According to the seal structure, metal sealed butterfly valve can be divided into elastic seal structure and multi-level hard-seal structure. Production of flexible seal butterfly valve DN500 diameter generally below that of large diameter multi-level multi-use structure. Elastic structure seal butterfly by: Body, disc, stem, resilient seat, the pressure ring and other major parts. Ring structure and function of pressure: pressure side of the body ring sealing surface and the pipe flange sealing surface into sealing, bolt hole in the side, with the bolt clamping pressure from the fixed valve seat ring for use at the same time and the body as a single entity, constitutes the length of the overall structure of the valve.
As the pressure side of a screw aperture ring will effectively reduce the diameter of the sealing surface. The case of the flange from the user, mostly using a flat welding flange, the nominal Canon has been great 10-20mm. This will effectively using the sealing surface reduced, if the installation process there are different valves and pipe flanges heart, they would have misplaced pressure bolt aperture in the top, this time, exposed pipe flange bolt hole inside the hole, causing leakage here. Leakage characteristics of the medium outflow from the pressure ring on the back.
Currently, the state is not flexible metal sealed butterfly valve flange corresponding specific standard, we are under the existing national standards, provided in the flange under the same standard size, Canon used its socket type. Flange with nominal inside diameter by the same, this is to increase the effective sealing surface, but also to provide an enabling easy installation while maintaining the normal use of the valve.
At this point, to remind the user flexibility in the use of hard-seal butterfly valve, the pair must use special flange against the flange, especially paired with the valve annulus pressure pipe flanges, must use special flange.
Direction of the arrow on the body refers to the direction of the media pressure. Often cast out of the body direction of the arrow, referring to the flow of the medium, the user can see the arrow, the logical flow and direction of the arrow at the same installation, this installation has become a habit, the installation instructions were very easy to accept, by country standards for nothing wrong. But with the eccentric butterfly valve in terms of structure, so that sometimes some problems to install, said the following example: butterfly valve flow by the flow of media consistent with the installation of pipe within the medium is a liquid, the valve closed, if the original import of the direction of the media pressure, reduced or zero, the export media to anti-back flow, if the supply is high, the media, resulting in a high pressure, the pressure is greater than inlet pressure, this valve will withstand reverse pressure, Hard seal butterfly valve for ordinary use as one-way valve, such use is not conducive to butterfly valve seal, and it will leak. Concluded from the above example: valve body, the direction of the arrow refers to the direction of the media pressure. Users should be aware of before installing medium pressure valve closed direction, the free media pressure valve and the direction of the arrow to the right direction can be used, and sealing to keep in good condition.
Flexible seal butterfly valve to the user to acceptance considerations. Users of procurement in all of the valve to do sampling or testing is very necessary to do sampling on the quality of the product are: First, to ensure the quality of products, the second is to reduce unnecessary maintenance after installation and updating of the valve, a success rate of installation out. However, when a user seal butterfly sampling test, some do not pay attention to the place, causing the quality of the law can not you have suspected or unqualified rejection. The reason for the wrong? Screw on the pressure ring, respectively, according to bore size, 4, 6, 8 and 12, the bolt diameter of not more than M10. This is mainly a fixed number of screws used elastic seat, can not afford all the media pressure, when the valve is installed and then pipe flange bolts clamping effect on the outside only after all the media power to bear. Due to structural reasons, resulting in a difference operator acceptance testing leak, notify the manufacturers of the user to fail on the grounds is often the case, after the product smoothly through the communication clearance, but there is no problem in use. Therefore, in this matter should be noted that the next, for the user to better understand and use the flexible seal butterfly valve for the next exchange.
Flexible seal butterfly test, it will be upward pressure ring this side of the flat, placed in this plane and the flange of a park, the valve plate by basically the same size, if test press test, the pressure to claw pressure in the pressure plate, so that the pressure evenly distributed in the body side of the pressure ring. If the test is blind, generally flexible seal butterfly clip with two flanges are clamped on the folder to test, flange butterfly valve is sometimes flexible seal, the user only in the following order to facilitate the use of a flange bolts and the valve, then, the body above the screw on the pressure ring will bear the full brunt of the media, previously mentioned this point, these screws can not afford all the media pressure, so blind test with the valve does not leak, but also the state and the actual use of the same.
Some more frequently encountered during the installation problems, if we know the valve structure, it will give you the convenience of installation, and can correctly use the flexible seal butterfly valve.

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2011-04-19

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