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ball valves, noisy
Значение термина ball valves, noisy в knolik
ball valves, noisy - ball valves, noisy
ball valves, noisy - Doubtless every practical man has experienced more or less trouble from this cause, and in some cases quite frequently. It is not at all a rare complaint, but it is one generally of a very annoying nature to all who may be residing in the house where the valve is.
There are two kinds of sounds, due to two quite different causes. One is a deep humming; the other a jarring or jumping noise like successive shocks more or less quickly repeated. Both are only noticeable when the valves are partially or nearly closed. A full-open valve seldom makes a noise of a disagreeable character. If it does it had best be changed for another.
The humming noise is heard with valves on a high pressure service as a rule. As the valve closes and the passage through it becomes more restricted, the strain exerted by the water and consequent friction causes the noise to occur. We may well liken the effect, if not the cause, to what takes place in a steam-horn or whistle. The steam is arranged to pass into and through a restricted but suitably shaped outlet aperture, and a very distinct noise is the result, if the pressure is sufficient. The volume of steam and the pressure have to be in some exact ratio with the area of the outlet aperture, and this is so with the ball-valve when it is closed sufficiently. If the ball-valve aperture could be kept fully open until the moment of closing, no noise of the kind could occur, as the proportions of the outlet, with the volume and pressure of the water, would be wrong, the former being of too great an area to the latter for the production of sound vibrations.
The measures that can be adopted to prevent this humming noise are, therefore, two. One is to put a larger ball-valve, or a valve with a more roomy way through it. The other is to reduce the pressure and the volume of water coining to the valve. The latter is best and oftentimes the easiest. The method of doing it is to choke the service close behind the valve, practically reducing the bore of the service-pipe; This might be effected by pinching the pipe, if it is lead, or by taking the valve off and putting a piece of small tube or a nipple-piece in the boss or tube which the valve is screwed into. Another way is to solder a piece of sheet metal over the tail aperture of the valve - the tail being the part that screws into the boss or pipe - then boring a 1/8 in. or 3/16 in. hole in it. Still another way is to insert a stop-cock just behind the valve. This could be closed to any desired extent to check the volume and the pressure of water. The results will be identical with checking the service tube to a steam-whistle: plenty of steam may come through, but the sound will be wanting. Checking the service pipe to the ball-valve cannot do any harm or cause any inconvenience. There will still be abundance of water come through for all ordinary purposes.
The other noise that occurs with ball-valves, and which is more or less a chattering kind of disturbance, is caused by the movement of the water in the cistern. As water enters the cistern, falling into it with some force, that which is already there becomes agitated, and assumes the character of little irregular waves on the top. When the cistern is sufficiently full to begin lifting the ball of the ball-valve to close it, the ball is not lifted in a slow and regular manner, but is caused to move up and down on the disturbed water. When the valve is about half, or a little more than half closed, the ball when lifted by the disturbed water wholly closes the valve, but only to open again and then close as fast as the agitated water moves it. If the water coming in is served at a fair pressure there will be a distinct noise and shock every time the valve is thus opened and then abruptly closed. This is a noise, which makes itself heard throughout the house, and in point of their irritating qualities there is little to choose between the two. Where there is an intermittent water supply the trouble only occurs once a day, but with a constant supply it may occur every time the tap is opened. The remedy for this latter cause of noise and annoyance is to prevent the agitation of the water in the cistern by that flowing in. This is simply effected by fixing a tube to the nose or outlet of the ball-valve so that the water it discharges does not fall on to the water already delivered, but delivers it below the water level. A piece of rubber tube fixed to the nose of the valve and allowed to drop about half-way down the cistern will do; or a piece of metal tube can be soldered on. If the inflowing water enters beneath the level of the water already there, it will not agitate it, or cause the valve-ball to dance up and down. ('English Mechanic.')
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