46 CFR § 108.409 - Location and spacing of tubing in pneumatic fire detection system.

---
identifier: "/us/cfr/t46/s108.409"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 108.409 - Location and spacing of tubing in pneumatic fire detection system."
title_number: 46
title_name: "Shipping"
section_number: "108.409"
section_name: "Location and spacing of tubing in pneumatic fire detection system."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "I-A"
subchapter_name: "A—MOBILE OFFSHORE DRILLING UNITS"
part_number: "108"
part_name: "DESIGN AND EQUIPMENT"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "43 U.S.C. 1333; 46 U.S.C. 3102, 3306; DHS Delegation No. 00170.1, Revision No. 01.4."
regulatory_source: "CGD 73-251, 43 FR 56808, Dec. 4, 1978, unless otherwise noted."
cfr_part: "108"
---


# 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 °C. (40 °F.) per minute increase in temperature at the center of the circuit in the system.