Springfield Daughters of the American Revolution. Illinois. Sp.

Investigation of improved sensor/actuator concepts for residential fire sprinkler systems, final report online

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May 1980



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Prepared for:

Federal Emergency Management Agency
United States Fire Administration
National Fire Data Center
USFA Grant No. 79038

Prepared by:

David C. Doerschuk and Stan E. Kleszczelski
Columbus Laboratories
Columbus, Ohio 43201

January 31, 1980



Table 1. Fire Sensor Criteria 5

Table 2. Sprinkler Actuator Criteria 6

Table 3. Rank Comparison of Fire Sensor Concepts 15

Table 4. Rank Comparison of Sprinkler Actuator Concepts 16

Table 5. Detector Response Time 43

Table 6. Plunge Test Data 47

Table 7. Results of Water Flow Tests 48

Table 8. Results of Hydrostatic Leakage Tests 49


Figure 1. Basic Electric Components to Sense Thermal Signature .... 18

Figure 2. The Unisensor Analog Fire Detector 20

Figure 3. Practical Implementation of the Differentiator 21

Figure 4. The Unisensor Analog Fire Detector 23

Figure 5. Bisensor Fire Detector 24

Figure 6. Dualsensor Fire Detector 26

Figure 7. Converting Fire Detector 27

Figure 8. Counting Fire Detector 28

Figure 9. The Solenoid Valve Actuator 31

Figure 10. The Pyrotechnic Actuator 32

Figure 11. Exploded View of On-Off Pyrotechnic Valve 34

Figure 12. Conventional and Modified Fusible Link Sprinklers 35

Figure 13. Nitinol Link Sprinkler 37




Figure 14. Nitinol On-Off Sensor Actuator 39

Figure 15. System Configuration for Controlled Temperature Tests. ... 41

Figure 16. Threshold Sensitivity as a Function of Temperature 44

Figure 17. Rate-of-Rise Sensitivity as a Function of Temperature. ... 46


Appendix A. Circuit Schematic and Parts List for the Unlsensor A-1

Appendix B. Circuit Schematics for the Counting Digital Fire Detector . B-1

Appendix C. Circuit Schematics and Parts List for the Pyrotechnic

and Solenoid Valve Interface Networks C-1


1. Report No.

4. Titlt aod Subtitle

Investigation of Improved Sensor /Actuator Concepts for
Residential Sprinkler Systems.

3. Recipient's Accession No.

5. Report Date

January 31, 1980

7. Author(»)

David C. Doerschuk and Stan E. Kleszczelski

8. Performing Organization Repi

9. Performing; Organization Naine and Address

Battelle Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201

10. Proiect/Task'ttork Unit No.


11. Contract/Grant No.


12. Sponsoring Organization Name and Address

U. S. Fire Administration
P.O. Box 19518
Washington, D. C. 20234

13. Type o( Report & Period

Final 6/79-12/79


15. Supplementary Notes

Presented in Final Conference at Battelle on December 18,


16. Abstracts

An information search of potential techniques to sense residential fires
and activate water sprinklers was made. Several novel approaches to increasing
sprinkler sensitivity, reducing spurious action, and reducing cost were selected for
laboratory development. Transistor and thermal resistor based electronic fire sensors
were built to actuate a solenoid and pyrotechnic valves. A temerature-sensitive,
shape -recovery, nickel titanium alloy was used to build a simple, modified, conventional
link sprinkler and a sprinkler that automatically turns off after use. Controlled
temperature, temperature response, water flow, and hydrostatic leakage testers were
built. The hardware was tested and recommendations were made for the development
of future systems.

17. Key Uords and Document Analysis. 17a. Descriptors

Fire Detectors

Fire Protection


Residential Buildings



17b. Identifiers/Open-Ended Terms

17c. COSATI Field /Group

18. Availability Statement
Release unlimited

19. Security Class (This

UNCI A9-;iFlF.n

20. Security Class (This


21. No. of Pages

22. Price

FOMM NTia-lB (REV. IO-7ai



USCOMM.DC e2e5-P74


This research and development was sponsored by the U. S. Fire
Administration. The authors appreciate the support and guidance given to the
program by Messrs. Harry Shaw and Allen J. Stephens of the USFA.

Major contributions made to the program at Battelle were by the
authors and Messrs. William G. Atterbury, Brian C. Christenson, and Norman C.
Henderson, all Battelle engineers. Dr. Curtis M. Jackson, a Battelle metallur-
gist, provided helpful advice on the application of Nitinol to fire

Gunnar Heskestad, principal research scientist at Factory Mutual Re-
search Corporation, provided technical suggestions on the "Plunge Test" and
Jerome S. Pepi, Director, R&D, Grinnell Fire Protection Systems Company, sup-
plied practical advice and experimental sprinkler heads that were used in some
of the tests.




USFA Grant No. 79038


U.S. Fire Administration
Federal Emergency Management Agency


Columbus Laboratories

January 31, 1980

It has been estimated that approximately 8,000 persons die each year in
the United States as the result of fires. In addition, many persons suffer
serious injuries, and extensive property damage occurs as a result. The vast
majority of these losses occur in residential fires; thus, home fire safety is
of vital concern to each of us. Many of these deaths and injuries, as well as
a considerable portion of the property damage, could be prevented if adequate
fire protection systems were installed. For example, in one study of 117
residential fires, it was estimated that at least 157 of the 171 deaths involved
could have been prevented, and 181 of the 189 injuries could have been, elimi-
nated. The resultant property damage of these fires, which was estimated at
$2.8 million could have been lowered to between $396,000 to $912,000, depend-
ing on whether a sprinkler or smoke alarm fire protection system (respectively)
were used.

There are a number of things which can be done to improve residential
fire safety and these approaches have been dealt with extensively in the lit-
erature. For example, during the construction phase, techniques and materials
can be used to make the residence fire-resistive, although the contents must

be given similar considerations. Also, the residents can exercise care and
avoid dangerous practices which might cause fires to develop. The careless
use of smoking materials is a factor in 25-30 percent of all single-family
dwelling fire deaths. In spite of these technological and educational possi-
bilities, residential fires will likely occur in the foreseeable future. It
is the objective of this program to investigate concepts that could improve
residential fire safety through rapid response fire sprinkler systems.

Numerous investigations of the use of automatic sprinkler systems for
residences have been conducted, and they are in agreement that these systems
provide the best fire safety currently available. In Europe and the United
Kingdom, sprinkler systems are in common use and have conclusively demon-
strated their value. In Australia and New Zealand, during fires in offices,
hotels, and other light-hazard occupancies where sprinkler systems were
installed, only one fatality occurred during a 80-year period.

One of the criticisms commonly voiced against the residential use of
automatic sprinkler systems is the high cost associated with the high water-
discharge rates which are required by many current codes. Work at BCL as well
as other facilities has shown that it is possible to control residential fires
with relatively low discharge rates. The water rate is small enough to make
sprinkler systems for residential buildings economically acceptable. The
approaches needed to promote low-water-usage sprinkler systems for residences
are reasonablly well known at this time.

Another major problem with the residential use of automatic sprinkler
systems is the possibility of needless actuation. It is essential that any
automatic sprinkler system for home use be designed so that it is sufficiently
sensitive to detect fires before they become well developed.

The spurious actuation of smoke detectors and burglar alarms has been
widely noted. However, while this is primarily a nuisance for these systems,
such actuation for a residential sprinkler system could result in greater
financial loss because of water damage than an actual fire.

The automatic fire-protection system, depending on configuration, can
have numerous components, including fire sensors, electrical power supplies,

alarms, wiring, sprinklers, sprinkler actuators, piping, and water supply.
The two most important functions of an automatic fire protection system are
fire detection and fire containment. Detection is required to initiate
containment and alarm occupants; containment is required to allow occupant
escape and reduce property damage. On this basis the Battelle approach is
directed toward the system components that detect and protect, namely sensors
and actuators. Battelle believes that application of new technologies to
sensors and actuators is the critical requirement for innovation. Significant
advances have been made with all the system components; however, sensors and
actuators are the basic components around which the entire system is designed.
Therefore, innovation in these areas will affect all components and allow
design improvements to permeate the entire system.

An automatic fire protection system designed for mass residential
usage must be comprised of small, inexpensive, simple parts. Each part must
be designed for mass production and be of specific reliability. The system
must provide detection of the fire before dangerous heat levels or gas concen-
trations are reached and must activate the minimum water supply required for
containment. Basic requirements are:

• The need for earlier fire detection

• The need for minimum spurious actuation

• The need for reliable operation

• The need for low cost.

Battelle has selected certain technologies that have potential for
solving specific present inadequacies. Battelle searched the literature and
available sources for techniques of fire sensing and sprinkler actuation.
Techniques were evaluated and compared with each other analytically.
Technologies selected for laboratory development were electronics, Mitinol,
and pyrotechnics. Concept models were built and compared with commercial
sprinklers in temperature, water flow, and hydrostatic leakage tests. Several
results are very encouraging and point the way toward a marketable design.
This report contains the results of our technology search, a description of
the hardware models, performance testing results, conclusions as to
applicability of the sensor/actuator concepts, and recommendations that
outline the technical activities required to refine the best program concepts
into marketable equipment.


The purpose of this program is to determine the extent to which the
sensor and actuator functions of residential sprinkler systems could be
improved at a reasonable cost. Ultimately, improved components may result in
increased unit costs; however, total installed cost could possibly be reduced
due to component location and materials. Concepts were originated by an
inhouse search of previous related work and by a literature and telephone
survey. The various techniques for sensing and actuation were evaluated
according to sets of criteria determined by the project team. The criteria
were based on improved and advanced features for residential sprinkler systems
that would reduce costs and increase performance. The best techniques were
selected on this basis, and the hardware development of new components for
each technique was undertaken.

Concepts selected were electronic temperature sensing, pyrotechnic
and solenoid valve actuation, combined sensing/actuation by Nitinol*, actu-
ation by electrical heating of a Nitinol element, and combined sensing/
actuation by a modified eutectic alloy based linkage. The techniques were
tested under conditions of controlled temperature and hydrostatic pressure.
In addition, measurements of thermal response time and water flow were made.
The same battery of tests was applied to selected commercial sprinklers, and
performance comparisons were made.

The experimental results indicate that initial models of electronic
and Nitinol based sprinklers can bracket the performance of conventional sys-
tems in selected tests. Thermal response times have been decreased without
lowering threshold operation levels. Critical water flow and hydrostatic
sealing capabilities have been retained, although continued development in
these areas is recommended. While the electronic components are more expen-
sive than the Nitinol components, both systems are built using relatively
low-cost pieces. Both systems are recommended for continued development and
full-scale testing.

*A nickel titanium alloy that can have a transformation induced shape change
over a prespecified small temperature range.


The concepts were obtained from commercial manufacturers and asso-
ciations, government agencies, and Battelle staff. Sources also included
Thomas Register and the Engineering Index. Two categories of concepts were
sought: fire sensors and sprinkler actuators. Sixteen concepts for fire
sensors and eight concepts for sprinkler actuators were identified and are
evaluated herein. Each concept employs a different principle of operation,
and the various concepts are presently in stages of development ranging from
an idea only to a manufactured product that is widely used. The objective of
this assessment was to select concepts for development that, in Battelle' s
judgment, will most improve the performance and marketability of residential
sprinkler systems.

Evaluation Criteria

The criteria represent major performance attributes that Battelle
considers applicable to residential fire sprinkler systems. The criteria were
selected to each have the same relative order of importance. The fire sensor
and sprinkler actuator criteria groups are ranked in slight descending order
of importance in Tables 1 and 2. When the criteria were used to rank con-
cepts, no weight loading was given to any particular criteria. The purpose of
the evaluation was not to judge small details of one system over another, but
to identify major technology groups with the highest potential for performing
best in most or all of the required attributes.


(1) Response Time

(2) False Alarm Rate

(3) Cost

(4) On-Off Capability

(5) Requirements for Electrical Power or
Auxiliary Equipment


(1) Reliability

(2) Cost

(3) On-Off Capability

(4) Requirements for Electrical Power on
Auxiliary Equipment

How Each Technique Works

The below descriptions feature the principle of operation for each
technique and its developmental status as a fire sensor or sprinkler actua-
tor at the time of survey. Categories are provided for both sensors and
actuators. Some techniques appear in both categories, which indicates the
existence of a combined sensor/actuator; i.e., a frangible glass bulb or fus-
ible link sprinkler. Examples of a sensor only would be electronic tempera-
ture sensors or smoke detectors. Examples of an actuator only would be a
solenoid or pyrotechnic actuated valve. Following the descriptions are rank
comparison tables of all the concepts based on the previous criteria.


1. Frangible Glass Bulb . The bulb, which contains a high vapor
pressure liquid and a small air bubble, is used as a strut to maintain a nor-
mally open water passage. When exposed to heat, the liquid expands, compress-
ing the air bubble. When the bubble is completely absorbed, there is a rapid
increase in pressure, shattering the bulb and allowing water flow. The
desired temperature rating is obtained by controlling the size of the air
bubble relative to the amount of liquid in the bulb. Glass bulb sprinklers
are widely used, relatively inexpensive, and reliable, but do not have the
capability to turn off after use.

2. Fusible Link . This is the most common technique used to sense
fires and actuate sprinklers. Links contain eutectic alloys which melt

rapidly at a predetermined temperature. The eutectic is used to secure a
spring linkage under tension. When the alloy melts, the spring action is used
to open a water passage.

3. Electronic Temperature Sensors . Thermistors, thermal resistors,
and transistors are available which are temperature sensitive and can drive
analog outputs. Relatively inexpensive circuit components can be used to
sense threshold or rate-of-rise and trigger an actuator to remain on for about
ten minutes after the rate-of-rise or threshold fall below preset critical
values. A practical, inexpensive, and safe way to power the electronics is
utilizing available 110 VAC and a transformer rectifier to produce 24 VDC for
the power supply. The transformer rectifier is small and can be centrally
located in the center volume of a protected area. Long-term power drains are
negligible, and the 24 VDC provides reduced human electrical hazards.

4. Electronic Gas Sensors . These devices require a power supply.
They are inexpensive, but are prone to activation by non-hostile sources such
as alcohol, after-shave, or perfume. An example is the Taguchi Gas Sensor,
which is a metal oxide semiconductor responsive to state of oxidation. It can
sense carbon monoxide and hydrocarbon levels, or a lack, of oxygen.

5. Photoelectric and Gas Ionization Smoke Detectors. These devices

require a power supply and are widely used as residential fire alarms. Smoke
detectors operating on the photoelectric principle give somewhat faster re-
sponse to the products generated by fires of low energy (smoldering), as these
fires generally produce large quantities of visible (larger particl-e) smoke.
Smoke detectors using the ionization principle provide somewhat faster re-
sponse to fires of high energy (open flaming), as these fires produce the
smaller smoke particles which are more easily detected by this type of detec-
tor. Neither principle can discriminate between hostile or non-hostile smoke,
which may cause spurious action of a sprinkler system; moreover, decreasing
sensitivity of such devices to small fires results in longer response times to
all fires.

6. Nltinol . Devices powered by Nltinol do not require a power sup-
ply. Energy can be stored in the nickel titanium alloy by physically deform-
ing it to a calculated shape at room temperature. If the shape is heated
beyond a pre-set temperature level, it will exert itself up to 80,000 psi by
"springing" back, to its original shape. Any temperature level can be set
between -60 °F and 250 °F by varying compound amounts of nickel and titanium
which make up the alloy. Nitinol is used for aircraft hydraulic tubing con-
nectors in hard-to-reach areas where they can simply be slipped on by hand
then fastened by application of a hot-air gun. Nitinol has also been used in
heat motors and thermally activated latches. The "memory" of Nitinol was dis-
covered about 15 years ago at the U.S. Naval Ordnance Laboratory, hence the
name Nitinol is an abbreviation for Nickel Titanium Naval Ordnance Laboratory.
It can be made in any form, and the large-volume material cost of a piece
comparable to a fusible link is less than one dollar. The major advantage of
Nitinol over eutectic is that, while both can be made to activate at a preset
temperature, the Nitinol is four to five times stronger. Therefore, Nitinol
sensors can be built smaller and more heat-sensitive. Also, the action of
Nitinol is repeatable and would lend itself to automatic on-off operation,
whereas fusible eutectic alloys are intended for one use only.

7. Ultraviolet and Infrared Flame Detection . Flame detectors opti-
cally sense either the ultraviolet (UV) or infrared (IR) radiation given off
by flames or glowing embers. Flame detectors have the highest false alarm
rate and the fastest detection times of any type of fire detector. Detection
times for flame detectors are generally measured in milliseconds from fire
ignition. Flame detectors are generally only used in high-ceiling areas and
any other areas where hazardous atmospheres in which explosions or very rapid
fires may occur. Flame detectors are "line of sight" devices, as they must be
able to "see" the fire, and they are subject to being blocked by objects
placed in front of them. However, the infrared type of flame detector has
some capability for detecting radiation reflected from walls. Presently, UV
and IR detectors are complex systems of cost beyond a typical homeowners
budget; they also require a power supply.

8» Microwave (Radar) . An antenna, radiometer, and indicator are
used to detect microwave emissions from hot objects. Detectable microwaves
can penetrate wood, asbestos, and roofing materials. These systems require a
power supply and are expensive. The Chasek Engineering Co. of Stamford,
Connecticut proposes to use microwave detection as a fire-fighting technique
to find the "heart" of a fire.

9. Continuous Line Type . Several configurations of this type sensor
are commercially available. One type of line detector uses a pair of steel
wires in a normally open circuit. The conductors are insulated from each other
by a thermoplastic of known fusing temperature. The wires are under tension
and held together by a braided sheath to form a single cable assembly. When
the design temperature is reached, the insulation melts, contact is made, and
a signal is generated. Following a signal, the fused section of the cable
must be replaced to restore the system.

10. Bimetallic . When a sandwich of two metals having different
coefficients of thermal expansion is heated, differential expansion causes
bending or flexing towards the metal having the lower expansion rate. This
action can close a normally open circuit or activate a water valve. Bimetals
are used for the operating elements of several types of fixed temperature
detectors. These detectors are generally of two types: the bimetal strip and
the bimetal snap disc. Drawbacks to the strip type of device are its lack of
rapid positive action and its susceptibility to false alarms from vibration or
jarring, particularly as the rated temperature is approached. Snap-disc
devices are not as sensitive to false or intermittent alarms as the bimetal
strips. Most thermal detectors using bimetal, Nitinol, or expanding metal
elements have the desirable feature of automatic mechanical reset after
operation when the ambient temperature drops below the operating point.

11. Pneumatic . The increased pressure of gas heated in a closed
system can be used to generate a mechanical force which will operate signal
contacts in a pneumatic fire detection device. In a completely closed system
such as a bellows, actuation will occur strictly from a slow change in


ambient temperature, regardless of the rate of temperature change. Some pneu-
matic detectors in use today provide a small opening to vent the pressure
which builds up during slow changes in temperature. The vents are sized so
that when the temperature changes rapidly, such as in a fire situation, the
pressure change exceeds the venting rate and the system is pressurized. These
systems are generally sensitive to rates of temperature rise exceeding 15 °F
per minute. The pressure is converted to mechanical action by a flexible dia-
phragm. This principle has been combined with fusible and bimetallic sensors
to create combined threshold and rate-of-rise detectors. This type sensor may
or may not require a power supply to drive an actuator.

12. Rate Compensation . This detector uses a metal cylinder contain-
ing two metal struts. These struts act as the signal contacts and are under
compression in a normally open position. The outer shell is made of a mate-
rial with a high coefficient of thermal expansion, usually aluminum, while the
struts, usually copper, have a lower expansion coefficient. When exposed to a

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Online LibrarySpringfield Daughters of the American Revolution. Illinois. SpInvestigation of improved sensor/actuator concepts for residential fire sprinkler systems, final report → online text (page 1 of 4)