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Edwina Dorsey Valves April 14th, 2019 - 12:33:18
With the advent of the market brass ball valves, they immediately appreciated was evaluated, and the demand for these products increases, as well as their scope. Now such products can be found in any economic stall. However, despite their apparent similarity, not all ball valves are really reliable and durable. Along with high-quality Italian taps, more and more pushed over in the trade cheap Polish, Chinese and Turkish valves, whose quality is far from perfect? In the struggle for the vast US market, some sellers have begun to distribute cheap "consumer goods" for branded products, quite simply to sell a fake, so I'd like to give some practical advice to buyers' brass ball valves. As a rule, forgery in performance is much inferior to the original products. Their use in water and heating systems can lead to accidents and big material losses. Counterfeits can cause serious damage and human health.
A valve such as this operates the same as a ball valve. This valve contains a flat round plate that is placed in the middle of the pipe, as well as the plate has a bar inside that is joined to a switch in the outer valve portion. This type of valve functions by revolving the handle as well as the plate in similar position or vertical to the movement. Unlike the ball valve type, the butterfly valve is constantly present in the movement; thus there is always a moderate drop in the pressure in the movement regardless of the valve's position.
The first category is the most common one. A ball in the shell of the valve fits tightly against the side of the valve where the water comes in. Water pushing through the pipe moves the ball against the spring, allowing water through the valve. When the water is turned off, the ball is pushed into place by the spring and keeps water from flowing backward through the pipe.
Now you're probably wondering how instrument makers know how much tubing to add so that the pitch is lowered by half step. And if you're not, I'm still going to explain it! Because of acoustical theory, to lower the pitch by a half step, the working length of the instrument must increase by about 1/15, or 6.67% of the working length. For explanation purposes I will be using an instrument which is 100 inches in length (which is actually close to length of a euphonium). This means the second valve should have a length of 100/15 or 6.67" in order to lower the pitch by one half step. Now, to lower it a half step past that you must add 106.67/15 or 7.11" so the first valve must have a length of 6.67"+7.11" or 13.77 inches. Now let me explain that last statement as it may have thrown some of you off. The reason the first valve would not be simply 2(6.67) is that in order to lower the pitch by a whole step, there must be enough tubing to lower the pitch by a half step (6.67") and then enough tubing to lower that pitch a half step (7.11"). This same theory goes for the third valve, and yields a length of 21.36 inches.
Ball - the heart of the valve. Leading manufacturers attach great importance to the quality of the surface of ball valves. Brass Balls are diamond grinding, they applied anticorrosion coating of nickel or chromium. As a result, the ball gets a perfect mirror surface. Symptom of products of low quality - a dim, muddy or rough surface of the ball.
In order to achieve the best performance of valves, manufactures must take many important design factors into consideration. These factors include actuator or positioner design, valve response time, valve type and sizing, and dead band.