THE MOST COMMON CAUSES OF DERANGEMENT.
Sand and cinders are the greatest cause of failures with injectors; as they are, indeed, with all water-feeding apparatus. I knew a case where water for a locomotive, running on a short branch, was taken out of a sandy creek with a siphon. The tank had generally about six inches of sand in the bottom. The engine had a pump and an injector; but all the feeding had to be done by the latter, for the pump never worked a gallon of water. The injector worked the water through when it seemed a quarter sand. In a short time the sand destroyed the tubes of the injector, for it acted on them the same way as a sand-blast does in cutting files or glass.
A very common cause of failure of injectors, is leakage of steam through throttle-valve or check-valve, keeping the injector so hot that no vacuum can be formed to make it prime. A great many injector-checks have been turned out too light for ordinary service, while others are made in a shape that will always leave the valve away from the seat when they stop working. Then the engineer has to run forward, and pound the check with a hammer to keep the steam from blowing back; and that soon ruins the casting. Check-valves set in a horizontal position are worthless with water that contains grit.