Coast Guard Conducts Tests on Ship Engine Room Fires
Interesting Procedures Developed in Extinguishing Fuel Oil Fires with Fog in Engine Rooms in Ships
TO fully understand and evaluate water as a fire extinguishing agent, it is necessary to recall to mind the following characteristics and data.
Water is the most efficient heat absorbent substance which can be economically employed for the purpose of controlling and extinguishing fire. It is a liquid at temperatures ranging from 32°F. to 212°F. with a freezing point of 32°F. and a boiling point of 212°F.
A British thermal unit (B.t.u.) is that volume of heat which is required to raise one pound of water through one degree Fahrenheit. Approximately 143 B.t.u’s. are required to convert one pound of ice into water. 180 B.t.u’s. are required to raise one pound of water front its freezing point (32°F.) to its boiling point (212°F.). Approximately 970 B.t.u’s. are required to convert one pound of water from a liquid at its boiling point (212°F.) into steam.
One gallon of water will absorb approximately 1350 B.t.u.’s. if raised from 50°F. to 212°F. This same gallon of water will absorb approximately 8,080 more B.t.u’s. if it is converted into steam. Herein lies the secret of the successful employment of water as a fire extinguishing agent. That part of the water which is not converted into steam when introduced into the zone of combustion has not been fully utilized. That part which is converted into steam has not only absorbed heat to its capacity but within a confined space contributes to extinguishment through the process of oxygen dilution. One cubic, foot of water if converted into steam will produce seventeen hundred cubic feet of steam.
Official U. S. Coast Guard Photo
One 2 1/2 inch low velocity fog head used in these demonstrations delivers approximately 114 gallons of water per minute. This is equal to approximately 15 cubic feet of water. If full steam conversion is obtained, approximately 25,000 cubic feet of steam will be produced in one minute. This 114 gallons of water will absorb approximately 1,000,000 B.t.u’s. or the number of B.t.u’s. which are generated bv the burning of approximately seven gallons of bunker oil if complete combustion is attained.
In these demonstrations the primary extinguishing action is that of heat absorption. The secondary extinguishing action is that of oxygen dilution within the machinery space. It is believed that the uniform cooling of the heated steel effected within the space is due to the water, in the form of mist, being carried thioughout the space by convectional currents which are developed as the cooling progresses.
During the period from Aug. 31 to Dec. 21 of last year, an interesting and far reaching series of experimental fires were conducted at the Fort McHenry Training Station, Baltimore, Maryland. An unseaworthy Liberty Ship the “Gaspar de Portola” has served as the test laboratory. This vessel was obtained from the War Shipping Administration by Vice Admiral Waesche, Commandant of the Coast Guard. It was berthed at Fort McHenry last July. Commander Layman was authorized to conduct experimental fires within the machinery space to determine the most practical and effective methods of controlling and extinguishing fires of this type, also to make a study of temperatures which are developed within the machinery space and the period of time required to produce critical temperatures in adjoining holds and compartments.
The “Gaspar de Portola” is a standard cargo ship, 441 feet in length with a beam of 57 feet. The machinery space is a combined engine and fire room. It contains the steam generating plant and the propulsion and pumping machinery. This space occupies the entire midship section of the ship.
It is approximately 50 feet in length and 56 feet wide at the bottom (the floor plate level). The superstructure of the ship forms the upper section of this space. The depth from the main deck is approximately 32 feet.
Under the floor plate level is a space from two to three feet in depth. This space is known as the bilge. Into this space will flow any liquid which is released within the machinery space. The bilge will contain about 30,000 gallons of liquid if the ship is on an even keel without raising the liquid above the floor plates. If there is a release of oil within the machinery space it will flow into the bilge and will extend over a surface area ot approximately 1.800 square feet.
A part of this surface is in open spaces around the machinery foundations, valves, and manifolds. The remainder is under the steel floor plates. About one-third of the oil surface w’ill be in the open spaces and two-thirds concealed beneath the floor plates.
There are many pipes and other obstructions located within the bilge which prevent complete coverage of the oil surface by applying foam at any one point.
Located in each corner of the forward section is a fuel oil settling tank. Each of these containers has a capacity of 14,083 gallons. Two boiler foundations are located between the settling tanks. The boilers have been removed, and the boiler foundation spaces have been made liquid tight. These spaces were used as oil burning tanks during the preliminary test fires.
Preparations for Tests
On completion of the preliminary tests, these spaces were covered with steel plates. The opening in the smoke stack has been closed in order to simulate conditions which would exist if the boilers were in place. The main entrance to the machinery space is by a door from the main deck, aft passage. A series of sloping steel ladders and platforms extend from this opening to the floor plate level. Located at various levels within the machinery space are pipes, gratings, and other obstructions. At the second deck level, on the port side in the aft corner is located a small storeroom, known as the Engineer’s Storeroom, and directly below on the next level is another small storeroom. The side of these storerooms next to the machinery space is open and is covered with heavy wire. Some Class “A” materials will be stored in these spaces. On the starboard side about 8 feet above the floor plate level and extending along the aft bulkhead is a platform on which is mounted the electrical equipment. The floor of the machinery space is approximately 12 feet beneath the water level.
Adjoining the machinery space, fore and aft, are cargo spaces. These spaces are separated from the machinery space by water-tight, steel bulkheads. A major fire within the machinery space if not controlled promptly may cause sufficient heat to be transmitted throught uninsulated sections of these bulkheads to involve cargo or other combustible materials in the cargo spaces.
We have found that in order to extinguish a major oil fire within the machinery space, it is necessary to control the entry of air from the outside atmosphere. To this end, consideration must be given to the air intake openings. There are four doors into the machinery space; one from the boat deck, two from the main deck, and one from the shaft tunnel. There are six main ventilators. These are circular metal tubes which extend from above the superstructure to within 8 to 12 feet of the floor plates. Two are located near the forward bulkhead, two midship, and two near the aft bulkhead. They are evenly spaced in order to allow cool air from the outside atmosphere to be uniformly distributed at the floor plate level. There is an opening 3j4 x 3 feet in size from the second deck passage, port side, to the Engineer’s Storeroom. It is covered by a heavy wire grill. This is a major air intake during a fire in the machinery space. The skylight openings and the two ventilators located on top of the skylight house complete what may be termed the true air intake openings. The only other opening into the space is the space between the smoke stack and the stack casing. This space provides an insulation for the smoke stack and an exhaust opening through which heated air can escape from the machinery space.
Commander Lloyd Layman, in charge of fire protection training for the U. S. Coast Guard, conducted a series of eleven tests in fire extinguishment aboard a salvaged Liberty ship at Fort McHenry, Maryland. These tests were run during the period of August 31 to December 21 last year.
Commander Layman has made available to FIRE ENGINEERING reports of the entire series, together with other data, including a large number of photographs. From this most unusual collection of information an article has been prepared for publication in this journal. The first installment appears herewith; the second will be published in the March issue.
The article deserves careful study because of the bearing the techniques of fire fighting developed by these tests may have on municipal fire suppression strategy.
Official U.S. Coast Guard Photo
Combustible materials within the machinery space are bunker, lubricating, and cylinder oils and a limited quantity of Class “A” materials. A release of bunker oil is the major fire hazard. A broken pipe or a punctured settling tank may release considerable volume of bunker oil. There are three grades of bunker oils used as fuel in commercial, steam-driven, cargo ships. They arc bunker oil ‘‘A’’, “B”, and “C”. Bunker “C” is the most commonly used. It is a very heavy oil which must be preheated before it can be used as boiler fuel. Bunker “A” is a lighter oil which has a much lower pour point and is usually used by ships operating in very cold climates. Navy Special fuel oil is used by the steam driven ship of the Navy and Coast Guard. Its specifications are very simular to those for bunker “A”. It has a slightly lower pour point. In the test fires, we have used either bunker “A” or a mixture of bunker “A” and Navy Special. Bunker “A” and Navy Special are more difficult to extinguish than either bunker “B” or “C”. By using bunker “A” and replacing the oil consumed in each test fire with Navy Special, it has been possible to keep the test oil very close to the specifications of bunker “A”. In the preliminary test fires, from 1,000 to 2,000 gallons of bunker “A” oil were placed in the boiler foundation spaces. For Test Fire No. 5—5,000 gallons of bunker “A” oil were released in the bilge. This provided an oil depth of approximately 4’/2 inches extending over about 1,800 square feet. After each test fire, the oil depth is measured and an estimate is made of the number of gallons consumed. Before the next test, the estimated number of gallons consumed in the previous fire is replaced with Navy Special fuel oil. The usual amount is 1,000 gallons.
Thermocouples Record Temperatures
An electronic pyrometer together with eleven thermocouples were installed previous to Test Fire No. 5. The thermocouple terminals are located at various points throughout the machinery space. It is possible to determine the degree of temperature at points three feet above the floor plates and at all overheads within the space. By pressing a station control button on the pyrometer, the temperature at any one of the eleven locations ishown on the dial. Temperature reading at all locations are recorded each minute during test fires.
Carbon Dioxide System Provided.
This ship is provided with a carbon dioxide system for the machinery space. The system has 29-50 pound carbon dioxide cylinders, a total of 1,450 pounds of gas. The gas outlets are located at various points under the floor plates. The entire volume of gas is discharged into the machinery space in a period of two to three minutes after the release control is pulled. The carbon dioxide system has been used in several test fit es.
The success or failure of the carbon dioxide system in extinguishing a major oil fire within the space will depend upon a number of factors. The major factor is the period of time the fire has burned before the carbon dioxide is discharged into the space. It would be very difficult if not impossible to determine the exact number of minutes after ignition of a fire that this system would be effective. Other than the closing of the doors, there is no mechanical means of restricting the flow of air into the space from the outside atmosphere. For the carbon dioxide system to be effective, it is suggested that the crew evacuated the machinery space promptly, close all doors, and release the system without any unnecessary delay. In a ship with the boilers in operation, the effective period may not exceed ten minutes.
Eleven experimental fires were conducted within the machinery space. The first four were preliminary in which the boiler foundation spaces were used as burning tanks. From these preliminary fires, it was able to determine the air intake openings and the means of closing these openings. The burning surface in the preliminary test fires did not exceed 346 square feet. With the oil released in the bilge, the burning surface was increased to approximately 1,800 square feet. In the preliminary test fires, the boiler foundation spaces formed tank like containers. The air had to enter from the sides and free burning did not extend to the center part of the surface. A considerable volume of smoke was given off fluring these fires. With the oil located jn the bilge, air is distributed over the entire surface and the burning at all points appears to be fairly uniform after the fire has burned from fifteen to twenty minutes. As the degree of temperatures increases within the space, there is an increase in the volume of air drawn into the space through the air intake openings. The smoke decreases in volume and changes in color from black to brown and gray.
Test No. I
I. TIME-
Afternoon of 31 August, 1944.
II. PURPOSES-
1.Primary purpose to determine under fire conditions: (1) the openings through which air can enter the engineroom; (2) the relative volume and direction of air flow; (3) if extinguishment could be accomplished solely by closing of air intake openings.
2 Secondary purpose: (1) to determine the probability of a smoke explosion; (2) the practicability of using the shaft tunnel and opening in the bulkhead between the shaft tunnel and the engineroom as an avenue of attack.
III. CONDITIONS BEFORE TEST-
1. No changes were made in the engineroom space which would favor a fire-fighting party; with the following exceptions this space was kept in its normal condition.
a. Both boilers have been removed and the smoke stack closed with steel plate. The space between the stack and stack casing left unchanged.
b. The boiler foundation spaces were made liquid tight and covered with removable plates to make these spaces available as containers for the fuel oil used during tests.
2. Two 3 inch hose lines were laid from a 500 gallon skid-pump unit, located on the adjacent pier, to the main deck. Two 1 1/2 inch lines with allpurpose nozzles were placed down the forward escape hatch to the shaft tunnel and a number of stand-by lines located at various strategic points on the main deck.
3. One thousand gallons of Bunker “A” fuel oil was placed in the port boiler foundation space and the cover plates removed from the starboard half of this space leaving an opening of approximately 86 sq. ft. uncovered during the test.
IV. TEST RECORD-
1. Using about one gallon of gasoline to prime the oil, the fire was started at 1517 o’clock after which the fire party remained in the engineroom without physical discomfort for approximately five minutes before the smoke banked down to near the floor plate level. Very little radiant heat was given off by the fire.
2. From topside it was noted that almost immediately after ignition, black smoke started to come from the space between the stack and stack casing and from the forward port ventilator. The flow of air was downward in all main ventilators with this one exception.
3. After the fire had continued for fifteen minutes canvas covers were placed on all main ventilators except the forward port. Smoke ceased to come from this ventilator and the flow of air changed to . downward. This ventilator was then covered and within a few minutes the smoke emitting from the stack casing decreased in volume and density.
4. Covers were placed on the two small ventilators located over the skylight when an indraft of air was noted. The skylight openings remained closed during the test. Twenty minutes after ignition of the oil all ventilators had been closed.
5. Up to this time considerable air had been entering the engineroom through the grilled opening between the Engineer’s Storeroom and the second deck passage on the port side. The indraft of air increased considerably when all topside ventilators were covered. This opening was covered thirty minutes after the oil was ignited (1547) and within a few minutes the smoke coming from the stack casing decreased in volume and changed from black to gray.
6. Forty-five minutes after the oil was ignited only a small amount of light gray smoke was being emitted from the stack casing.
7. Fifty-five minutes alter the oil was ignited the two aft main ventilators and the two small ventilators located over the skylight were uncovered to prelude any possibility of a smoke explosion occurring when the fire-fighting party entered the engineroom. After these ventilators were uncovered the smoke coming from the stack casing changed to black in color and increased greatly in volume.
8. One hour after the oil was ignited a two man fire-fighting party entered the engineroom through the opening front the shaft tunnel. Although the fire was located in the most inaccessible position from the point of entry and considerable smoke and heat were preseni, the fire-fighting party was able to advance within striking distance of the fire by keeping close to the floor plates. No respiratory protection was used by members of this party.
9. The burning oil was completely extinguished and the heated steel in the immediate vicinity was cooled by the use of high velocity fog from a single 1 1/2 inch all-purpose nozzle. It was necessary to use the solid stream from the all-purpose nozzle to reach the burning insulation on the degaussing cable located in the overhead on the port side. It took approximately five minutes to completely’ extinguish all fire and to cool the heated steel to prevent reignition of the oil. The amount of water used was approximately 200 gallons.
V. CONDITION AFTER TEST-
1. Damage from the fire within the engineroom w’as surprisingly small as will be noted in the following observations:
a. There was considerable warping of the sides of the fuel oil container. Angle iron cover plate supports were warped and some broken in the uncovered section. The section of cover plates next to the open space was warped.
b. Paint did not flash. The paint blistered and charred on all horizontal and vertical surfaces where heated smoke collected or moved upward in the overhead. No blistering or charring of paint was noted on surfaces up to twelve feet above the floor plates except on fhe two forward main ventilators.
c. Practically all surfaces at upper levels were coated with carbon.
d. Grease on the machinery did not melt, flow, or ignite.
e. The only apparent burning of material other than the fuel oil was the insulation on a short section of the degaussing cable located in the overhead on the port side
f. The paint on the upper half of the aft bulkhead on the port side of No. 3 hold was discolored and blistered. This surface gave off some smoke during the fire.
g. Combustible materials located in the second deck section, directly over the engineroom, showed no indications of charring and none w’ere ignited. The deck of the port side passage, second deck, did develop a slight warp.
2. By measuring the level of the oil before ignition and after the removal of water following the test it was estimated that approximately 225 gallons of oil had been consumed.
VI. TENTATIVE Conclusions—
1. Fires occurring within the enginerooms of steam driven ships may appear to be more hazardous, to individuals not familiar with the fundamentals involved, than the facts justify. The basis of this misconception is the large volume of black smoke emitted from the engineroom. When bunker oils burn they produce a considerable volume of black smoke. The volume of smoke is greatly increased when the flow of air into the zone of combustion is restricted.
2. The shaft tunnel and the opening in the bulkhead between the shaft tunnel and the engineroom provide an effective avenue of attack on the level of the fire. When the door to the engineroom is opened there is a strong indraft of air which drives all flame and smoke from the shaft recess toward the interior of the engineroom.
3. Trained fire-fighting personnel thoroughly acquainted with this type of ship can enter the engineroom by way of the shaft tunnel and extinguish a major tire. If the fire is attacked promptly extinguishment can be effected with a small volume of water and with little damage to the ship. During the early stage of a fire, the fire-fighting personnel could advance to any position within the engineroom without being seriously handicapped by either smoke or heat.
4. The possibility’ of a smoke explosion occurring within an engineroom, upon admission of air, after all air intakes have been closed for a period of time, is believed to be eliminated by the presence of the opening between the smoke stack and the stack casing. This opening is located at the highest level within the space and provides a natural outlet for the continuous escape of a major part of the heated smoke.
Test No. 2
I. TIME-
27 September, 1944.
II. PURPOSES-
1. The primary purpose: to determine the effectiveness of the carbon dioxide extinguishing system under the following conditions:
a. With the ventilators and other air intake openings uncovered.
b. Failure to release the carbon dioxide promptly after a major fire had developed within the engineroom. The delay interval to be twenty minutes.
2. Secondary purpose: to determine
the advisability’ of applying water fog from the door openings on the main deck to reduce the’ temperature within the engineroom previous to the entry of the fire-fighting party’ from the shaft tunnel.
III. CONDITIONS BEFORE TEST-
1. The engineroom remained the same as reported after the initial fire test of 31 August, 1944 with the following exceptions :
a. Both boiler foundation spaces were used as fuel oil containers and all but two rows of cover plates were removed, leaving approximately’ 109 sq. ft. of each tank uncovered during the test. The total burning surface was 346 sq. ft.
b. Approximately 900 gallons of bunker “A” fuel oil was placed in each container.
- 2. Two 3 inch hose lines were laid from a 500 gallon skid-pump unit, located on the pier, to the main deck to supply the 1 1/2 inch hose lines. Two 1 1/2 inch lines with all-purpose nozzles were placed down the forward escape hatch to the shaft tunnel. Two 1 1/2 inch lines were laid to the starboard passage door of the engineroom on the main deck. One 1 1/2 inch line was laid to the main engineroom entrance.
- TEST RECORD—
1. Using gasoline to prime the oil, fire was started at 1117 after which the fire party remained in the engineroom without physical discomfort for about six minutes before the smoke banked down to near the floor plate level.
2. From the topside, it was noted that almost immediately after ignition, black smoke started to come from the space between the stack and the stack casing, the open skylights, the two small ventilators located over the skylight, and from the forward starboard ventilator. The flow of air was downward in all main ventilators with this one exception.
- 3. Twenty-one minutes after the oil was ignited the carbon dioxide system was discharged into the engineroom. Within one minute the smoke emitting decreased in volume and changed to gray in color. Three minutes after the system was discharged the smoke was increasing and changing to black in color. Four minutes after discharging the system the volume, density, and color of smoke was the same as before the carbon dioxide was released.
- 4. Thirty minutes after the start of test, water fog was applied from two 1 1/2 inch all-purpose nozzles from the door opening at the forward end of the starboard passage on the main deck and from one 1 1/2 inch all-purpose nozzle at the main engineroom entrance. Within one minute the smoke started to decrease in volume and change to gray in color. Water fog was applied for ten minutes at these locations during which time there was a constant diminishing of the quantity and density of smoke with steam being apparent at the end of this period.
Official U. S. Coast Guard Photo
5. Forty minutes after start of test two fire-fighting parties, each consisting of two men, entered the engineroom from the shaft tunnel and applied high velocity water fog from two 1 1/2 inch nozzles. Six minutes after these parties entered the engineroom the fire was completely extinguished.
6. It was necessary to discontinue the use of water fog from the door openings on the main deck after the firefighting party entered the engineroom. Application of water fog from the door opening near the forward end of the starboard passage had a tendency to restrict the flow of smoke and steam from the engineroom by way of the opening between the stack and stack casing. The application of water fog from the main engineroom entrance allowed heated water, almost at the boiling point, to fall on the members of the fire-fighting party.
7. The fire-fighting party operated without respiratory protection. Tests made with a flame safety lamp indicated no deficiency of oxygen when the firefighting party entered the engineroom.
8. Approximately 1,600 gallons of water was applied from the door openings on the main deck. Approximately 300 gallons of water was used by the fire-fighting party to extinguish the fire.
V. CONDITIONS AFTER TEST-
1. The engineroom was in practically the same condition as reported after test fire No. 1 (31 August, 1944), with the following changes:
a. The paint at all levels was blistered and, at some locations, completely removed.
b. The paint on the upper half of the aft bulkhead in No. 3 hold was discolored and blistered. There was considerable warping of the plates of this bulkhead.
c. Grease on machinery flowed but did not ignite.
d. Solder on joints of wire at electrical equipment platform level was melted.
e. No burning of Class A material was apparent.
f. There was considerable discoloration and peeling off of paint on the exterior of the stack casing on the topside.
2. By measuring the level of the oil before ignition and after removal of
water following the test it was estimated that approximately 350 gallons of oil had been consumed.
VI. TENTATIVE Conclusions—
1. The delay of twenty-one minutes is a sufficient period of time to heat the sttel in the vicinity of the burning oil to a temperature greater than the ignition temperature of the oil. This factor permits reignition of the oil.
2. To maintain an oxygen dilution within an engineroom, under similar conditions, it is necessary to restrict the flow of air from the outside atmosphere.
Remarks—The carbon dioxide system provides a total of 1,450 pounds of gas. When a volume of carbon dioxide gas is released into a heated space an expansion of the gas takes place due to its rise in temperature. Its specific gravity is reduced in ratio to that of the cool air entering from the outside atmosphere. Due to this factor a part of the carbon dioxide gas escapes with the out-flow of heated smoke. If the flow of air from the outside atmosphere is not restricted, under these conditions, the dilution of carbon dioxide gas will be sufficient to allow reignition.
3. The application of water fog from the openings on the main deck reduced the temperature within the engineroom. The fire-fighting party was able to operate with less physical discomfort than in test fire No. 1.
4. The application of water fog from the opening on the main deck should be discontinued when the fire-fighting party enters the engineroom from the shaft tunnel.
Test No. 3
I TIME-
On October 9, 1944 two additional test fires were conducted.
II Purposes—
1. Purpose of Test Fire No. 3: To determine the effectiveness of the carbon dioxide extinguishing system under the following conditions: hatch to the shaft tunnel. Two 1 1/2 inch lines were laid to the main engineroom entrance. One 1 1/2 inch line was laid to the starboard passage door of the engineroom on the main deck.
a. With the ventilators and other air intake openings uncovered.
b. With prompt release of the carbon dioxide after a major fire had developed within the engineroom. The time interval between start of fire and release of carbon dioxide to be ten minutes.
2.Purpose of Test Fire No. 4 (which was started one hour after Test Fire No. 3): To determine if prompt extinguishment and cooling of the heated metal to below the ignition temperature of the oil could be effected by closing the air intake openings and applying water fog through door operings on the main deck.
CONDITIONS BEFORE TEST-
1. The engineroom remained the same as reported after Test Fire No. 2 (27 September, 1944) with the following exceptions.
a. Approximately 700 gallons of bunker “A” fuel oil was located in each boiler foundation space with a total burning surface of 346 sq. ft.
b. Two 3 inch hose lines were laid from a 500 gallons skid pump unit located on the pier, to the main deck to supply the 1 1/2 inch hose lines equipped with all-purpose placed down the forward escape nozzles. Two 1 1/2 inch lines were
TEST RECORD-
1. Using gasoline to prime the oil fire was started at 1405, after which the fire party remained in the engineroom without physical discomfort for about five minutes before the smoke banked down to near the floor plate level.
2. From the topside, it was noted that almost immediately after ignition, black smoke started to come from the stack casing, the open skylights, and forward starboard ventilator. The flow of air was downward in all main ventilators with this one exception.
3. Ten minutes after the oil was ignited the carbon dioxide system was released. Within one minute the smoke emitting decreased in volume and changed to gray in color. During the ten minutes following the release of the carbon dioxide smoke continued to decrease in volume and change to lighter gray in color. Twenty-three minutes after release of the carbon dioxide smoke had ceased to come from the stack casing, the open sklyights, and the ventilators.
official U. S. Coast Guard Photo
4. Forty-five minutes after oil was ignited a fire party entered the engineroom from the shaft tunnel. A lighted flame safety lamp placed on the electrical equipment platform (7 ft. 6 inches above the floor plates) before ignition of oil, was found extinguished. Open flame lowered to the oil level in the boiler foundation space continued to burn. Carbon was found burning in the inside of the port boiler foundation space.
Test No. 4
1. Using gasoline to. prime the oil remaining in the boiler foundation spaces after Test Fire No. 3, fire was started at 1505, after which the fire party remained in the engineroom without physical discomfort for about five minutes before the smoke banked down to near the floor plate level.
(Continued on page 110)
Coast Guard Fire Tests
(Continued from page 96)
2. From the topside, it was noted that almost immediately after ignition, black smoke started to come from the space between the stack and the stack casing, the Open skylights, and the forward starboard and the midship port ventilators. The flow of air was downward in all main ventilators with these two exceptions.
3. Six minutes after start of test, dense black smoke was emitting from the openings on topside with the exception of the forward starboard and midship port ventilators. The flow of air at the open skylights was alternating from inward to outward at about one second intervals.
4. F’ifteen minutes after start of test, dense black smoke was emitting from the stack casing, the two forward and midship port main ventilators. Flow of air was downward in remaining three main ventilators and in the open skylights.
5. Thirty-one minutes after start of test, the grilled opening between the Engineer’s Storeroom and second deck port side passage was covered. During the following five minutes the aft port and starboard, and the midship starboard main ventilators were covered.
6. Thirty-nine minutes after start of test, the smoke began to decrease in volume and change to gray in color.
7. Forty-one minutes after start of test, the skylight house, including the two small ventilators on top, was covered with a canvas hatch cover. A small amount of gray smoke was emitting from stack casing.
8. Forty-three minutes after start of test, the two forward and the midship port main ventilators were covered. Very small amount of light gray smoke was emitting from the stack casing. Fifty-three minutes after start of test an extremely small amount of light gray and light brown smoke was emitting from the stack casing.
9. Fifty-five minutes after start of
test, the main engineroom door was opened and high velocity water fog applied from two 1 1/2 inch all purpose nozzles. Smoke continued to diminish in volume with steam apparent.
10. Sixty-two minutes after start of test, highvelocity water fog was applied from one 1 1/2 inch all-purpose nozzle at the starboard passage door on the main deck. Very small amount of white, and light brown smoke emitting.
11. Sixty-four minutes after start of test one nozzle at main door of engineroom was shut off. Smoke continued to diminish in volume and density.
12. Sixty-five minutes after start of test, remaining nozzles were shut off. Extremely small amount of light vapors were emitting.
13. Seventy minutes after start of test, covers were removed from all openings.
14. Seventy-five minutes after start of test a fire party entered engineroom by way of shaft tunnel. Fire was found to have been extinguished and very little smoke present. Fire party w»as able to proceed in an upright position to any point at the floor level without physical discomfort.
15. Seventy-eight minutes after start of test, no smoke or vapors were emitting. During the later half of this test, considerable smoke was being given off by the plywood covering on the aft bulkhead in the Officers’ Mess. After fire was extinguished in the engineroom. part of this plywood was removed and a small amount of burning wood located. Fire was extinguished wdth a few gallons of water from one 1 1/2 inch allpurpose nozzle.
16. Heat indicating lacquer painted on the aft bulkhead in No. 3 hold indicated a temperature of 250° F. was reached down to within 7 feet from the engineroom floor plate level. 500° F. was reached down to within 12 feet. No spot on this bulkhead reached 1000° F. The forward surface (15 inches from bulkhead) of a vertical “I” beam bulkhead stiffener did not reach 250° F. at any point. The stiffener selected was located at the hottest part of the bulkhead.
V CONDITIONS AFTER TEST-
1. The engineroom was in practically the same condition as reported after test Fire No. 2 (27 September, 1944) with the following changes and remarks:
a. There was considerable melting of solder on joints of electrical wires.
b. Grease on machinery flowed but did not ignite.
c. No burning of Class A material was apparent.
d. All surfaces in Engineer’s Storeroom coated with carbon.
VI TENTATIVE CONCLUSIONS-
1. If the carbon dioxide is released promptly after a major fire has started within the engineroom the volume of carbon dioxide delivered by this system is sufficient to extinguish the fire and prevent reignition.
Remarks: It is believed that the governing factor in the success or failure of a carbon dioxide system is dependent upon the degree of heat attained by the metal located in the immediate vicinity of the fuel. If the metal has been allowed to reach a temperature greater than the ignition temperature of the oil, reignition may occur.
Editor’s Note: See the March issue for second installment of Commander Layman’s tests.
