A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow. Check Valves, Water Check Valves, Brass Check Valves, Sanitary Check Valves ZHEJIANG KINGSIR VALVE CO., LTD. , https://www.kingsir-valves.com
Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.
There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with Ball Valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.
A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank Drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the backwater valve (for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.
A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
An in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.
A duckbill valve is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
A pneumatic non-return valve.
Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
How to choose a good temperature control valve products
With the reform of the heating system, household heat metering and sub-room temperature control has begun to enter the implementation stage, the installation of temperature control valve on the radiator has been very common, with the temperature control valve sub-room temperature control, both to the maximum Energy conservation, but also to meet different users to maximize the indoor temperature control needs, is a good thing to benefit the country and the people, but how to choose the temperature control valve does not completely allow users to grasp, if you can not correctly select the product, not only can not To meet the demand, and may bring unnecessary economic losses to users, this author based on their own application experience, to express their views here, designed to give colleagues and users some useful help. Thermostatic valve refers to the radiator in the water supply pipe installed on the temperature adjustment (in fact, flow control) of a device. Divided into manual temperature control valve and automatic temperature control valve two, automatic temperature control valve, also known as self-temperature thermostatic valve or automatic thermostatic valve, also referred to as thermostatic valve. Automatic temperature control valve is a temperature sensor by the self-executing agencies and a special temperature control valve body composition. Temperature control valve body structure often straight through, angle valve two kinds of the most common two-way valve. Two-way Valves are mainly used in double pipe systems or specially designed new single pipe systems. In recent years, according to the differences between single and double pipe systems, three-way temperature control valves specially designed for single pipe systems and special four-way valves fitted with dark and fitted single and double pipe systems have also been researched and produced. These four-way valves are now more common in imported products, such as giacomi-ni four-way valve Italy, it is not only suitable for a variety of radiators, but also for single and double pipe systems, but also have to meet Concealed a variety of pipe connections. Thermostatic valves are usually manual, automatic two, the valve movement principle is very different. Manual temperature control valve usually adopts the spiral lift valve core, the screw handle of the handle becomes the linear displacement of the valve core through the spiral. The automatic temperature control valve in order to adapt to the temperature sensor self-executing agencies unique linear movement, the spool movement is usually designed to automatically reset the linear displacement, so the two bodies are not interchangeable under normal circumstances. But there are interchangeable specially designed valve body can be universal, that is, the valve body with automatic temperature control valve, plus a suitable manual screw lift mechanism, you can achieve manual, automatic common interchange of the two. This improvement is particularly suitable for China's national conditions, very practical value, in many current projects, in order to save the initial investment of developers, first installed a body with automatic temperature control function and comes with a special screw lifting handle, so that both Achieved with 1/3 of the automatic temperature control valve costs (the price is basically equivalent to the manual temperature control valve) to achieve a manual temperature control valve, but also to the user in the future to achieve automatic temperature control upgrade space left. This product even in the imported products are rare, Jiekemini Italy in this regard in front of the market, providing this between the manual, automatic thermostatic valve called a double adjustment Thermostatic valve, eight settings, the room temperature set with you, extremely convenient. Worthy of the world's largest HVAC valve supplier. Precisely because of the special nature of the valve between manual and automatic thermostatic valves, the choice is more complicated and this complexity creates opportunities for some of the less fortunate and the more opportunistic salespeople. In this particular reminder is that in the current market there are many automatic temperature control valve of the supplier's sales staff will be equipped with a simple adjustment handle purely automatic temperature control valve body as a dual function of the temperature control valve to the user Recommended, and some users have adopted such a temperature control valve, which is not appropriate, there is a big hidden danger, although the automatic temperature control valve body with a simple adjustment handle, but the handle design idea Is to meet the valve in the automatic temperature control valve installed before the temporary adjustment for the system to meet the engineering test pressure test water only after the test pressure test water process is completed and replaced by automatic thermostatic valve head, Of the temporary, so the simple adjustment handle borrowed the valve body for the original fixed temperature control valve for ordinary screw thread for lifting. We all know that the simple adjustment handle because of its temporary, one-time, generally made of plastic, if the final frequent use as its adjustment, the wear of the thread is very fast, not to mention the normal heating system, the spool up and down The lifting is carried out under certain pressure. Even in the absence of pressure, the spring pressure of the valve core alone will greatly accelerate the thread wear of the handle, so the product can be upgraded to an automatic thermostatic valve Manual temperature control valve is not appropriate.