pressure

gauge. SF$ samples were analyzed by a portable gas chromatograph having

an electron capture cell fitted with a 300 me tritium source.

5.2

Tracer Test Procedure

The tracer gas, SF5 , was released at a relatively constant rate

from a simulated burn room. Samples throughout the building were taken

and analyzed to determine smoke movement in the event of a real fire.

The burn room doorway was covered with a cardboard mask in which a fan was located. The fan produced a constant flow of air mixed with SF 5 from the burn room into the corridor. The SF5 flow was produced by a slight turn of a needle valve producing burn room concentrations of 550

ppb for the test on Building No. 1 and 350 ppb for the test on Building

No. 2. Data reduction of samples less than 200 ppb was by means of

interpolation between several data points. These data points were

obtained by different dilutions of a standard SF5 sample of concentration

200 ppb. Data reduction of higher concentration samples was by means of an empirical relationship developed by Hunt and Treado [14]. In future

tests lower burn room concentrations will be attempted to eliminate the use of the empirical formula and to allow operation in the more sensitive

region of the gas chromatograph.

5.3

Building No. 1

Building No. 1 is an eight story apartment building for the aged.

Figure 6 is a typical floor plan. When these tests were performed,

construction of the building had just finished but the building was unoccupied. Consequently, the building was initially unheated. However, the building manager was able to supply heat for the SF 5 test.

Both stairwells have the same pressurization system design therefore

tests were performed primarily on Stairwell No. 2. Figure 7 is a diagram of this pressurization system. The system has a roof mounted

exhaust fan and a roof mounted supply fan which supplies pressurization

air through a masonry shaft 0.46 m by 1.07 m (1.5 ft by 3.5 ft). The

supply shaft is located next to the stairwell and there is an injection

point at each floor. The supply fan had a rated capacity of 3800 l/s

(8,000 cfm) at 156 pascals (0.625 inches H2 O) . The exhaust fan had a rated capacity of 1180 l/s (2,500 cfm) at 31 pascals (0.125 inches H2 O).

5
5.3.1 Pressure-Velocity Tests

Supply and exhaust velocities and differential pressures across stairwell doors were measured with the pressurization system operating.

The results of these tests with all doors closed and with some doors

open are listed in table 1. Velocity measurements were taken approximately 0.05 m (2 inches) in front of the supply and exhaust grills.

Average velocities were obtained by making a transverse of six points.

Because the velocity measurements were taken in front of the grills,

they cannot be used to determine accurate volumetric flow rates. However, some useful observations can be made from the velocity data. The

supply system was very unbalanced with velocities varying from 0.3 to

2.9 m/sec (60 to 570 ft/min) with all the stairwell doors closed.

Furthermore, when doors are open all the velocities increase with the

largest increases at the floors where the doors are open. This is

probably due to increased fan flow rate when it is operating at a lower

static pressure. When two doors are opened the exhaust velocity decreases

as might be expected. However, when three doors were open the velocity

increased, which was unexpected. This may have been caused by the fan

controls which were designed to maintain relatively constant flow.

With all the doors closed the system maintained pressures in the

range of 60 to 67 pascals (0.24 to 0.27 inches H2 O) . When two doors

were open this pressure dropped dramatically. The pressures generally

dropped more when additional doors were opened. The exception to this was the differential pressure across the roof door. However, the pressure differential was with respect to the outside and was therefore

greatly affected by the wind. In addition, the roof door was tightly

weather-stripped and had to be cracked open for the differential pressure

measurement. This caused an error for the roof door pressures on the

low side by as much as 7.5 pascals (0.03 inches H2 O)

5.3.2 Tracer Test

For the tracer test the building was heated to 21° C (70° F) . The

simulated burn room was located on the second floor as shown in figure

8. The elevator lobby doors were closed on all floors except for the

doors on the second floor on the side of the lobby leading toward the

burn room. Under normal conditions this door would have been closed,

however, it was left open under the belief that this would be a more severe test of the stairwell pressurization system. Figure 9 shows the

SF^ concentrations during this test. On the second floor, the SFf,

concentration is much lower at the corridor outside of Stairwell No. 2 than at the elevator lobby, indicating that the air flow direction is

from the stairwell to the elevator lobby. At 15 minutes the stairwel

concentrations were below 2% of the burn room concentration. The concen- tration remained below 2% at the second floor of the stairwell but it rose to 7.5% on the eighth floor. This concentration is quite high

considering that all the stairwell doors were closed and stairwell

differential pressures were at the maximum.

6
At approximately 33 minutes into the test a sample was taken

directly from the supply grill in the stairwell on the first floor. The

concentration was 6.2% of the burn room. Next a sample was taken at the

inlet to the supply fan on the roof. This was 3.3% of the burn room. The wind was 1.8 to 5.1 m/sec (350 to 1000 ft/min) southwest and appears

to have carried the SF^ from the roof vents into the supply fan inlet.

Air samples were taken at a number of locations on the roof and the SFg

concentration ranged from 4.5 to 100% of the burn room. The highest

concentrations were near the elevator vent which was located approximately 30 m (100 ft) from the inlet to the stairwell pressurization fan.

A spot check of Stairwell No. 1, at the opposite end of the building,

gave an SF 5 concentration less than one percent of burn room.

5.3.3 Smoke Candle Test

A smoke candle test was performed to visually determine the exact

path of SFg tracer into Stairwell No. 2. Two smoke candles (3-minute

duration) were simultaneously ignited in the second floor corridor

in front of the burn room of the SF 5 test. The fan in the burn room doorway was operating in order to reproduce the conditions of the

earlier test. As in the earlier test the fire doors to the elevator

lobby were closed on all floors with the exception of the doors on the

second floor lobby toward the burn room.

Upon ignition of the candle the corridor filled rapidly with smoke.

Three apartments on the fire corridor were occupied by members of the

Nashville Fire Marshal's office. Smoke leaked into these apartments

through cracks around the closed doors forcing the occupants to windows

and balconies. After the corridor had filled with smoke, the door to

Stairwell No. 2 was opened. The air flow from the pressurized stairwell

forced the smoke down the corridor to within 1.5 m (5 ft) of the smoke

candles. This resulted in a section of corridor 6 m (20 ft) long,

between the room and the stairwell, which was relatively free of smoke.

A small quantity of smoke emerged on the roof from a toilet exhaust fan

which was not operating because the building was unoccupied. This was shortly followed by a large quantity of smoke flowing from the elevator

vents. This flow lasted about 20 minutes and was carried by the wind in

the direction of the pressurization fan for Stairwell No. 2. However,

the smoke was considerably diluted when it reached the fan intake.

Throughout the smoke candle test, smoke was not visible in the stairwell

and only the faintest smoke odor could be detected in the stairwell.

5.4 Building No. 2

Building No. 2 is nominally a 16 story apartment building for the

aged. Figure 10 is a typical floor plan. The floor numbering system

used for this building eliminated the thirteenth floor so that the

fourteenth floor is directly above the twelfth floor. At the time of

these tests the building construction was not finished. During the test

interior construction was underway in the north and south wings.

Construction was finished on the east wing which was partially occupied.

7
Tests were therefore limited to Stairwell No. 3. Figure 11 is a diagram

of this pressurization system. During normal operation this system

supplies conditioned ventilation air to the corridors. There are corridor supply grills on each floor but there are only six stairwell

supply grills. The stairwell supply grills are located at the landings

just above the 2nd, 3rd, 6th, 9th, 12th and 17th floors. In a fire

situation dampers leading to the corridor supply grills close and

dampers to the stairwell supply grills open. Pressurization air is

supplied by a roof mounted air handling unit which contains heating and

cooling coils and a fan of rated capacity of 5000 l/s (10,500 cfm) at

250 pascals (1.0 inch H2 O) . The roof mounted exhaust fan was rated at

1180 l/s (2,500 cfm) at 31.3 pascals (0.125 inches H2 O)

A static pressure sensor located in the sixth floor of the mechanical

shaft was designed to control the exhaust fan. When the pressure difference between the stairwell and the mechanical shaft reaches 75 pascals

(0.3 inches H2 O) the exhaust fan dampers are opened and the exhaust fan

is turned on. However, in these tests the pressure differential never reached 75 pascals and accordingly the exhaust fan was never actuated.

5.4.1 Pressure-Velocity Tests

Supply velocities and differential pressures across stairwell doors were measured with the pressurization system operating. The results of

these tests with all doors closed and with some doors open are listed in

table 2. When the pressurization system was turned on the heating coils

in the air handling unit continued to heat resulting in an average

stairwell temperature of 30° C (86° F) . The tests with all the doors

closed and with two doors open were conducted under these conditions.

The test with three doors open was taken with the heating coil turned

off and an average stairwell temperature of 22° C (72° F) . Velocities

were measured in the same manner as was done with Building No. 1. With

two doors open the differential pressure across the second floor door

fluctuated from an overpressure of 3.7 pascals (0.015 inches H2 O) to a negative stairwell pressure of 3.7 pascals. The negative pressure

indicates a reverse flow of air through doorway cracks into the stairwell.

The velocities do not follow the pattern observed in the earlier tests.

This may have been caused by the varying wind conditions. When two

doors were open the pressures dropped considerably. However, when three

doors were open the pressure at the top was the same as with all doors

closed. This might have been caused by the difference in stairwell

temperatures. The heated pressurization air resulted in lower pressure

differentials than the unheated air. This difference was probably due

to the differences in air densities between the stairwell and building.

The performance of a stairwell pressurization system therefore appears

to be degraded when the pressurization air is heated.

5.4.2 Tracer Test

The simulated burn room was located on the second floor of the east

wing across the corridor from Stairwell No. 3 as shown on figure 12.

8
The fire doors to the elevator lobby were closed on all floors and the

fifth floor door to Stairwell No. 3 was opened. Figure 13 shows the SF^

concentrations during this test. A member of the Fire Marshal’s office

went into the second floor guest room, which is across the hall and one door toward the elevator lobby from the burn room, and collected samples

at the start of the test and every five minutes following. The concen- tration in the guest room increased rapidly and reached 100% of burn

room concentration at 15 minutes. This was due to the corridor pressure

caused by the air leakage from the pressurized stairwell. The elevator

lobby reached 100% of burn room concentration after 30 minutes.

Until 40 minutes all the stairwell concentrations were below one percent. At approximately 27 minutes the ground level door to the

stairwell was held open. This had no effect upon the successful operation

of the pressurization system. The SFg test was performed with the same wind and temperature conditions as the pressure test with three doors

open. However, if the wind and temperature conditions had been similar

to those of the test with two doors open the system might have failed.

The failure of the roof mounted exhaust fan to operate apparently had no adverse effect upon overall system performance. In fact, if the fan

were replaced with a barometric damper the system probably would have

worked as well.

6. DISCUSSION

6.1 The SF^ and smoke candle tests on Building No. 1 illustrated

the possible problem of smoke feedback into a pressurized stairwell.

This situation can exist during special weather conditions and therefore

the test is not readily repeatable. The test does emphasize the importance of specifying adequate separation of vents and exhausts from

supply fan inlets. Even with the smoke feedback, the pressurization

system was partially successful. During the first 15 minutes of the SF^

test the stairwell concentrations were all less than 2% of the burn

room. In a real fire situation this would provide important evacuation

time during the initial stages of the fire. Of course, if the separation

distance between the elevator vent and the fan intake were less, the

contamination would have been much more severe.

6.2 The slight corridor overpressure, from the stairwell leakage,

forced smoke and SFg into the rooms adjacent to the fire corridor.

Generally a slight corridor overpressure is considered advantageous

because it helps to keep the corridor free of smoke from fires originating in adjacent spaces. If a room fire were to develop sufficient

pressure due to thermal expansion and buoyancy it would overcome the

corridor overpressure. This would result in smoke flowing from the fire

room into the corridor. This is the situation which the SF^ tests

simulate and it is a more severe case than many real fire situations.

If the stairwell door is open, a larger corridor overpressure results,

as was the case in the smoke candle test. In cases where the fire in

the room has not reached flashover, this overpressure in the corridor

could prevent smoke from infiltrating the corridor.

9
6.3 The fact that the stairwell exhaust fan in Building No. 2 never operated raises the question of whether stairwell exhaust fans are necessary. Ideally the exhaust fan eliminates smoke which might infiltrate a stairwell and prevents excessive stairwell pressures. However,

in the case of the bottom injection system already discussed, the exhaust

fan pulled air from the upper floors into the stairwell when three lower

level doors were open. At present there is insufficient information to

properly evaluate the value of exhaust fans and further study is needed.

6.4 The heated pressurization air in Building No. 2 resulted in

lower pressure differentials than the unheated air. This difference was probably due to the differences in air densities and indicates that the

performance of a stairwell pressurization system is degraded when the

pressurization air is at a higher temperature than the building.

6.5 Future efforts in this program will include continued testing

of different pressurization systems. The tests of Building No. 2 will

be repeated and expanded when building construction is complete and the

entire heating and cooling system is balanced. Future tests will

investigate the effects of supply air flow rates, weather conditions,

control methods and of different locations of supply air inlets. The

function of exhaust air fans will also be examined.

10
7. REFERENCES

[1] Benjamin, I. A., Fung, F., and Roth, L., Control of smoke movement

in buildings: a review, Nat. Bur. Stand. (U.S.), NBSIR 77-1209

(July 1977).

[2] Cresci, R. J., Smoke and Fire Controls in High-Rise Office Buildings - Part II: Analysis of Stair Pressurization Systems, ASHRAE

Symposium on Experience and Applications on Smoke and Fire Control,

Louisville, Kentucky, June 1973, p. 16-23.

[3] Minni, R. , Smoke Infiltration into the Fire-Escape Routes of Tall

Buildings, CIB Symposium on the Control of Smoke Movement in Building Fires, Vol. I, Watford United Kingdom, Nov. 1975, p. 245-266.

[4] denOuden, L. , The Effect of Opening and Closing of Doors on the

Pressure Levels in a Building in which the Stair-well is Pressurized, CIB Symposium on the Control of Smoke Movement in Building

Fires, Vol. II, Watford United Kingdom, Nov. 1975, p. 42-49.

[5] Hobson, P. J. and Stewart, L. J., Pressurization of Escape Routes

in Buildings, Heating and Ventilating Research Association, Bracknell

Berkshire, England, Jan. 1973.

[6] Tamura, G. T. and Shaw, C. Y. , Air Leakage Data for the Design of

Elevator and Stair Shaft Pressurization Systems, ASHRAE Technical

Paper No. 2413.

[7] Standard Building Code, Southern Building Code Congress International, Inc., Birmingham, AL (1976 Edition with 1979 Revisions).

[8] Basic Building Code, Building Officials and Code Administrator's

International, Inc., Chicago, IL (1978 Edition).

[9] Uniform Building Code, International Conference of Building Officials,

Whittier, CA(1976 Edition with 1979 Revisions).

[10] DeCicco, P. R. , Cresci, R. J., Correale, W. H. , Report of Fire

Tests, Analysis, and Evaluation of Stair Pressurization and Exhaust

in High-Rise Office Buildings, performed for the City of New York

by the Polytechnic Institute of Brooklyn, Baywood Publishing Company,

Sept. 1972.

[11] Fung, F. C. W. , Evaluation of a pressurized stairwell smoke control

system for a 12 story apartment building, Nat. Bur. Stand. (U.S.),

NBSIR 73-277 (June 1973)

[12] Hedsten, G. C., Building and Stair Pressurization System, ASHRAE

Journal, July 1978, p. 32-35.

11
[13] Dias, C., Stairwell Pressurization in a High-Rise Building, ASHRAE

Journal, July 1978, p. 24-26.

[14] Hunt, C. M. and Treado, S. J., A prototype semi-automatic system

for measuring air infiltration in buildings using sulfur hexafluoride

as a tracer, Nat. Bur. Stand. (U.S.), Tech. Note 898 (March 1976)

p. 4.

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13
Table

2.

Differential

pressures

across

stairwell

doors

and

average

velocities

at

supply

grills

for

Building

No.

cm

au o)

a o o) 3 rH ^ WOE> ^

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mm

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14

No

supply

grill

on

this

floor.

r

Ground

level

(Floor

1)

opens

directly

to

outside.
Figure 1. Diagram of bottom injection stairwell

pressurization system

15
Figure 2. Diagram of top injection stairwell

pressurization system

16
Figure 3. Compartmentalization of stairwell in the IDS Center

in Minneapolis

17
Exhaust fan

Figure 4. Multiple injection system with an exhaust fan and a roof mounted supply fan

18
Exhaust fan

Figure 5. Multiple injection system with an exhaust fan and

several wall mounted supply fans

19
20

Figure

6.

Typical

floor

plan

for

Building

No.
Figure 7. Diagram of stairwell pressurization system for

Building No. 1 21
22

Figure

8.

Second

floor

plan

for

Building

No.
90

80

70

60

50

40

30

20

10

0

15 20

Time (Min.)

Figure 9. SF^ concentrations for Building No. 1 23
East wing (to 17th floor)

Figure 10. Typical floor plan for Building No. 2

24
Figure 11. Diagram of stairwell pressurization system for

Building No. 2 25
East wing

N

SW1

NOTE: Drawing not to scale

SW2

South wing

Figure 12. Second floor plan for Building No. 2

26
100

90

80

70

60

50

40

30

20

10

0

Locations

O Stairwell no. 3 2nd floor

A Stairwell no. 3 17th floor

O Guest room 2nd floor

O Corridor 17th floor

Elevator lobby 2nd floor

30

Time (Min.)

Figure 13. SF^, concentrations for Building No. 2 27
NBS-114A iREv. »-78)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 79-1747

pspppsnE

- ,r ''Tv- % Ac«i»siotL*fo.

4. TITLE AND SUBTITLE

STAIRWELL PRESSURIZATION SYSTEMS

5. Publication Date June 1979

Code v*

' v

7. AUTHOR(S)

Irwin A. Benjamin & John H. Klote

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

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

(Same as No. 9)

13. Type of Report & Period Covered Final

15. SUPPLEMENTARY NOTES

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

16. ABSTRACT (A 200-word or leas factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.)

The use of stairwell pressurization systems has grown in the U.S. over the past few

years. However, there are no accepted design procedures for the systems. The paper

discusses several of. the designs now being used in the U.S., with some of the

assumptions used for design of the systems. In particular, sihgle and multiple

injection systems are discussed. A report is made on field tests on two systems.

The testing is part of a continuous program to evaluate alternate systems, in an attempt to establish design recommendations for the future.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Bottom injection; multiple injection; smoke candle test; smoke control; stairwell

pressurization; top injection; tracer gas test.

18. AVAILABILITY [j^j Unlimited

[ ] For Official Distribution. Do Not Release to NTIS

| Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

L

5? Order From National Technical Information Service (NTIS), Springfield, VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

20. SECURITY CLASS 22. Price (THIS PAGE)

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