After conducting the annual test of a dry barrel hydrant, what is the maximum length of time permitted for full drainage to take place?

According to NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, the procedure for annual hydrant testing requires a verification check for drainage. The standard mandates that the inspector shall check the hydrant to verify that water has drained from the barrel no less than 60 minutes after closing the hydrant. This establishes 60 minutes as the maximum time frame within which the hydrant must drain to be considered functional and pass the test. If water is still present in the barrel at the 60-minute check, the hydrant has failed the drainage test and requires maintenance.

A. 10 minutes is not a specified time in the standard and is generally too short for a complete drainage verification.

B. 15 minutes is a common field "rule of thumb" to see if drainage has started, but it is not the maximum permitted time per the NFPA standard.

C. 30 minutes, similar to 15 minutes, is an informal guideline for checking drainage progress, not the official maximum time for test compliance.

1. NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, 2020 Edition. Chapter 7, Section 7.3.2.5.2 states: "No less than 60 minutes following the test, the hydrant shall be checked to verify that the water has drained from the barrel."

2. Oklahoma State University, Fire Protection Publications. Fire Protection Hydraulics and Water Supply Analysis, 3rd Edition by Pat D. Brock. Chapter 10, Fire Hydrants, Section: Hydrant Testing, p. 338. The text reiterates the NFPA 25 requirement: "NFPA 25 requires that the hydrant be checked for proper drainage no less than 60 minutes after the test."