Exercising Valves: How? Why?
Water distribution valves of all sizes spend their lives sitting underground mostly open so that water is available to everyone on the system. If left unattended those valves will rust, suffer cathodic damage, get stuck in place, become covered in dirt and silt from the street above, get paved over, or even shift with freezing and thawing conditions if you are in a northern climate.
The act of valve exercising begins with locating the valve. Once located chances are that the valve box will need to be cleaned just to give access to the top of the valve nut.
Then, the act of operating the valve to insure that it will work if necessary completes the task.
In the act of operating the valve you sometimes find valves that were supposed to be open were somehow left closed by someone working on the system resulting in lower water pressure or flow. This is another benefit of the program.
Sounds pretty straight forward and it is. However, there are an enormous number of valves in any distribution system and the act of exercising needs to be documented to insure that all of the valves get attention that need it and that inoperable valves are documented and scheduled for replacement.
Doing this project by hand is a real chore that requires some muscle and some twisting motion that could leave your valve exerciser with a workman's compensation insurance claim for lower back pain or injury well before the project is completed.
That is why most cities and towns have employed valve operating machines to assist with the task.
Machines are equipped with revolution counters and torque read-out gauges or meters and some are connected to a computer with a GPS that confirms the location. Those computers capture data about the valve and can have other useful bits of information logged and documented as well.
Machines can operate many more valves in a day than a person can manually and they can do it day after day after day.
Complete valve maintenance units are usually mounted on either a truck or on a trailer. They might contain an excavating vacuum unit, a pressure washer, and a hydrant flushing diffuser as well as the valve operating machine.