ARRANGEMENT OF SUCTION AIR CHAMBERS ON PUMPS.

What is the advantage in using a large air-chamber placed upon the suction pump? Mr. F. Meriam Wheeler, discussing this subject in a paper read before the American Society of Mechanical Engineers, calls attention to several arrangements of such chambers, good and bad. with which he has had experience, and points out how few appreciate that it is quite as important to provide them on the suction connection as it is on the discharge side of a pump, whereby water hammer is prevented, with its attendant evils.

“It must be remembered, however (he continues), that the moving column of water has considerable dynamic energy, and this should be utilized to improve the efficiency of the pump and not be a detriment to it. To avoid the noise and serious effect of water hammer, a suction air-chamber should not only be used, but it is most important that it is properly located and of sufficient size. Experience shows that water or other liquids, passing under or across the opening of an air-chamber placed at right angles to the flow, will cause the pump to pound about as much as if no air-chamber were used—except at a low rate of speed. Therefore, in arranging suction airchambers I always urge that they be so located that the energy or momentum of the column of water can be expended directly upon the confined air in them. In other words, it is very necessary to get the proper cushion effect for the column of water while the piston of the pump is reversing at each stroke, when running at anything but very slow speed.

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