In
one case, as part of an overall building improvement program, all of the gas
lines in the building were re-painted yellow, the colour indicating a natural
gas line. It looked great. However, when we went to exercise the emergency gas
shut-off valves, we discovered that the valve had been painted as well, and the
valve was well and truly stuck in the open position. Fortunately this was
discovered during a routine inspection and corrected. Imagine if this had been
the case during an emergency!
In
another case, we operated some needle valves on the Domestic Cold Water Booster
Pumps in order to do some testing. These valves had not been exercised in years.
The result was a failure of the Low Suction Pressure Limit on the system and
resulted in a loss of water in the building for a number of hours.
There have been countless cases over the years where work has been delayed or re-scheduled because isolation valves that were supposed to allow work to be done on the plumbing systems did not “hold” (work as designed and “hold” back the water).
Exercising valves is a good maintenance practice and should be done on a regular basis. It only takes a few minutes to exercise a valve, but it can mean hours or days on a job when it is suddenly discovered that these valves don’t work.
The same “exercising” principal can be applied to lead / lag equipment. For example, a pump system may be set up where if the lead pump fails, the lag (or back-up) pump will kick on. If the lag pump is not exercised periodically, the seals on the pump can deteriorate, ‘dead-spots’ in motor windings can develop, and couplings can fail when first started.
A good building exercise program begins with a list of priority valves in the building. These include, main water shut off, gas valves, riser isolation valves, and builds from there. A little exercise can go a long way.
