Carly Wood Valves April 18th, 2019 - 13:23:59
A four-stroke engine is said to have a very laborious life. Manufacturers are currently downsizing the production of engines. Along with the downsizing of engines comes the boosting, which is basically means turbo-charging. However, when manufacturers try to boost engines, there is an increased pressure and temperature inside the combustion chamber. The exhaust gas temperatures also become higher. Normally, the exhaust valves already have to deal with higher temperatures compared to the inlet valve in an engine that is naturally-aspirated, and these valves could increase in temperature even further.
Needle Valves are used whenever control or metering of steam, air, gas, oil, water or other non-viscous liquids is required. This means they are used in almost every industry over a massive range of applications. Swagelok Valves are all factory tested with nitrogen at 1000 psig (69) bar to ensure that seats have a maximum allowable leak rate of 0.1 stdcm3/minute, and shell testing is performed to a requirement of no detectable leakage with a liquid leak detector.
With the increase of the steam flow rate and pressure, the plug valve can not satisfy the number of steam admission and exhaustion at all. In order to solve the problem, people then invented the slide valve. In 1840, the check valve with threaded stem and the wedge gate valve with threaded stem become the great breakthrough in the valve field. The two valves did not only meet the requirement for pressure and temperature at that time but also initially satisfy the need for flow regulation. Later, because of the rapid development of power industry, oil industry, chemical industry and shipbuilding industry, all kinds of high or middle valves sprang up like mushrooms. What's more, after the Second World War, owning to the invention of new materials such as polymeric material, stainless steel, lubricating material, the old plug valve and butterfly valve gain the new application and the ball valve and diaphragm valve develop quickly.
As a rule customarily, the sealing face for the low-pressure valve mostly applies the brass or brozen. The sealing faces of the high or middle-pressure valves are made of stainless steel. If the valve has high requirement for the temperature or pressure, cobalt base alloy is used as the main material of the sealing face. What's more, the polymeric material is widely used in the valve field. For example, PTEF material is applied into the seat of ball valves, different rubber materials for seal packing ring of the butterfly valve and septum of the diaphragm valve. All in all, the sealability of these materials is better than that of metal in the available temperature range.
Ever since the 60's, people have been using titanium to create titanium valves for various cars. Titanium is the metal of choice for the creation of spy planes that soar in high-altitudes, as well as nuclear submarines. This is also why the metal has been used for engine valves.
Needle Valves must be easy to shut off, and pressure sensitive to maintain the correct level of flow. The Valves must allow for precise adjustments of flow, and be adjustable to conform to the requirements of a particular system - Needle Valves require many turns of the valve stem to open or close, which means a range of flow, can be allowed for. They are used control flow into delicate gauges, where sudden surges of pressurized fluid can cause damaged, and in situations where flow must be gradually, and precisely brought to a halt. They are also used where a small rate of flow is required. They are not for use in simple shut off applications. The valves should be easy to shut off completely with no more than 'finger tight' pressure. Swagelok Valves guarantee a long service life, and compact design.