a. A length-of-stroke-index must be provided for each side of pump. These must be of simple form for at all times rendering obvious the exact length of stroke which each piston is making, and thus calling attention to improper adjustments of cushion valves or stuffing boxes.
b. The gauge piece over which the index slides must have deep, conspicuous marks at ends of nominal stroke, and also light marks at extreme positions; it need contain no other graduations.
c. This stroke index must be rigidly secured to cross-head in such a way that it cannot get loose or out of adjustment.
THE WATER END.
27. Water Cylinders.
a. These must be of hard close iron with metal so distributed as to ensure sound castings, and freedom from shrink cracks.
b. The design should be along lines best calculated to resist internal pressure so as to avoid as much as possible the need of ribs for stiffening.
c. They must be capable of withstanding, without showing signs of weakness, the pressures and shocks due to running under the conditions mentioned in Chapter “Tests for Acceptance,” Art. 48-54.
The suction chamber should be able to withstand a water pressure of 100 lbs.