Check valves are a type of valve that make sure water flows only one way through a pipe. The main purpose of the check valve is to prevent backflow, which can occur when the water pressure inside a pipe is greater than the pressure in the surrounding area. Check valves have many advantages over other types of valves: 1. They are able to withstand high pressures without leaking or breaking. This means they can be used in high-pressure situations where other types of valves would fail due to excessive pressure. 2. Check valves can be used with any type of liquid or gas that flows through them. They do not require electricity in order to operate and do not require any special equipment such as pumps or compressors for operation. 3. The only moving part of a check valve is its ball valve which opens when there is an increase in pressure inside the pipe so that it can allow fluid through but closes when there is a decrease in pressure so that it does not allow any more fluid through it until it has time to adjust again and open again. Some disadvantages...
The slow-closing check valve is a special variety of check valves, which reduces water hammer pressure by slow-closing form. The slow-closing check valve has a variety of structure types, this article introduces three of them: two-stage slow-closing check valve, built-in cylinder damping slow-closing check valve, and water resistance controlled slow-closing check valve. First, two-stage slow-closing check valve This is a kind of side resistance slow-closing check valve with a double-cylinder damper, its structure principle is shown in Figure 1, the valve body is an ordinary swing check valve, but the rocker shaft of the valve flap is thicker and longer, wearing out the valve body outside, through the connection mechanism and the cylinder damper on both sides of the placement, the connection mechanism consists of the rocker arm, slide fork, and cross pin. When the pump stops, the valve flap is closed in two stages from the fully open position. Firstly, the flap falls down by its own weight, the cross pin of the rocker’s arm is lowered to the lowest point from high in the guide groove of the sliding fork, and the cylinder damper does not work, which is the fast closing stage, accounting for...
Introduction There are many different types of check valves available for a variety of applications. They all have unique features that make them ideal for specific applications. The following are the various types of valves. 1. Lift Check Valve A lift check valve belongs to a kind of automatic valve, its structure is generally composed of the valve body, valve cover, valve flap, sealing device, etc. Its main role is to prevent the backflow of media, prevent the pump and drive motor reversal, as well as release container media. Lifting check valve flap with the guide rod, the guide rod can be freely lifted in the valve cover guide hole. When the pipeline medium is in accordance with the specified direction (from left to right), the pressure below the valve flap exceeds the pressure above it, push the valve flap along the center line of the valve cover guide hole up, and the valve automatically open, so that the medium flow. If the fluid flows from right to left, that is, reverse inflow, the pressure above the valve flap is greater than the pressure below it, and the pressure difference between the upper and lower and the...
As there are more types of check valves, the design of the petrochemical plant pipelines, inevitably involves the selection of check valves. Check valve type selection is reasonable, not only affects the investment in construction and normal production of the device but also affects the safety of the pipeline system and equipment. Therefore, the choice of the check valve is very important, the main factors affecting the choice of check valve type are as follows. 1. First of all, you should understand the purpose of the process and set a check valve to meet the process requirements. When the process has special requirements for the structure of the check valve, generally should be specified in the PID (process piping instrumentation flow chart). Such as the reciprocating compressor export pipeline, the process will require the use of a non-impact check valve, the purpose is to avoid frequent fluctuations in the export pressure of the reciprocating compressor, resulting in frequent opening and impact on the valve flap, resulting in damage to the check valve. For the outlet and inlet pressure difference greater than 4.0MPa centrifugal pump, the process generally requires a different type of double check valve on the pump outlet...
Definition of Check Valve: The check valve is a device that prevents the flow of liquid or gas in one direction only. It is used in plumbing and in industrial processes. The check valve is a one-way valve, which lets water drip through it but no air can go through it from below. The check valve also provides a non-return function because it has two discs with holes on each end and when you press down on one disc, it closes off any holes above it so there’s no way for air to get into your pipes even if you have some leaks! The check valve consists of a disc or flapper valve that closes when the fluid flow reverses (i.e., when water flows up instead of down). It works by allowing for a complete seal against backflow when opened so that anything trying to come up will not be able to pass through unless there’s pressure pushing hard enough against them all at once.” Working Principle of Check Valve The working principle of the check valve is simple: When the input pressure or flow exceeds a given value, the diaphragm will be compressed,...
The globe check valve is a valve that can cut off the fluid and act as a check valve, and the connection between the stem and the valve flap is designed to be disconnected. Figure 1 shows the globe check valve to play the role of the check, in essence, is a lift check valve, its working principle, and lift check valve. When closing the valve, the stem moves downward to push the valve flap, so that the valve plays a closing role of the globe valve. When the valve is opened, the stem and valve flap are disconnected, and the valve flap can move up and down along the stem, which is equivalent to the lift check valve, when the fluid backflow, the valve flap can be closed under the action of self-weight and backflow pressure to prevent the media backflow. The globe check valve shown in Figure 1 is essentially a swing check valve, and its working principle is the same as the swing check valve. When closing the valve, the stem moves downward to push the valve flap, so that the valve plays a closing role in the shut-off valve. When the valve is opened,...
Globe valves are used in many industries. They are a popular choice for their versatility and easy maintenance. However, they have some common faults that can be easily solved to keep them running smoothly. In this article, we’ll look at the most common globe valve problems! 1. Valve body leakage Causes. 1) Poor casting during manufacturing, there are sand holes or cracks, resulting in reduced mechanical strength; 2) valve body welding when pulling crack. Elimination methods. 1) the suspected cracks at the polished, 4% nitric acid solution etching, such as cracks can be shown; 2) the crack with a grinding wheel grinding or shovel to remove the cracked metal layer for welding. 2. Stem head breakage or stem bending Causes. 1)Improper operation, excessive force to close the small valve; 2) Thread with too tight or too loose; 3) too many times the operation has been used for a long time. Elimination methods. 1) improve the operation, and avoid excessive force; Close the valve; 2)The material of the threaded sleeve should be in accordance with the requirements, and the material should be selected appropriately; 3)Replace the valve stem again. 3. Valve cover combination surface leakage Causes....
Introduction Do you want to know the difference between a globe valve and a ball valve? You should use ball valves for high-pressure applications where you need a quick response time and can’t afford any leaks. If you’re working on something that requires precise adjustments to flow rates, use globe valves. The purpose of this article is to help you understand the differences between these two types of valves so that you can choose which one is best for your needs. Structure The primary difference between these two valves lies in their construction: Globe valves have both an open side and a closed side—one chamber is always open and another always closed (except when being adjusted). Ball Valves only have an open side—there’s no closed side like there is with globe valves; rather than using two separate chambers like globe valves do though. The discs in a globe valve are flat, while the discs in a ball valve are spherical. The seats of both types of valves are made of metal, but they have different shapes. Globe valves have three-edged seats that allow movement in three directions. Ball valves have four-edged seats that allow movement in...
Introduction A globe valve is an important component for the pipes of heating and cooling systems. In order to ensure that the pipe system operates smoothly, correct installation procedures are required. 1. Check the valve body and the surrounding environment before installation Before installation, the shut-off valve should be checked, check the specifications, and identify any damage, especially to the stem. Also turn a few times to see if it is skewed because, during transportation, it is most likely to hit the stem. Also, remove the debris inside the valve. The surface of the valve body should be inspected for cracks or other defects. This is especially important if it has been in use for a long time. You should also check to make sure all the parts are there and in good condition. Check the gasket surface very carefully; if it looks like it’s going to leak, replace it before installation. For the line to which the shutoff valve is connected, be sure to clean it out. Compressed air can be used to blow away iron oxide chips, mud and sand, welding slag, and other debris. This debris, not only easy to bruises the...
Small diameter globe valve, mostly using external thread connection or ferrule connection, larger diameter globe valve can also use flange connection. Most of the globe valves are driven by a handwheel or handle, a few high-pressure larger diameter globe valves that need an automatic operation can also be driven by electricity. The flow resistance of the globe valve is large, and the closing torque is also large, which affects its application on large-diameter occasions. In order to expand the scope of application of the globe valve, at home and abroad are currently researching to improve the structure of the globe valve, in order to reduce the flow resistance and closing torque. For example, in recent years the emergence of internal pressure self-balancing globe valve. This article briefly describes the application of various types of globe valves. 1. Needle globe valve Needle globe valves are used for precise flow control. The valve flap is usually made integral with the valve stem, and it has a needle-like head that fits the valve seat with very high precision. Also, the thread pitch of the needle globe valve stem thread is smaller than that of a normal globe valve stem thread. In general,...
