(a) Piping, fittings, and valves must be:

1. (1) In accordance with the manufacturer's approved design, installation, operation, and maintenance manual;
2. (2) Securely supported and when necessary protected against damage;
3. (3) Protected inside and out against corrosion; and

4. (4) Equipped with:

   1. (i) Dead end lines (dirt traps) that extend at least 2 inches beyond the last nozzle of each distribution line and that are closed with a cap or plug; and
   2. (ii) Drains and dirt traps, fitted where necessary to prevent dirt or moisture accumulation and located in accessible locations where possible.

(b) Piping requirements. Piping must be:

1. (1) Used exclusively for extinguishing system purposes;
2. (2) Protected by a pressure relief valve in sections where gas pressure can be trapped between closed valves; and
3. (3) Welded if it passes through living quarters.

(c) Piping prohibitions. Piping must not:

1. (1) Use rolled groove or cut groove ends; or
2. (2) Be fitted with drains or other openings if it passes through living quarters.

(d) Valve requirements. Valves for system operation must be:

1. (1) Outside the protected space, and
2. (2) Marked, if serving a branch line, to indicate the space the branch line serves.