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Edwina Dorsey Valves April 14th, 2019 - 12:31:00
So valved instruments are set up so that each valve, individually is in tune. Problems occur when performers must use valve combinations to adjust the pitch by more than three half steps. As you can see from the previous calculations, each time you add another half step, the working length must increase by more than the previous increase. Using the example of a 100" instrument, the third valve increases the length to 121.36" to produce an in-tune note three half steps below the original pitch. To lower the pitch a half step past this note, 8.09" of tubing is required. However, because the 2nd valve's length is only 6.67" this combination will be slightly sharp. This problem only compounds itself and in the 1-3 and 1-2-3 combinations, the deficit between the actual length and the "in-tune" length is 2.94" and 5.04" respectively. As you can tell, this creates a big problem, in fact, the 1-2-3 combination is about a fourth-step sharp!
A valve is a device on many instruments which redirects the airflow into a separate section of tubing before returning to the main tubing. While depressed, this "extra" tubing is in use, therefore increasing the length of working tubing and lowering the pitch. On almost all modern horns, the valves work in the same way: the 2nd valve lowers the pitch by one half step, the 1st valve lowers the pitch by one whole step (two half steps), and the 3rd valve lowers the pitch by one and a half steps (three half steps). If there is a fourth valve, it will lower the pitch by two and a half steps (5 half steps).
Brass instruments, in their simplest form are simply tubes. At one end, a musician buzzes their lips to create sound, which leaves the instrument at the opposite end. Any tube (even ones for gardening as demonstrated on YouTube) can produce wide intervals. These intervals are dictated by the harmonic series, brass players generally call this the partial series. In order to sound the notes in-between the partial series, the performer must have a way to change the length of the tubing in the instrument. Some instruments, such as the trombone have a moveable slide, while others including euphoniums, baritones, trumpets, and french horns have valves to change the amount of tubing the air flows through.
This is a valve that plays a major role in many areas of industry, including instrumentation and flow control processes. The operational environments will, on occasions, be offshore in extreme, adverse conditions such as oil and gas exploration and extraction processes. The quality and reliability of a manual pinch valve is something that can make a significant difference to an application of this nature.
One of the primarily basic and indispensable components of modern industry is the manual operated sleeve valve. In practically every manufacturing process, a control pinch valve is an essential and integral part of the production cycle. It is extremely effective in applications involving slurries or liquids and suspended solids. The valve provides a sealing process using one or more flexible elements, for example, a rubber pinch which can be pinched to shut-off a flow of material.
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