Application Analysis: Providing Fire Protection for the Instrumentation Equipment of an Arleigh Burke Class (DDG) Destroyer
Proposition:
In an effort to increase the fire survivability of a set of sensitive instruments and electronics encased in a metal cabinet aboard Arleigh Burke Class (DDG) Destroyers currently in operation, the United States Navy began searching for an extremely lightweight insulation material that would fit within a specific space allowance and pass a series of prescribed Navy tests to ensure the proper window of safety for the equipment in the event of a high temperature fire on board the vessel.
Primary Goals:
Proposals:
By utilizing a highly specialized form of ThermoDyne’s DynaGuardä Flexible (i.e. Flexible FP) microporous insulation at thicknesses no greater than .50”, a safety window of greater than 15 minutes can be established for the system without providing any additional overall weight to the system or vessel.
Analysis & Testing:
ISO9705
ISO9705 is a complete “burn room” test in which the insulation system and additional hardware are subjected to 200 KW flames which are intended to fully engulf the system. Thermocouples are placed inside the unit to measure the temperature of the inside of the system during testing. Temperature probes are also used outside the unit to ensure that the flame is continuous in temperature and intensity. A United States Navy official is present at the testing to ensure the desired internal temperatures is not exceeded.
Published reports of the procedure listed the following for the unit in which DynaGuardä Flexible FP materials were used:
The Full Scale test of fire engulfing the rack was performed using the room and measurement systems specified in the ISO 9705 Test Procedure. This facility was an 8 x 12 foot fireproof room with a doorway in the center of the nearest 8-foot wall and an 8 foot high ceiling. A 12 inch square sand bed burner was used to produce a 200 KW flame burning 273 CF/Hr of propane. The 18-inch distance of the burner to the bottom of the rack was determined to provide a flame, which fully engulfed the rack.
The test specimen survived the initial 15-minute exposure with no flames or penetration into the interior evident when the fire was removed. A white gas was observed coming from the space between the isolator and the foundation. The gas appeared to be water vapor as it snuffed out a test flame. Following examination, the fire was reestablished and applied for a total of 60 minutes.
At approximately 45 minutes it appeared that there were small flames just beginning to appear at the edge of the insulation jacket. This became a constant flame at 58 minutes. Following the 60 minute exposure, the fire was removed and continuous flames were observed at the edges of the insulation jacket. Five minutes later, the flames were still evident and were then doused with water. Gasses evolving from within the isolator were determined to be flammable.
The Isolation system “passed with flying colors at 15 minutes” and “performed reasonably well at 60 minutes” with the polyurethane remaining contained.”
In an effort to increase the fire survivability of a set of sensitive instruments and electronics encased in a metal cabinet aboard Arleigh Burke Class (DDG) Destroyers currently in operation, the United States Navy began searching for an extremely lightweight insulation material that would fit within a specific space allowance and pass a series of prescribed Navy tests to ensure the proper window of safety for the equipment in the event of a high temperature fire on board the vessel.
Primary Goals:
- The insulation material needs to be relatively lightweight in comparison to metal and heavy traditional cloths in order to add no additional weight to the overall system or vessel.
- The insulation material must be as thin as .080” for some parts of the system, and no thicker than .50” maximum for other parts of the system.
- The insulation material must provide a minimum 15 minute “safety window” for the system in both US Navy test sequences ISO9705 and UL1709 to ensure that internal temperatures inside the unit do not exceed the desired limit (undisclosed).
Proposals:
By utilizing a highly specialized form of ThermoDyne’s DynaGuardä Flexible (i.e. Flexible FP) microporous insulation at thicknesses no greater than .50”, a safety window of greater than 15 minutes can be established for the system without providing any additional overall weight to the system or vessel.
Analysis & Testing:
ISO9705
ISO9705 is a complete “burn room” test in which the insulation system and additional hardware are subjected to 200 KW flames which are intended to fully engulf the system. Thermocouples are placed inside the unit to measure the temperature of the inside of the system during testing. Temperature probes are also used outside the unit to ensure that the flame is continuous in temperature and intensity. A United States Navy official is present at the testing to ensure the desired internal temperatures is not exceeded.
Published reports of the procedure listed the following for the unit in which DynaGuardä Flexible FP materials were used:
The Full Scale test of fire engulfing the rack was performed using the room and measurement systems specified in the ISO 9705 Test Procedure. This facility was an 8 x 12 foot fireproof room with a doorway in the center of the nearest 8-foot wall and an 8 foot high ceiling. A 12 inch square sand bed burner was used to produce a 200 KW flame burning 273 CF/Hr of propane. The 18-inch distance of the burner to the bottom of the rack was determined to provide a flame, which fully engulfed the rack.
The test specimen survived the initial 15-minute exposure with no flames or penetration into the interior evident when the fire was removed. A white gas was observed coming from the space between the isolator and the foundation. The gas appeared to be water vapor as it snuffed out a test flame. Following examination, the fire was reestablished and applied for a total of 60 minutes.
At approximately 45 minutes it appeared that there were small flames just beginning to appear at the edge of the insulation jacket. This became a constant flame at 58 minutes. Following the 60 minute exposure, the fire was removed and continuous flames were observed at the edges of the insulation jacket. Five minutes later, the flames were still evident and were then doused with water. Gasses evolving from within the isolator were determined to be flammable.
The Isolation system “passed with flying colors at 15 minutes” and “performed reasonably well at 60 minutes” with the polyurethane remaining contained.”
UL1709UL1709 is a “hot plate” test in which a 2000°F, 200 KW develops under the system within the first five minutes of the test. Thermocouples are placed inside the unit to measure the temperature of the inside of the system during testing. Temperature probes are also used outside the unit to ensure that the flame is continuous in temperature and intensity. A United States Navy official is present at the testing to ensure the desired internal temperatures is not exceeded.
Published reports of the procedure listed the following for the unit in which DynaGuardä Flexible FP materials were used:
The Full Scale Test of the fire in the space below was performed using a UL 1709 Rapid Temperature Rise Fire test facility, which is normally used for heating sections of structural steel. The total heat flux with this furnace is 204 KW/M2 when it is operating at 2000 Deg F.
The top cover of the furnace was removed and replaced with an adapter plate with a hole, which exposed the bottom of the test specimen to the conditions within the furnace. The furnace was lit and the temperature was made to rise to 1910 deg F within the first 5 minutes and then held near 2050 deg F for the remainder of the test.
The test specimen survived the initial 15 minutes of the exposure with no penetration of the jacket and no ignition of the polyurethane. In fact, the UUT showed little indication of the exposure other than a white nonflammable gas, which was observed coming from the space between the isolator and the foundation. The glowing of the hot metal was also noted. At 22 minutes a polyurethane smell, which continued throughout the test, was first noted. At 30 minutes the visible vapors (smoking) were no longer noted. No other changes were noted until the fire was removed after 62 minutes duration and the slow cool down was watched. The furnace temperature was 760 and 602 deg F 60 and 90 minutes following shutdown.
The Isolation system passed the test with the polyurethane remaining contained both at 15 and 60 minutes exposure.
Published reports of the procedure listed the following for the unit in which DynaGuardä Flexible FP materials were used:
The Full Scale Test of the fire in the space below was performed using a UL 1709 Rapid Temperature Rise Fire test facility, which is normally used for heating sections of structural steel. The total heat flux with this furnace is 204 KW/M2 when it is operating at 2000 Deg F.
The top cover of the furnace was removed and replaced with an adapter plate with a hole, which exposed the bottom of the test specimen to the conditions within the furnace. The furnace was lit and the temperature was made to rise to 1910 deg F within the first 5 minutes and then held near 2050 deg F for the remainder of the test.
The test specimen survived the initial 15 minutes of the exposure with no penetration of the jacket and no ignition of the polyurethane. In fact, the UUT showed little indication of the exposure other than a white nonflammable gas, which was observed coming from the space between the isolator and the foundation. The glowing of the hot metal was also noted. At 22 minutes a polyurethane smell, which continued throughout the test, was first noted. At 30 minutes the visible vapors (smoking) were no longer noted. No other changes were noted until the fire was removed after 62 minutes duration and the slow cool down was watched. The furnace temperature was 760 and 602 deg F 60 and 90 minutes following shutdown.
The Isolation system passed the test with the polyurethane remaining contained both at 15 and 60 minutes exposure.
Results:
Conclusion:
ThermoDyne’s DynaGuard Flexible FP microporous insulation system not only accomplished all of the goals set by the customer, but also substantially exceeded them. As a result, it proved itself to be the best material for the application. For additional information on ThermoDyne’s DynaGuard Flexible FP, or any other ThermoDyne microporous products, please contact ThermoDyne’s team of Applications and Design Engineers at [email protected]
Assumptions:
- ISO9705
- After 15 minutes, it was determined that there was no noticeable deterioration in the insulation material other than soot and the normal indications that it had been exposed to open flame.
- It was further determined that the internal temperature of the system had not exceeded the allowable maximum.
- No toxic off-gassing or unfavorable fumes were detected from the insulation unit.
- In order to completely test the system, the burn was allowed to continue until system failure.
- The internal temperature reached a point that exceeded the allowable maximum only after 45 minutes of continuous burning, thus exceeding the required window of safety by 30 minutes (i.e. 3 times the required duration).
- UL1709
- After 15 minutes, it was determined that there was no noticeable deterioration in the insulation material.
- It was further determined that the internal temperature of the system had not exceeded the allowable maximum.
- No toxic off-gassing or unfavorable fumes were detected from the insulation unit.
- In order to completely test the system, the burn was allowed to continue until system failure.
- The internal temperature reached a point that exceeded the allowable maximum only after 45 minutes of continuous burning, thus exceeding the required window of safety by 30 minutes (i.e. 3 times the required duration).
Conclusion:
ThermoDyne’s DynaGuard Flexible FP microporous insulation system not only accomplished all of the goals set by the customer, but also substantially exceeded them. As a result, it proved itself to be the best material for the application. For additional information on ThermoDyne’s DynaGuard Flexible FP, or any other ThermoDyne microporous products, please contact ThermoDyne’s team of Applications and Design Engineers at [email protected]
Assumptions:
- Graphic of DDG Destroyer courtesy of the United States Navy (http://www.chinfo.navy.mil/navpalib/factfile/ships/ship-dd.html)
- Additional graphics and information taken on-site or provided through strategic partners