Alice Campos Valves May 10th, 2019 - 13:52:00
The formula for the theoretical length of tubing, TL, needed to lower a set number of half steps, x, for an instrument of length, L, is TL = L (16/15) ^ x. Example: 100" instrument lowering 3 half steps: TL = 100(16/15)^3. TL = 21.36.
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.
Full port valves are used when there is a requirement of free flow rate of fluids. This valve has an oversized ball with a big hole to allow huge quantities to flow through it. But when there is a requirement of high pressure in the flow, reduced port valves are preferred. A common example is the pipe heads that are used for a car wash. As we require pressure in water flow, this type of valve is used in them. Trunnion ball valves have a disc or anchoring above and below the valve generally suitably when there is a large and high pressure flow rate requirement.
Many people usually get motivated to get titanium valves because they want to increase the maximum revolutions per minute that they get. An engine that has titanium valves also tend to operate better in the long run, as it receives lesser stress. Though many drivers feel that these valves are quite pricey, many also think that they are a good investment. They are apparently good for the engine, as well as the total performance of the car. However, it is just as important to check the quality of the valves being sold in the market as not all of them are of the same quality.
Why do people use titanium valves anyway? It has been found that by lessening the valve weight of an engine, there is a big impact on the reliability of an engine, as well as its performance and longevity. There have been studies that showed the performance of an engine that has steel valves compared to one that has titanium ones. Based on the sound, an engine that has titanium ones is able to accelerate a lot more smoothly. This is due to the ability of the valve springs to keep what they call the "valvetrain" under control. When the valve weight is reduced, valve springs also tend to last a lot longer, and the lifters of the engine also become more reliable. Not to mention, engines that are overhauled and fitted with valves made of titanium look a lot better than those with steel valves do. When people also use titanium valves, they will see visible results. They will be able to see that there is less wear and tear on what is called the "camshaft drive", whether it is a belt, gears, or chain.
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.