WATER RAM UTILIZED.
It is well known that water ram is constant and severe in direct pumping systems, but it is not so generally known that in a gravity system water ram is often present to a serious extent. In the gravity system now under the writer’s care the reservoir is seven miles distant; the pipe line varies from thirty inches to twelve inches in diameter until it reaches the city limits. The mains in the corporate limits are variously twelve inches, ten inches, eight inches, and six inches in diameter (no pipe smaller than six inches being in use), arranged on the “gridiron” plan. The static head varies from 275 feet in the lower portions of the city to 190 feet in the higher parts. A pressure gauge which reads 265 feet (under the static head due to its position) frequently rises suddenly to 340 feet without any apparent cause, gradually settling back to normal This is the effect of water ram caused by consumers suddenly closing their valves or fixtures when drawing water.
About two years ago we were called upon to supply water to a barn on a large stock farm located on very high ground. A careful survey revealed the fact that the water had to be delivered at a point 965 feet from our nearest mam and at an elevation eleven feet higher than the surface of the water in the reservoirs. Not caring to go to any expense for re-pumping, the writer decided to utilize the water ram existing in the pipe system to elevate the water to the barn. A branch was run from an eight-inch-main on the nearest road to the foot of the hill, where the meter was set; then a check-valve was put in, opening towards the hill; then a tee with an air-vessel on the side opening; then the pipe line went up the hill to the barn. When the water ram causes the pressure to rise above normal, the water rushes through the check-valve; when the pressure falls to normal, the check-valve closes and prevents the water from returning. The air-vessel cushions the effect of the water ram aud tends to keep the column of water in the long pipe line in motion “ between acts.” The upper floors of high buildings may be supplied with water (without expense for repumping) by placing a tank on the top floor or on the roof and using this contrivance to elevate the water to the tank. At the slock barn the water runs almost constantly during the busy hours of the day, but at other hour* it runs intermittently, whenever water ram comes on. Enough water is delivered at the barn to supply l,0i 0 head of horses.
The writer believes that, with a large number of such contrivances in use, the destructive effects of water ram will be to a great extent neutralized. The effect would be the same as applying an equal number of safety valves at various points on the pipe system (except ihat the suggested contrivances cause no loss of water, while the safety valves waste water every time they open). The only expense incurred is the cost of the check-valve end of the air-vessel, which cost is trifling on an ordinary sendee and not great on a large service.
The principle involved in this method of raising water was first discovered and applied by John Whitehurst, of Cheshire, England, in 1772. An illustration of his apparatus will be found on page 368 of “Ewbank’s Hydraulics and Mechanics.”