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Dorothea Mccray Valves April 14th, 2019 - 12:32:13
There is a slight flaw with valves though. The valve combination of 2-3 will be slightly sharp, the 1-3 combination will always be quite sharp, and the 1-2-3 combination will always be very, very sharp. Lets explore why this phenomenon happens.
The 4th valve solves some problems and adds others. The 4th valve adds 38.08 inches of tubing in the case of our 100" instrument. This is a substitute for the 1-3 combination as the 4th valve has the correct amount of tubing to be in-tune. Likewise, the 4-2 combination produces a pitch more in-tune than 1-2-3 as it only lacks about 2.54 inches of tubing from the theoretical length. So this is great, now we have all of the seven common combinations relatively in tune right? This is true, however, this 4th valve grants access to a range which three valve instruments cannot reach. When using combinations with the 4th valve, euphoniums can reach notes such as D below the staff, a note which is not possible using three valves. Now we get to the curse of the 4th valve. When using the 4th valve in combination with other valves to reach these low notes, the problem described above compounds on itself even further. To lower the pitch a whole step after depressing the 4th valve, 19.02" must be added in addition to the length of the 4th valve. Generally, the first valve would lower the pitch by a whole step, but remember the length of the first valve tubing? 13.77 inches. Again, this problem compounds as more valves are depressed. Using the 1-2-3-4 combination, which using the half-step definitions of the valves, should provide a B natural a half step above pedal Bb. However, the length of tubing for a low B natural is a whopping 203.38 inches! The combined length of all four valves only equates to 173.22 inches... Thats only enough for a slightly sharp C! Thats right, that means that B natural is not possible (without lipping from the performer) on a non-compensating 4 valve euphonium.
As the efficiency and effectiveness of a manual sleeve valve depends on the quality and ability of the sleeve to meet the required material processing application, users must be familiar with the types of sleeves available. Whether their processing material application is related to chemical manufacturing or engineering, will determine which type of sleeve will best meet their specific needs.
Added advantages of manual pinch valves include their ability to effectively control the flow of corrosives and abrasives. In addition, there is the lack of contact between any metal part of the valve and the transported material which is a major asset in circumstances where the purity of a product is a high priority. The versatility of the valve is displayed in its ability to handle waste-water, slurries, pulp, powder and pellets, as well as applications in medical and pharmaceutical processes.
Generally speaking, the valve for low-pressure and non-corrosive fluid is made of cast iron or cast copper. The high or middle-pressure is made of cast steel or forged steel. As for the valve used in the high-temperature or high-pressure, it will select the alloyed steel as the main material. Beside, stainless steel, plastics, chlorimet such as titanium alloy or lead alloy are applicable for the main materials of the valve used for the corrosive fluid.
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.