A SIMPLE VALVE TO PREVENT BACK SUCTION IN A VACUUM SYSTEM
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M. C. CHACO Indian Institute of Science, Bangalore, India
A SIMPLE, compact device has been worked out to prevent back suction of water from a water pump.
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ACKNOWLEDGMENT Thanks are due to Dr. B. H. Iyer and Dr. Sukh Dev
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The materials necessary for its construction are readily availableinany laboratory. It consists of a tapered glass tube of 10 cm. length and 2.2 cm. width, the wide end being closed with a one-hole rubber stopper carrying a glass tube as shown in I in the figure. A good ink filler nipple, about 4 cm. long and 1.3 cm. wide a t the wide end, preferably coated with a thin layer of silicone grease, is placed inside, the closed end pointing to the tapered end of the tube. A roll of metal wire, rolled'in the form of a spring fitted in between the nipple and rubber stopper, prevents the hole a t B from getting closed during evacuation. The end A and the opening of the tube a t A are finally closed as shown in 11. It thus prevents water from passing into the system. The valve works best in the vertical position as showu. ' This also helps to drain away any liquid present inside the tube during evacuation. The nipple will last longer if kept clean and dry. Too much contact with vapors that easily attack rubber will spoil the nipple. I11 is a modification of the valve, in which the end B is constricted.
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for their kind encouragement.
