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Technical Identifying Threads When calipers and O.D. tapes are not available, the following method may be useful. Cut a strip of paper not over 5/8" wide by approximately 18" long. Then wrap the strip tightly around the circumference of the male thread, making sure it is well back against the male shoulder, and the ends overlap. Then pierce once through both layers of the strip with a pin (Fig 1). After removing the strip, mark your pin holes by circling them as shown (or with arrows), to make sure the correct measurement can be taken. The distance between the pin holes, divided by 3.1416 equals the outside diameter of the thread. Next, press your thumb firmly against the threads (Fig. 2) hard enough to make thread impressions on the strip (Fig. 3) thereby giving an impression from which the number of threads per inch can be obtained. NYF New York Fire Dept. Thread 1½" (2.100 ODM x 8 tpi) -- 2½" (3.030 ODM x 8 tpi) CF Chicago Fire Dept. Thread 1½" (1.933 ODM x 11.5 tpi) -- 2½" (2.990 ODM x 7.5 tpi) NYC New York Corporation Thread 1½" (2.093 ODM x 11 tpi) -- 2½" (3.000 ODM x 8 tpi) PERSONAL SPECIAL THREAD TABLE There are well over a hundred special threads in use on fire equipment in the USA. We provide the following table to allow you to chart your special thread requirements for future reference. Please help us better serve you in the future, if you come across a special thread not listed in our chart, please e-mail or fax the thread information to us at sales@dixonvalve.com or 800-283-4966, we will archive it for future reference. Size 1½" 2½" City or Town ODM TPI ODM TPI ODM TPI If you are unable to determine the threads you need: 1) Contact the Fire Department or Fire Marshall responsible for the area where the equipment will be located. 2) Request the threads required for fire hose connections in that area consistent with your requirements. (usually 1½" and 2½") 3) If this fails to get the information you need, contact our Fire Equipment Specialists at 800-355-1991. Always indicate the HOSE THREAD required when ordering! 11-2 Dixon Powhatan 2007
