German PRAHER valves PRAHER models PRAHER prices

The closing element of the PRAHER valve is a plug-shaped disc, with a flat or conical sealing surface. The disc moves linearly along the centerline of the valve seat. The stem movement type (commonly known as non-rising stem) also includes rising-rotating stem types. It can be used to control the flow of various fluids such as air, water, steam, various corrosive media, slurry, oil products, liquid metals, and radioactive media. Therefore, this type of stop valve is very suitable for shut-off, regulation, and throttling. Due to the relatively short opening or closing stroke of the valve stem of this type of valve, and having a very reliable shut-off function, and because the change in the valve seat passage is directly proportional to the disc stroke, it is very suitable for flow regulation.

PRAHER valve globe valve features

Compared with another commonly used shut-off valve in industrial production, the gate valve, the globe valve has a simpler structure, making it easier to manufacture and maintain. In terms of service life, the sealing surface of the globe valve is not easily worn or scratched. During the opening and closing process, there is no relative sliding between the disc and the seat sealing surface, resulting in less wear and damage to the sealing surface, thus improving the service life of the sealing pair. The globe valve has a small disc stroke during the fully open and fully closed process, and its height is relatively smaller than that of the gate valve. The disadvantages of the globe valve are that the opening and closing torque is large and it is difficult to achieve rapid opening and closing. Because the flow channel inside the valve body is quite tortuous, the fluid flow resistance is high, causing significant loss of fluid power in the pipeline.

Precautions for PRAHER valve performance testing

1) When valves of a certain specification are manufactured in batches, an official agency should be commissioned to perform the following performance tests: (1) Opening and closing torque of the valve under working pressure conditions; (2) Detection of the flow resistance coefficient of the valve under pipeline water transmission conditions. 2) The following tests should be performed on the valve before leaving the factory: (1) With the valve in the open position, the valve body shall withstand an internal pressure test at twice the valve's working pressure value; (2) With the valve in the closed position, both sides shall separately withstand 11 times the valve's working pressure value without leakage; however, for butterfly valves with metal seals, the leakage value shall not exceed the relevant requirements.

PRAHER valve operation

For globe valves, one must not only know how to install and maintain them, but also how to operate them. When opening or closing a globe valve, apply force steadily; do not use impact. For certain high-pressure globe valves designed for impact opening and closing, the components have already accounted for this impact force, which is not equivalent to that of general globe valves. When the globe valve is fully open, turn the handwheel slightly in the reverse direction to tighten the threads and prevent loosening and damage. When the pipeline is first used, there may be a lot of dirt inside. You can slightly open the globe valve and use the high-speed flow of the medium to flush it away, then close it gently (do not close quickly or forcefully to prevent residual impurities from damaging the sealing surface), then open it again. Repeat this process several times to flush out the dirt before putting it into normal operation. For normally open globe valves, dirt may adhere to the sealing surface. When closing, use the above method to flush it clean, then formally close it tightly. If the handwheel or handle is damaged or lost, replace it immediately. Do not use an adjustable wrench as a substitute to avoid damaging the square part of the valve stem, which could lead to ineffective opening/closing and cause accidents in production. For some media, cooling after the globe valve is closed causes the valve parts to contract. The operator should close it again at an appropriate time to ensure no fine gaps remain on the sealing surface. Otherwise, the medium flowing through the fine gaps at high speed can easily erode the sealing surface. During operation, if the operation feels excessively difficult, analyze the cause. If the packing is too tight, loosen it appropriately. If the valve stem is skewed, notify personnel for repair. Some globe valves experience difficulty in opening when the closing element expands due to heat in the closed state. If opening is necessary at this time, loosen the valve cover threads by half to one turn to relieve valve stem stress, then turn the handwheel.

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