There are six major factors to consider when selecting valve sealing face materials. The sealing surface is the most critical working surface of the valve, the quality of the sealing surface directly affects the service life of the valve, and the sealing surface material is an important factor to ensure the quality of the sealing surface. Therefore, the following factors should be considered when selecting the valve sealing surface material. Corrosion Resistance. "Corrosion" is the process by which the surface of a sealingpart is damaged by medium. If the surface is damaged in this way, the sealability cannot be guaranteed; therefore, the sealing face material must be corrosion resistant. The corrosion resistance of a material depends mainly on its tensile strength and its chemical stability. Abrasion resistance. "Abrasion" is the damage caused by friction during the relative movement of the sealing surface. This damage will inevitably lead to the destruction of the sealing surface, therefore, the sealing surface material must have good anti-scuffing properties, especially the gate valve. The abrasion resistance of the material is often determined by the internal properties of the material. Erosion resistance."Erosion"refers thatthe medium flows through the sealing surface at high speed, so that the sealing surface is damaged. This damage is more obvious in the high temperature, high pressure steam medium used in the globe valve, safety valve. the sealing damage has a great impact, therefore, erosion resistance is also one of the important requirements of the sealing surface material. It should have acertain hardness, and the hardness decreases greatly under the specified working temperature. The coefficient of linear expansion of the sealing face and the body material should be similar, which is more important for the structure of the inlaid seal, in order to avoid additional stress and lose under high temperature. For use at high temperatures, there should be adequate resistance to oxidation, thermal fatigue, andthermal cycling issues. In the current situation, it is very difficult to find a sealing surface material that fully meets the above requirements. For example, for valves used in high speed media, specific attention should belaidto the requirements of erosion resistance of the sealing surface; when the medium contains solid impurities, sealing surface materials with higher hardness should be selected. Here at Dervos, we’re a leading provider for products inindustrial valve, and we’re certified with the CE, ISO, API and other institutions. We strive to offer the best quality products and customer service through our extensive experience. Contact us today for more information—we can’t wait to work with you!

Just like there are different advantages between lug or wafer type butterfly valves, 2 piece type and 3 piece type ball valves also have their edges. What below are some of the important factors when considering choices between the two types.   1. Design 2. End connections 3. Installation 4. Performance 5. Ease of maintenance   Design As their names imply, a 2-piece ball valve has two distinct pieces – one piece is an end connection and the body and a second piece, which has the other end connection as well as the valve trim.   A 3-piece ball valve has three body pieces – 2 ends and a center section that holds the valve trim. The three parts are bolted together around the three sections.   End Connections Because of their designs, two-piece ball valves are limited in the type of end connections they can make. They are usually limited to threaded end connections.   Three-piece ball valves have a swing design that allows for welded end connections, so socket and butt weld ends are often feasible.   Installation Its simple design makes 2-pc ball valve one of the most common types in many industries. Due to this simple design, the 2-pc ball valve is a lightweight solution for manual and automatic fluid or gas control.   If the end connection is threaded, the installation of the 3-pc type is also very straightforward. When it is necessary to weld the end, in order to prevent the valve seat and the sealing ring from being heat damage, the device have to be partially disassembled during the installation.   Performance The simplistic design of 2-pc valve allows itself, generally, a better Cv value. The seats, seals, applications and other parts in performance are more decisive than the design type.   Ease of Maintenance The oscillating design of the 3-piece valve allows the body section to remain in place while the valve section swings up and out of the line for cleaning or servicing. This feature makes the 3-pc stand out from the 2-pc, whose design does not allow for any maintenance. Applications where the media is thick or viscous, or where lines must be cleaned between batches, are almost always the domain of the 3-pc valve.   summary Based on the above information, the consideration of 2-pc or 3-pc must include various factors, including the length of the production line through its medium, flow, weight, and maintenance plan. The good news is that our technical sales staff will be more than happy to discuss these factors so that you can make the right decision.   Xiamen Dervos has served countless industrial, commercial, and municipal clients for over 10 years. We have supplied thousands of common valves, customized products, electric and pneumatic actuators and so on to customers worldwide.   If you would like to know more about our valves, services, or other products, any message or inquiries are welcomed.

Generally speaking, a plug valve and a ball valve may absolve the same function (fluid shut-off). The main differences are:   Plug valves are more economical than ball valves, generally, due to their simpler design   Plug valves are less prone to contamination by debris, and accumulation of dirt in the interstitial spaces, compared to ball valves (an issue that is frequently faced by ball valves, due to the spaces existing between the sphere and the body of the valve)   Ball valves require more maintenance than plug valves, especially after planned or unplanned plant shut-downs   Plug valves have a full port design, without pressure drops, ball valves may be reduced or full port (a full port ball valve would be heavier and bulkier than a plug valve of the same size)   In general, plug valves are good alternatives to ball valves, even if ball valves are still considered industry standard for shut-off operations at least in the oil & gas industry.

The V-ball valves or V-port ball valves are similar to traditional ball in which there is a V-notch on a ball-shaped disc to control flow by a rotating quarter-turn motion. The “V-port" is a particular design that bring about precise flow and the ability to regulate and control flow by V balls of  different degrees. These special valves are used in a wide range of chemical applications, including the most challenging services with many advantages.   Flow Modulating The accuracy of V-ball valves provides equal percentage flow characteristics. As the ball rotates, desired flow rates can be achieved by positioning the ball anywhere between 0° and 90°.   Bubble tight shutoff V-ball valves have the ability to close tightly. Therefore, no other shutoff valves is required when using a V-ball valve on a globe valve.   Lower pressure drop V-ball valves also have a higher coefficient of flow (Cv) than the same size globe valve, which directs the flow and uses a plug to control the flow through the valve. This means that the flow rate achieved by one shut-off valve can be achieved with a smaller V-ball size.   Higher shutoff pressure. A 90°rotation of the ball allows the V-ball to close at a higher operating pressure. This therefore allows the use of lower torque actuators, resulting in cost savings and increased efficiency for the end user.

There are quite a few types of changeover valves, and according to different standards, there are different subdivisions. But in general, it is mainly four kinds, for motorized changeover valve, manual changeover valve, solenoid valve and electro-hydraulic changeover valve.   1. What is a changeover valve?   Changeover valve, from a professional point of view, is a kind of direction-change valve. It is mainly used to achieve the flow of hydraulic oil, cut off the machine changeover operations, pressure relieving, as well as sequential action control, so its use is very wide.   2. The working principle of reversing valve   The changeover valve uses a  driving mechanism outside the valve to rotate the drive shaft, and then activates the valve plate, etc. So that the fluid can flow into the outlet of the lower part of the valve, and can be changed from time to time to achieve the purpose of periodically changing the flow direction.   3. Changeover valve classification  (1) Motorized changeover valve, it is also known as a stroke valve.    (2) Electromagnetic changeover valve, electromagnetic changeover valve is the use of electromagnetic attraction to manipulate the spool changeover control valve.    (3) Electro-hydraulic changeover valve, electro-hydraulic changeover valve is a composite valve composed of solenoid valve and hydraulic changeover valve.    (4) Manual changeover valve, manual changeover valve is a changeover control valve with a manual lever to manipulate the spool shift direction-changing valve.  

Among the anti-corrosion materials, PTFE has incomparable excellent performance. In addition to outstanding chemical stability, it also has satisfactory anti-fouling and anti-stickiness, small dynamic and static friction coefficient, good anti-wear performance. Using it as a valve opening and closing the sealing material, the friction between the sealing surface and required operating torque will be reduced, hence product life increases. the application scope can also be extended to the food, pharmaceutical industry and so on. Fluorine lined valves, also known as anti-corrosion valves, are usually found in harsh working conditions. The media is either toxic and harmful chemicals, or pretty corrosive acids and bases or organic solvents. That means improper use and operation will elicit significant economic losses and serious consequences. Applicable media: various concentrations of acid and alkali salt and certain organic solvents. Fluorine is extolled as the world's most ideal anti-corrosion materials, has been widely used in the rotational molding of large equipment and piping lining. Correct use and maintenance of the valve can extend the service life of fluorine lined valves, then what can be done to effectively protect it? 1. Carefully read the instruction manual before use. 2. Use it within the range of pressure, temperature and media given by the nameplate or instruction. 3. To prevent fluorine lined valves from excessive piping stresses due to temperature changes, temperature changes should be minimized and U-shaped expansion joints should be added before and after the valve. 4. For some unstable and easily decomposed media (such media will expand after decomposition,  resulting in an abnormal pressure rise) and media that can cause valve damage or leakage, measures should be taken to eliminate or limit the factors that cause the decomposition of unstable media. 5. For fluorine lined valves in pipelines of toxic, flammable, explosive, highly corrosive media, it is strictly prohibited to replace the packing under pressure. Even the valves are designed with sealing part, it is not recommended to replace the packing under pressure either. 6. For pipelines with self-combustible media, measures should be taken to ensure that the ambient and working temperatures do not exceed the self-combustibility point of the media to avoid the danger from sunlight or external fires.