The relief valve adjusting safety technical operation procedures
1) open pressure adjustment
(1) the relief valve before they leave the factory, by Taiwan should adjust its open pressure to the user's setting value. If the user work pressure level proposed spring, the general should press pressure level adjustment the lower limit of the factory.
(2) users will install to be in the relief valve protection equipment before or before installing, must be adjusted to install the spot, in order to ensure that the valve setting pressure value meets the requirement.
(3) in the spring working pressure nameplate indicating level range, through the rotating adjustment screw change spring compression, can open pressure to adjust.
(4) in the rotation adjustment screw before, should make the valve inlet pressure to reduce pressure to open the below 90%, in order to prevent the adjustment screw rotation when the disc is driven rotation, so that the sealing surface damage.
(5) to ensure accurate open pressure value, should make the adjustment of media condition, such as media types, temperature, the actual operating conditions as close as possible. Medium type change, especially when the media is not the same as the buildup of state (for example from liquid into a gas phase), open pressure often is changing. Working temperature rises, open pressure generally reduced. So at normal temperature adjustment and used for the high temperature, under normal temperature setting pressure value should be slightly higher than the required open pressure value. High to what degree and valve structure and material selection have relationship, should with factory instructions for according to.
6 for a conventional relief valve additional back pressure situation, when in the inspection after open pressure adjustment (this time back pressure for atmospheric pressure), its setting value shall be the requirements of the open pressure value minus the additional back pressure value.
(2) emission pressure and back to a pressure adjustment
(1) adjust discharge valve pressure and back to a pressure, must be valve up to the height of the open action test, therefore, only in the large capacity test device or in the relief valve installation to be protective equipment after on possible. The valve structure adjustment method in different and different.
(2) with the plate and the seat to recoil circle structure adjustment, is using the seat ring to adjust to adjust. Back off adjusting screw circle, from the stretch out screw holes people a thin rods of iron and tools, can adjust the circle turn the gear, make the adjustment circle turn right or left. When make adjustment to the left circle for counter-clockwise, its position increases, pressure and back to a discharge pressure will be reduced. Conversely, when make adjustment to the right for circle clockwise, its location is reduced, pressure and back to a discharge pressure to rise. Every time, when adjustment to adjust: circle the range of the rotation shoulds not be too large (general turn several teeth can). Every time after adjustment should be fixed on the set screws, make the aft adjust circle in two teeth slots in between, and can not only prevent adjust rotation circle, and no adjustment radial stress produced circle. For safety's sake, pick adjustment in circle before, should make the relief valve inlet pressure appropriately reduced (general should be less than 90% of the open pressure), to prevent the adjustment valves open when suddenly, cause an accident.
(3) has, under regulation for the circle (orientation set and seat each have a regulation circle) of the structure, and its adjustment is more complicated. Adjust seat ring to change the disc and adjust the size of the channel between circle, which changes the initial pressure when open valve in the disc and adjust indoor accumulation degree between circle cavity size. When rise seat adjust lap, pressure increases the accumulation of degree, so that the proportion of the valve opens and faster to reduce stage of rapid suddenly open. Therefore, adjust seat ring elevated can make emissions reduced pressure. Should pay attention, adjust seat ring nor rise too close to the disc. So, the leak sealing surface place can lead to premature valve suddenly open, but because at this time to media pressure will keep the disc in the open position, disc immediately and close, so the valve occurred frequency jump. Seat adjustment: "the circle is mainly used to narrow the valve and open the proportion of the stage and regulating emissions, but also to pressure back to a pressure have an effect.
Adjust on the circle used to change the flow media in the disc to the underside of the reflected turning Angle and change the size of the fluid forces, in order to adjust to a pressure. The increased regulation lap, fold the corner decreases, and fluid force then decrease, and make back a pressure. Conversely, when reduce adjust on the lap, back to a reduced pressure. Of course, adjust on the circle in the change back to a pressure at the same time, also influence to discharge pressure is increased pressure to adjust on the circle has increased emissions, reduce emissions to adjust on the circle pressure decrease, but its influence degree is inferior to back to a pressure that obvious.
(3) seal
The relief valve adjust finished, should try to seal to prevent literally change has adjusted good condition. When the valve repair, in remove valve should take down before adjusting screw and adjust the position of the circle, in order to recast adjustment. To adjust to seal shall be again.
|
