Butterfly valve - operating features. Wafer valves Application of butterfly valves
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A butterfly valve is a type of shut-off valve installed on pipelines to shut off the supply of the working medium to a specific section of the pipeline. The use of valves is widespread in water supply, sewerage and municipal heating systems. In pressure pipelines, where the working medium circulates under high pressure, such fittings, due to the inability to ensure complete shutoff tightness, are not used.
This article presents flanged butterfly valves. We will consider their design features and operating principle, advantages and disadvantages, installation technology.
Contents of the article
Operating principle, design features
A characteristic feature of butterfly valves is that the shut-off element has the shape of a disk, which is located perpendicular to the movement of the working medium transported through the pipeline. When the flow is cut off, the disk rotates around its axis by 90 0 and blocks the passage opening of the valve.
A flanged valve can also be called a damper or a sealed valve. Depending on the method of rotation of the locking element, valves are classified into two types:
- axial (the shutter rotates around its central axis);
- eccentric (rotation occurs around the eccentric axis).
Both types of fittings have identical scope of application. As a rule, they are equipped with large-diameter pipelines with a minimum operating pressure of the transported medium, the operating rules of which do not impose strict requirements for the tightness of the fittings.
Butterfly valves are used in the following areas:
- water supply and heating;
- air conditioning and ;
- gas supply and pipelines for supplying vaporous substances;
- petroleum products, non-aggressive chemical liquids;
The design of this type of fittings provides for the possibility of manufacturing a locking disc of sufficiently large thickness, which gives it increased wear resistance. Special modifications of valves designed for abrasive granular media, in which other types of pipeline fittings have a limited service life, are widely available on the market.
Requirements for the design and technical characteristics of valves are given in the regulatory document GOST No. 12521-89 “Wafer disc valves. Main parameters", according to which the fittings have a standard layout consisting of the following components:
- Steel or .
- Drive of manual or mechanized type (electric, hydraulic, pneumatic).
- Disc-shaped locking mechanism.
- The rod connecting the disk to the drive.
- A sliding unit, inside which a rod rotates, consisting of a locking and thrust ring, a cuff, and an o-ring seal.
- Fasteners that secure the valve to the rod.
- A round hole through which the disk rotates inside.
- The lower part of the rod that extends from the disc and acts as an additional retainer.
- A stop screw that prevents the rod from moving during rotation.
The principle of operation of the valve is extremely simple - the drive transmits the torque to the locking disc, which changes its position by 90 around its axis and closes the passage hole. The sealing of the housing in relation to the environment is achieved through the use of sealing collars and gaskets made of fluoroplastic or synthetic rubber.
Note that the butterfly valve can only be used as a locking valve, that is, its locking disc must be placed in the extreme positions - “open” or “closed”. If it is necessary to use control valves, analogues are used -.
Advantages and disadvantages
The wide distribution of this type of fittings in various fields of industry is due to the presence of many operational advantages, the main of which are:
- minimum overall dimensions and weight;
- extreme simplicity of design and a relatively small number of components;
- maintainability of fittings, possibility of replacing sealing surfaces;
- resistance of the locking mechanism to the mechanical effects of abrasive substances;
- ease of installation due to the flange connection (there are also wafer valves, which do not have their own connecting plates but are clamped between two adjacent pipeline flanges).
The disadvantages of the design include the inability of the standard fittings to ensure complete tightness of cutting off the working medium. Only valves with a soft seat seal are classified according to tightness class “A” (complete absence of leaks). The fittings, the sealing surfaces of which are made in the “metal to metal” configuration, belong to class “B”.
Another operational disadvantage is the complexity of controlling valves of large diameters due to strong torques - all valves with a diameter of over 150 mm are equipped with gearboxes that facilitate the effort required for control. We also note that in the open position of the valve, the shut-off disk is located inside the through hole of the housing, which leads to a loss of pressure in the working medium and complicates mechanical cleaning of the pipeline.
Standard sizes and markings
The fittings have standard type markings 32s3p du50ru10, wherein:
- 32 – type of fittings;
- c – steel body;
- 3 – the drive is equipped with a mechanical gearbox with a worm gear;
- p – material of sealing surfaces: plastic;
- DN50 – connecting diameter 50 mm;
- ru10 – nominal operating pressure 10 kgf/cm 2.
Wafer structures, in accordance with the provisions of GOST No. 12521, are produced in diameters of 100-1600 mm. The fittings are divided into 4 classes depending on the operating pressure: up to 0.1 MPa, up to 0.25, up to 1 and up to 1.6 MPa. The products are intended for operation at operating temperatures from -60 to +300 degrees.
A separate category includes valves with titanium alloy bodies, the diameter range of which varies between 100 and 1000 mm. They are designed for pressures up to 0.63 MPa and a maximum temperature of +300 0.
Operating a flanged valve (video)
Features of check valves and installation technology
There is a subtype of this type of fitting called a check valve; another common name is a flap. The functional purpose of this design is to limit the possibility of reverse movement of the working medium transported through the pipeline.
The check valve has a different design. In it, the locking mechanism is fixed not on the rod connecting it to the drive, but on an axial spring, which fixes the disk on the through hole of the housing. When operating in standard operating mode, the disk moves under the pressure of the circulating medium and opens the through hole, which allows the flow to move in a given direction.
If the direction of movement of the working fluid changes due to decreased hydraulic pressure, the locking disk, under the influence of the spring force, returns to its original position and closes the through hole, preventing the reverse flow.
Depending on the design, the check valve can be:
- simple;
- unstressed.
Simple designs are available in diameters up to 400 mm inclusive. Impact-free fittings differ from them in the presence of additional dampers that ensure a soft landing of the disk when slamming. However, shockless latches are limited in their use - they can install exclusively on horizontal sections of the pipeline.
Most butterfly valves have a steel wafer body, on the connecting plate of which the same arrangement of mounting holes for fasteners is provided as on the pipeline flanges. Wafer structures are characterized by a minimum construction width - they are installed between two flanges of adjacent pipes, which are tightened with screws and nuts and clamp the fittings together. The tightness of the connection is achieved through the use of sealing gaskets made of paronite or rubber.
The Aglant company offers to purchase from a warehouse in Moscow the most profitable and reliable solution in terms of price-quality ratio on the pipeline fittings market - a wafer butterfly valve, a product designed to shut off and regulate work flows and media on industrial pipelines and process lines.
Features, technical data and benefits.
The main difference between this type of fittings is its installation method - the wafer connection is carried out by tightening the collar flanges of the pipe with holes in the smooth eyes of the valve using bolts or studs, which, first of all, is one of the advantages and a consequence of reducing weight and construction dimensions. Wafer type butterfly valve in the general range of models represented by all sorts of world brands and companies is represented by a wide number of different solutions that can be combined by basic characteristics, such as: the nominal diameter of its passage channel, DN from 20 mm to 1200 mm, and the pressure with which The following devices work - PN 10 and 16 bar. Basically, the material used for the body parts of wafer butterfly valves are high-strength grades of cast iron and carbon steel alloys. The locking element is made in the form of a disk rotating inside the passage channel and a seal around it made of silicone, perbunan, polyurethane, Viton or EPDM. The permissible climatic and operating conditions for using the device directly depend on its material, which cover temperature conditions from -20...+210°C, which in turn are associated with the internal pressure of the medium in the pipeline. The manufacturer guarantees a fairly long service life, indicated at 10 thousand operating cycles of closing/opening when working with dry media, gas, and approximately 100 thousand of the same cycles in liquid media. The tightness of the valve corresponds to class A in both directions, installation in any position on the work surface is allowed, as well as one-sided locking using a blind flange - 3 bar for DN 20 - 250 mm and 2 bar for larger sizes DN 300 - 600 mm.
Application.
The scope of application of wafer butterfly valves today are:
Food and housing industry
Wastewater, drainage, heating and sewerage
Chemical, petroleum and shipbuilding systems, etc.
How to purchase wafer-type shut-off valves from us?
Our managers are always aware of all the new products and trends in the industrial construction market, and the inventory in the warehouse is kept up to date. Our website may not list all available products, so if you have not found the item you are interested in, please contact us in a convenient way - by email, phone or by filling out the feedback form on the website to receive help and advice in choosing the required product or its analogues. In addition to free delivery throughout Moscow and the region, we periodically deliver to the terminals of transport companies in other cities of the Russian Federation: Ekaterinburg, Ufa, Nizhny Novgorod, Samara, Krasnodar, Rostov-on-Don, Chelyabinsk, Kazan and the Far East.
Wafer valve is a type of pipeline fittings used to regulate and completely shut off the pressure in heating and water supply systems (drinking and general industrial water). The NEMEN company offers to purchase wafer valves from leading European manufacturers.
Wafer type valve design
The main working element of the entire mechanism is a disk located parallel to the axis of the pipeline, which rotates 90 degrees to close or open the flow. The main material of the valve body is cast iron, steel or stainless steel, the locking product is stainless steel or nickel-plated cast iron. The fittings are additionally equipped with saddle seals made from EPDM, NBR, VITON, etc.
Butterfly valves with a diameter of 50-300 mm are equipped with a rectangular stem with rounded chamfers, designed to close or open the disc. Models with sizes 350-600 mm use round rods. If desired, the valve can be equipped with a gearbox or electric drive.
Shutter installation features
- Installation of wafer fittings is carried out using collar flanges, the size of which corresponds to the inlet/outlet diameter of the mechanism.
- The valve must be installed without gaskets.
- First you need to weld the flanges to the pipeline and only after they have completely cooled, install the main mechanism.
- During installation, the device must be opened slightly so that the locking disk does not protrude beyond the edges of the housing.
- The bolt studs must be tightened crosswise until the gap between the valve body and the flange is completely eliminated.
You can purchase a wafer valve and consult with NEMEN specialists by contacting them at the numbers listed in the “Contacts” section.
A wafer rotary valve with a gearbox is a simple type of shut-off valve made of durable steel, manufactured by casting or stamping. It is in demand for shutting off the liquid working medium in pipeline networks and technical lines. It only works in two positions: “open” or “closed”. A wafer device, unlike a flanged valve, cannot be used with media of extremely high temperature and high pressure, and is often used in cold water supply networks.Select the required product options