Nearly every pipeline system, from the most basic residential plumbing setup to the most advanced industrial variety, all implement a network of valves. Depending on the design, these valves could regulate the flow of the media, create airtight seals, prevent backflow, and more. One such valve type commonly found in many applications is the throttle valve, which is one of the most simple and underappreciated designs. In this blog, we will discuss the mechanistic action of throttle valves, where they are found, and how to choose one based on the intended operating conditions.
Like all valves, throttle valves can open and close to regulate the flow of media through a pipe, whether that be liquid, gas, or semisolid substance. However, they are unique in their ability to modulate other factors, including pressure and temperature. In order to change the pressure from the inlet side of the valve to the outlet, a pressure differential must be created by the degree to which the valve is open or closed. An easily applicable example of this phenomenon in everyday life is a gardening hose. When one turns on a water hose at a regular pressure, they may notice that the media flows out at a relatively steady yet slow rate. To increase the flow rate, one could put their thumb over the end of the hose, causing a partial obstruction wherein the water exits at a higher velocity and pressure. Additionally, when a fluid is subjected to such an obstruction, the molecules are forced to rub against each other in closer proximity, thus causing friction and an increase in temperature.
Throttle valves are not a stand-alone design, yet several commonly used valves can help throttle fluid to varying degrees. Globe valves, which are one of the most popular valves used in general, have an excellent throttling effect due to the partial obstruction created when the disk moves up and down. Unfortunately, globe valves do not hold up as well in high inlet-pressure situations and are prone to the effects of vibration. Butterfly valves are similar to globe valves and are likewise preferred for throttling applications, particularly because opening or closing the valve only requires a quarter turn. Gate valve discs are another type that move vertically in a linear fashion. The recommended usage of such valves is as a means to completely shut off or turn on the flow of media through a pipe. While not advised, they can be used to throttle fluid for a short amount of time by closing the disc to around 90% aperture. This should, however, only be done for short periods since the pressure differential will generally break the disk.
Pinch valves also fall under the definition of linear motion, yet instead of using a disk, they use two rubber sleeves that come together to block the flow of media. These, too, can be used for throttling if needed, with the highest efficiency existing around 50% of exposure. However, when using pinch valves to throttle, it is important to consider the nature of the media passing through, as the rubber sleeves are particularly prone to damage in the half-open position. Next, the bi-directional on-off diaphragm valves use a rubber-like material similar to pinch valves. However, the diaphragm design is better suited for throttling applications and less prone to wear than the aforementioned pinch valves. Finally, the globe-like needle valve is preferred in applications where a precise pressure or temperature change is needed. As such, they are best suited for accurate industrial applications and are not rated for thicker, more viscous media.
When choosing the right throttle valve, one must keep several factors in mind. First, one must consider the material of the component that will be in contact with the media and ensure that the two are compatible. For example, a metal prone to corrosion should not be placed in a pipeline containing saltwater. Next, ensure that the size of the valve is optimal for the pipe and throttling goals. Generally, the larger the valve, the less capacity for throttling. Finally, it is important to procure such valves from a reputable distributor.
At NSN World, we are a leading supplier of numerous industrial valves, including many which can be reliably used for throttling applications. As an AS9120B, ISO 9001:2015, and FAA AC 00-56B accredited company, we also understand how important it is to have high-quality components, which is why we subject much of our inventory to rigorous testing before shipping. Those measures, along with our strict NO CHINA Sourcing policy, allow our customers to buy with confidence. Explore our various parts catalogs and submit an RFQ today to join the thousands of satisfied customers who choose NSN World to be their strategic sourcing partner.
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