Casting method are widely used in valve industry. In this article, we will discuss the merits and demerits of cast steel valve.   Merit 1. Cast steel valves are made from liquid metal, thus it is more flexible in size and shape, even in complex shape. 2. There is a great variety in terms of material and its chemical composition. Thus, alloy steel valves are often made of casting method. 3. The less complicated and expensive process leads to its wide availability. 4. Cast steel valves have a contoured shape with round edges. This makes them easy to install even in small spaces and pipelines.   Demerit 1. Some material is lost when melting. The liquid is then reworked as it is put into and removed from molds. The overall process will generate lots of material waste. 2. There can be some impurities like cracks and voids during its solidifying process. This will lead to a lower mechanical property. 3. The heat treatments can alter the micro-structure of the castings after welding. This results in higher creep and lower hardness of the valve. Rigorous inspection is required to make sure the valve has retained its strength and creep resistance after being welded.

The plug valve is a relatively old type of valve, including sleeved plug valve,lubricated plug valve and multi way plug valve. It relies on the plug body to rotate around the center line of the valve body to achieve the purpose of opening and closing. The function of the plug valve is generally used to cut off, distribute and change the medium flow direction. The plug valve has a simple structure; the external dimensions are small; only 90% of the fluid resistance is required during operation. It is widely used, especially in low pressure, small diameter and medium temperature. The disadvantages of the plug valve are that the switch is laborious, the sealing surface is easy to wear, and it is easy to get stuck at high temperature and pressure, which is not suitable for regulating the flow. The ball valve is evolved from a plug valve. Its opening and closing member is a ball. The ball is rotated 90 degrees around the axis of the valve stem to achieve the purpose of opening and closing. It is mainly used to cut, distribute and change the flow of the medium Orientation, the ball valve designed as a V-shaped opening also has a good flow adjustment function. When used for shut-off, the plug valve has a slightly better adjustment capacity than the ball valve, but has limited advantages. Although the plug valve has a sealing surface much larger than the ball valve, the sealing effect is good, but it also brings the disadvantage of too much torque and insufficient flexibility. Due to the influence of the weight of the cock, the conventional positive cock structure is difficult to achieve a large caliber. If you want to use a large-size valve, you must use an inverted cock structure, that is, the cock has its head pointing down. This inevitably reduces the sealing effect under the action of gravity. It has to be sealed by grease injection. It is used for storage and transportation of natural gas and oil, but cannot be used in other industries, because grease will contaminate the medium. Although the ball valve's sealing effect is slightly poor in theory, it can be made into a large caliber. With the improvement of processing accuracy and sealing material, the ball valve's sealing effect can already meet the actual application requirements, and the application range is wider. When used for adjustment, there is not much difference between the two, and appropriate holes can be made in the rotating body for adjustment. Therefore, the general plug valve is used in occasions with higher sealing requirements, but the diameter is generally smaller, and the ball valve can be applied to more and more extensive industrial occasions.

Ball valve is a kind of valve that uses a ball with a circular channel as the opening and closing parts, and the ball rotates with the valve stem to realize the opening and closing action. We supply various trunnion mounted ball valve,floating ball valve,fully welded ball valve and other multi way ball valve. Ball valve is evolved from plug valve. They have the same 90 degree rotation action, the difference is that ball valve has a ball with circle port, while plug valve has a plug in the shape of cylindrical or conical. In a cylindrical plug, the channel is generally rectangular; in a conical plug, the channel is trapezoidal. The main feature of ball valve is its compact structure, easy to operate and maintain and suitable for not only general working media such as water, solvents, acids and natural gas, but also for media with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene. Besides, ball valve body can be integrated or combined. Generally speaking, ball valves are most suitable for directly opening and closing, but recently, ball valves have been developed and designed to throttle and control flow. Ball valves are one of the most supplied valves at dvsvalve.com.

Dervos here announce that we officially go back to work on Feb 3rd, 2020. Currently, we are working at home due to influence of Coronavirus outbreak. We will return to our office on Feb 10th,2020. We also launch a donation activity for against Coronavirus. Please refer to the link below for further information. Dervos Donation Plan

In the past two weeks, the whole country have been uniting together to fight against Coronavirus outbreak in China. We learn that due to a severe shortage of medical supply in domestic, many medical staff will work for more than 4 consecutive hours without drinking water or going to washroom to save masks and protective clothing as much as they can. Dervos people want to do something for our country. We have a donation plan to offer medical supply to frontline. If you have related resources, we here invite you to join us and help us purchase medical supply like masks abroad. We will pay for the cost. Below is a letter of our formal request. If you are interested in our donation plan, just send us email at virus-shooter@dervosvalve.com. We appreciate all your kindness and care in advance!!!

Double eccentric butterfly valve is further improved on the basis of single eccentric butterfly valve. Its structural feature is that the axis of the valve stem deviates from both the center of the disc and the center of the body. The effect of double eccentricity enables the butterfly plate to detach from the valve seat immediately after the valve is opened, which greatly eliminates unnecessary excessive squeezing and scraping of the disc and seat, reduces the opening resistance, extends valve seat life. The double eccentric butterfly valve also adopts metal seat, which improves the application in high temperature field. Double eccentric butterfly valve is also called high performance butterfly valve. It is mainly used for drainage of water plants, power plants, steel plants, chemical engineering, water source engineering, environmental facilities and other systems. Structural features of high performance double eccentric butterfly valve: 1. Reasonable design, compact structure, easy assembly and disassembly, and easy maintenance. 2.Eccentric structure is adopted to reduce the friction of the seal ring and prolong the service life of the valve. 3, Completely sealed, zero leakage. Can be used in ultra-high vacuum conditions. 4. Replace the seal ring, disc, shaft to different materials, which can be used for a variety of media and different temperatures.