[Code of Federal Regulations] [Title 46, Volume 4] [Revised as of October 1, 2006] From the U.S. Government Printing Office via GPO Access [CITE: 46CFR108.409] [Page 133] TITLE 46_SHIPPING (This book contains parts 90 to 139) CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PART 108_DESIGN AND EQUIPMENT--Table of Contents Subpart D_Fire Extinguishing Systems Sec. 108.409 Location and spacing of tubing in pneumatic fire detection system. (a) All tubing in a pneumatic fire detection system must be on the overhead or within 300 millimeters (12 inches) of the overhead on a bulkhead in a location where-- (1) No portion of the overhead is more than 3.6 meters (12 feet) from the nearest point of tubing; (2) Beams or girders extending below the ceiling or other obstructions do not detract from the effectiveness of the tubing; and (3) Damage to the tubing, is unlikely to occur if it is not protected. (b) If tubing in a tubing circuit is installed in an enclosed space, at least 5% of the tubing in the circuit must be exposed in the space, except that at least 7.6 meters (25 feet) of tubing must always be exposed in the space. (c) A pneumatic fire detection system must be set to activate after approximately a 22[deg]C. (40[deg]F.) per minute increase in temperature at the center of the circuit in the system.