MIL-HDBK-1164
Determine the intervals between inspecting, testing, and overhauling each device
according to the age, condition of each device, and degree of hazard. It is important to
inspect all devices installed on Class III (high degree of hazard) cross-connections at
least once every 6 months (Table 33). In general, follow the overhaul intervals
recommended by the manufacturer. Ideally, overhaul intervals will not exceed 5 years.
Keep the inspection and testing schedule in the recurring work program.
Table 33
Suggested Intervals for Inspecting Backflow Devices
Degree of Hazard
6 Months
12 Months
Class I
x
Class II
x
Class III
x
Class III (Air Gap)
x
10.6.1
Inspection. A certified backflow inspector must inspect all cross-
connections and backflow prevention devices to ensure that:
a)
An approval air gap is maintained.
b)
Backflow prevention devices are in good condition.
c)
New devices are properly installed and debris from the installation
does not interfere with functioning of the device. (This inspection is to be completed
within 1 week after acceptance and 3 months after installation.)
10.6.2
Testing. Complete all testing according to the manufacturer's service
instructions. Repair and retest any device found to be defective until it is in satisfactory
condition.
10.7
Maintenance of Backflow Preventers. Maintenance is necessary for any
mechanical equipment to keep it operational. Therefore, it is generally best to install
any mechanical protective device in a location where it is accessible for routine
inspection, testing, and required maintenance. These devices are mechanical and
subject to breakdown, and they will need to be isolated during inspection and repair. If
there is only one service line from the potable system and if water service is required
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