Division B
Acceptable Solutions
Part 6 — Fire Protection Equipment
Section 6.4. Water-Based Fire Protection Systems
6.4.1. General
6.4.1.1. Inspection, Testing and Maintenance
1) 
Water-based fire protection systems shall be inspected, tested and maintained in conformance with NFPA 25, “Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.” (See Appendix A.)
Water-based fire protection systems shall be inspected, tested and maintained in conformance with NFPA 25, “Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.” (See Appendix A.) 6.4.2. Standard Fire Hose Thread
6.4.2.1. Specifications
1) All 2-1/2-inch fire hose couplings and allied fittings shall have a 60° truncated
vee thread having dimensions in inches for the male and female couplings as set out
in Table 6.4.2.1.
| Table 6.4.2.1. Thread Dimensions Forming part of Sentence 6.4.2.1.(1) | |||||||||
| MALE | |||||||||
| Nominal Inside Diameter | Thread Per Inch | Major Diameter | Pitch Diameter | Minor Diameter | Pitch | Depth of Thread | |||
| Max | Min | Max | Min | Max | Min | ||||
| 2.500 | 8 | 3.000 | 2.990 | 2.919 | 2.909 | 2.838 | — | 0.125 | 0.081 |
| FEMALE | |||||||||
| Nominal Inside Diameter | Thread Per Inch | Major Diameter | Pitch Diameter | Minor Diameter | Pitch | Depth of Thread | |||
| Max | Min | Max | Min | Max | Min | ||||
| 2.500 | 8 | — | 3.020 | 2.949 | 2.939 | 2.868 | — | 0.125 | 0.081 |
2) All 2-1/2-inch fire-hose couplings shall be made with the higbee cut
to aid quick coupling, the design of which requires the female swivel to have a
distance from the face of the coupling swivel to the start of the first thread of
1/16 of an inch, and the male thread shall have a distance from the face of the
nipple to the start of the first thread of 1/8 of an inch.
3) Thread form shall be calculated as follows:
N= number of threads per inch
P= pitch of thread
D= depth of thread
F= flat or truncation of thread
4) The threaded portion of the 2 1/2-inch female hose coupling shall be shorter than
the threaded portion of the male by 1/32 of an inch for end clearance, and the outer
edge of the male pilot end and the inside edge of the female end shall be slightly
chamfered.
5) The length of the female hose-coupling shall not be less than 3 31/64 inches.
6) The threaded end of the female coupling, including the washer recess, shall be
28/32 of an inch in length.
7) The length of the male hose-coupling shall not be less than 3 3/32 inches.
8) The threaded end of the male coupling shall be 29/32 of an inch in length.
9) Material from which fire-hose couplings and fittings are fabricated shall be suitable
for their intended use.
10) The outside diameter of the female coupling shall not be less than 3 5/8 inches
for the fixed portion and 3 11/16 inches for the swivel portion.
11) The outside diameter of the male coupling shall not be less than 3 5/8 inches.
12) Rubber washers which are made to fit the standard female coupling shall be 3 1/4
inches outside diameter, 2 9/16 inches inside diameter, and 1 1/4 inches in
thickness.
13) Fire-hydrant operating spindle-nuts and port cap-nuts shall be pentagonal in shape
and their dimensions as follows:
a) diameter of the outside circumscribed circle shall be 1 3/4 inches;
b) the nut shall measure not more than 1 1/4 inches in height.