FIRE BARRIER TEST on FBS^® System-ELECTRICAL CONDUIT

A 4” fiberglass electrical conduit, filled with a combination of power, control, and instrumentation cables was instrumented with thermocouples, covered with Flame Seal Products “FBS-60 Protective System”, and tested in accordance with ASTM E119-98 Standard Test Methods for Fire Tests of Building Construction and Materials. Under the test conditions described, the system evaluated successfully protected the conduit test article for a fire resistance period of 60 minutes.
 

                    Reviewed and approved:

INTRODUCTION

The protection of vital electrical circuits from the effects of an external fire exposure is of primary concern in the design and construction of an electrical power generating plant. Typical “fire protective envelopes” are designed to protect the contents of an electrical raceway for fire exposure periods of one to three hours.

The external fire exposure selected to evaluate this protective envelope system is that described in the ASTM E119-98 Fire Tests of Building Construction and Materials (E119 Time-Temperature Curve, described later in this document.)

Typical fire test programs involve the selection and construction of a specific electrical raceway system, instrumentation for thermal measurements, followed by the application of the fire resistive barrier system by qualified personnel.

This standard should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or risk of materials, products, or assemblies under actual fire conditions. However, results of this test my be used as elements of a fire risk assessment that takes into account all the factors that are pertinent to an assessment of the fire hazard of a particular end use.

TEST PROCEDURE

The test furnace used consists of a large horizontal exposure chamber, with internal dimensions of 12 ft (length) by aft (width). The furnace is equipped with diffuse-flame propane gas burners symmetrically located across the floor of the furnace and controlled by individual gas flow valves, with the overall gas flow to valves, with the overall gas flow to the furnace being controlled by a single gas control valve. Capable of a maximum heat output of 5 million Btu/hour, these burners are arranged well below the exposed face of the specimen to ensure an even temperature at the surface of the specimen. Windows are located on two sides of the furnace to allow observation of the specimen during fire exposure. The depth of the furnace is variable, being increased to the desired amount by the addition of concrete blocks around the perimeter ledge. These blocks are lined with ceramic fiber blanket to minimize the heat loss from the furnace and to decrease the time required for the furnace walls to heat up.

The temperature within the furnace is determined to be the mathematical average of thermocouples located symmetrically within the furnace and positioned twelve inches away from the exposed face of the test specimen. The materials used in the construction of these thermocouples are those suggested in the test standard. During the performance of a fire exposure test, the furnace temperatures are monitored at least every 15 seconds and displayed for the furnace operator to allow control along the specified temperature curve.

The fire exposure is controlled to conform with the standard time-temperature curve shown in the table below: 

The fire test is controlled according to the standard time-temperature curves as indicated by average temperature obtained from the readings of the furnace interior thermocouples symmetrically located across the specimen, 12 in. away. The thermocouples are enclosed in protection tubes of such material and dimensions that the time constant of the thermocouple assembly lies between 5.0 and 7.2 minutes, as required by the E 119 standard.  The furnace temperature during a test is controlled such that the area under the time-temperature curve is within 5% of the corresponding area under the standard time-temperature curve for the three-hour test period.

The furnace pressure is controlled to be as nearly neutral with respect to the surrounding laboratory atmosphere as possible, measured at the vertical mid-height of the test specimen.

The fire endurance rating of a fire-resistive barrier system for a specific electrical system component is the maximum time before which one of the following conditions occurs:

               The average temperature of any set of thermocouples for the  electrical system component
               is raised more than 250° F (139° C)  above its initial temperature.

               The temperature of any one thermocouple of the set for each electrical system component
               is raised more than 325°F (181°C) above its initial temperature.
 

Systems reaching either of these criteria, or which are terminated, at times other than even-hour time periods shall be rated to the 15-min increment immediately preceding the time at which the criteria condition or termination occurred.
 

TEST SPECIMEN CONSTRUCTION

A 4” fiberglass electrical conduit (10 ft. long with 1/6 “ wall thickness) was purchased by Flame Seal Products and delivered to the Laboratory. Prior to the installation of the fire protective system, the conduit was filled to an actual cross-sectional fill of 40. 0% with the following mix of cables. All cables were XHHW copper conductors.
 

The protective envelope system was supplied and installed by representatives of  Flame Seal Products, Inc., and the following description of that system was supplied by the client. While complete verification of the system was not possible, since the components were pre-assembled, no obvious deviation from these details was noticed.

The system was a two-layered version of  Flame Seals FBS System. It consisted of the following components:

1) Standard FBS with a 2 mil stainless steel foil outer surface. Dimensions   per piece = 11” x 24” (two pieces per section). Weight = 6.5 lbs. each  (3.55 lbs./sq.ft.).
2) ½ inch thick ceramic wool blanket glued to 2-mil aluminum foil with Flame Seals FX-FBS adhesive. Dimensions per piece=17” by 21 “(one piece per section). Weight=0.35 lbs./sq. ft.
3) 4” wide strips of thin FBS flat stock used at joints, for all butt joints.
4) 3” wide strips of stainless steel foil and fiberglass laminated with FX-FBS adhesive.
5) Stainless steel hog rings, every ½” to ¾” at all joints.
6) Aluminum Tape.
 

Installation was as follows:

A) 4” strips were “coil” wrapped and taped 3 layers thick on 24” centers   located under the joints between sections.
B) Foil faced ½” ceramic wool pieces (#2 above) were wrapped around the  conduit between these joint strips and taped in place with aluminum tape
C)FBS- 60 was located with the ends centered on the joint strips (“A” above), wrapped tightly over the ceramic wool layer and hog ringed in place along all seams formed by junctions between pieces.
D)Butt joints were covered with a 3” wide stainless steel foil and fiberglass laminated and hog-ringed in place.
E) Aluminum tape was installed over the hog-ringed seams.

The completed ten foot long test article was sealed on both ends of the conduit, to stop any heat from escaping, placed on the ledges of a fire resistance furnace which exposed a minimum of 84 inches to the heat. The ledges of the furnace were then built up with concrete block to a minimum of 18 inches above the top of the test article, and an insulated lid was placed on top to complete the furnace assembly.

TEST RESULTS AND OBSERVATIONS

The test item was placed across the Laboratory's intermediate-scale horizontal furnace (as described earlier) and all thermocouples connected to the data acquisition system and their outputs verified. Photographs were taken, the furnace thermocouple positions checked, and the furnace was fired at approximately 2:25 p.m. on March 19, 1999. The ambient temperature was 69 F and the relative humidity was 60%. The furnace pressure was maintained so that the neutral pressure plane was at the vertical mid-height of the specimen. The test procedure was witnessed by Michael Kiser of Flame Seal Products, Inc.

    Observations made during the test are as follows:
 

All temperatures monitored within the test specimen were measured using 24 ga., electrically-welded thermojunctions, Type K Chromel-Alumel, Fiberglass Insulated (Special Limits of Error: +1.1° C) thermocouples, purchased with calibration certifications and lot traceability.

The thermocouple locations can be found in Appendix A.

A summary of the thermocouple data is given in the table below:

                                                      INDIVIDUAL TCs                       AVERAGE  TCs

Listing and plots of the furnace control temperatures and specimen temperatures may be found in Appendix B. A photographic documentation of the test has been included in Appendix C.

CONCLUSIONS

At the end of the 60-minute fire exposure, the highest temperature on the entire test article was 290F. All temperatures remained well below the maximum allowable limits for the entire test duration. The 4” fiberglass electrical raceway protected by Flame Seal Products’ FBS-60 Protective Systems” and evaluated by this Laboratory achieved a rating of 60 minutes.

Flame Seal Products, Inc.                                                                          April 7, 1999  Project No. 14770-104554                                                                       Page 8

Note:  The 4” fiberglass electrical conduit was instrumented with 13 thermocouples along the bottom surface, as indicated. The TCs were mounted on the outside of each rail by covering with a single layer of fiberglass electrical tape. The conduit was loaded with a mixture of power (3/C#6 AWG, 4 pieces), control (7/C#12 AWG, 5 pieces) and instrumentation (4/C#16AWG, 14 pieces) cables to an actual cross-sectional fill of 40%. One cable of each type was instrumented with thermocouples every 6” o/c., attached with a single layer of electrical tape. All cables were then randomly placed into a bundle and pulled through the conduit. All cables were types XHHW with copper conductors.

OMEGA POINT LABORATORIES, INC.  Project No. 14770-104554 FLAME SEAL PRODUCTS, INC. Thermocouple Locations Drawn by :   D.N. Priest   Date:  2/24/99      Scale: 1/2" = 1"

Page 9

Flame Seal Products, Inc.                                                             April 7, 1999 Project No. 14770-104554                                                         APPENDICES

Appendix B

TEST DATA

Page  10

Flame Seal Products, Inc. Project No.  14770-104554 Conduit Surface Temperatures

Page  11

Flame Seal Products, Inc. Project No.  14770-104554 Power Cable Temperatures

Page  12

Flame Seal Products, Inc. Project No.  14770-104554 Control Cable Temperatures

Page 13

Flame Seal Products, Inc. Project No.  14770-104554 Instrumentation Cable Temperatures

Page 14  - Page 31   are  Temperature Measurement Charts at all thermocouple readings shown on graphs illustrated on Pages 10 - 13 -  Available on Request

Page 32

Flame Seal Products, Inc.                                                                                 April 7, 1999 Project No. 14770-104554                                                                             APPENDICES

Appendix C PHOTOGRAPHS

	Page 33
Flame Seal Products, Inc. Project No. 14770-104554	April 7, 1999 APPENDICES
4" Strips taped three layers thick located under joints between sections	Installation of FBS - 60

	Page 34
Flame Seal Products, Inc  Project No. 14770-104554	APRIL 7, 1999 APPENDICES
Aluminum tape installed over scam	4" wide thin FBS flat stock used over all butt joints

	Page 35
Flame Seal Products, Inc.  Project No. 14770-104554	April 7, 1999 APPENDICES
Installation complete except for sealing the ends	Installation complete  (The system evaluated in this report is on the right)

	Page 36
Flame Seal Products, Inc  Project No. 14770-104554	April 7, 1999 APPENDICES
Test item loaded onto furnace (The system evaluated in this report is at the top)	Start of fire exposure

APPENDICES                                    Page 37

Flame Seal Products, Inc.  Project No. 14770-104554

Lid removed after the end of the fire exposure.  (The System Evaluated in this report is at the top)