_When one side of a duplex pump_ makes a quick stroke it indicates either that the stuffing-box gland of the opposite side is too tight or that the packing in the cylinder of the side making the quick stroke is wearing out or has, perhaps, given way. A broken discharge or suction valve will also cause a “jerky“ motion of the pistons.
Pumps should be examined frequently in order _to know what parts are beginning to wear_ and how fast the wear is taking place. When this is done the worn parts can, in the majority of cases, be taken out and replaced by new ones before they give out entirely, thus avoiding delay, but what is better, _duplicated parts kept on hand_ ready at a moment’s notice.
The regular inspection _of the screen in the separating chamber_ in the suction pipe renders frequent inspections of the interior of the pump unnecessary, the inspection previously alluded to is generally easier and more quickly done.
_Considerable wear can and frequently does take place in a pump_ in the course of six months, and for this reason it is advisable to inspect the interiors at shorter intervals, say four months for general service pumps and once in three months for boiler feed pumps. More frequent inspections should be made when handling dirty water.
_When a pump has to run faster one week than the week previous_ in order to supply approximately an equal volume of water, the plungers and valves should be examined, because such behavior indicates leakage.
_The sight feed lubricator should be filled in the morning_ so as to be empty by night, thus permitting the water to be drained out without wasting oil. Draining the delivery valve chest will also drain the delivery pipe up to the check valve if those pipes are above the chest and without water seals in them. If this pipe is arranged below the pump, then separate drain cocks should be provided and should be placed at the lowest positions in the piping.
_When a pump fails to start after standing for some time_ it should be primed by filling the barrel with water and starting the pump slowly. If after priming it fails to raise water, the suction pipe should be examined and also the plungers and the valves. If the plunger packing has become dry and hard, merely filling the water end with water will not at once remedy the trouble because the packing must be thoroughly soaked before it will work properly.