The sampling valve is often used for chemical analysis of medium samples, so it is very important to maintain the sampling valve daily, because the damage of the pneumatic Sanitary sampling valve in the operation is very great.
How to maintain sampling valve？
How to repair a damaged valve?
How to maintain sampling valve？
1. Sampling valves that have been stored for a long time should be checked regularly, and exposed machining surfaces should be kept clean to remove dirt. The pneumatic Sanitary sampling valve should be stored in a dry and ventilated place. Piling up or storage in the open air is strictly prohibited.
2. Before installation, it is necessary to carefully check the pressure of the pneumatic Sanitary sampling valve mark and whether the size conforms to the use requirements to avoid the defects caused by the transportation process and eliminate the dirt of the valve parts.
3. During installation, the sampling valve can be connected directly to the pipe line. Under normal circumstances, it can be installed in any position of the pipeline, but it should be easy to operate the overhaul, pay attention to the flow of the globe valve medium should be under the vertical disc upstream.
4. Stem threads are often rubbed against stem nuts and need to be lubricated with yellow dry oil, molybdenum disulfide or graphite powder. Not often open and close the pneumatic Sanitary sampling valve, also want to turn the handwheel regularly, add lubricant to the stem thread, in order to prevent stuck.
5. The problem of how much grease is often ignored when filling sampling valves with grease. After filling with grease gun, operators select the connection mode between sampling valve and grease and conduct the grease operation. There are two situations:
On the one hand, less fat injection leads to insufficient fat injection, sealing surface due to the lack of lubricant and accelerated wear. On the other hand, excessive fat injection leads to waste. The reason is that there is no accurate calculation of different pneumatic Sanitary sampling valve sealing capacity according to sampling valve type and category. The sealing capacity can be calculated according to sampling valve size and type, and reasonable amount of grease can be injected.
How to repair a damaged valve?
1. Leakage of pneumatic Sanitary sampling valve body and bonnet
(1) Improve casting quality, and conduct strength test in strict accordance with regulations before installation.
(2) For the temperature in 0℃ and below the sampling valve, heat preservation or mix, stop the use of the valve should be removed water.
(3) The weld of the sampling valve body and bonnet composed of welding shall be conducted in accordance with the relevant welding procedures, and flaw detection and strength test shall be conducted after welding.
(4) Heavy objects are not allowed to be piled up on the pneumatic Sanitary sampling valve, and hammer against cast iron and non-metallic valves are not allowed. The installation of large-diameter sampling valves should be supported.
2. Leakage at the joint of the seal ring
(1) The leakage at the rolling part of the sealing ring should be injected with adhesive or fixed by re-rolling.
(2) The sealing ring shall be rewelded according to welding specifications. If the surfacing spot cannot be repaired, the original surfacing layer shall be removed and rewelded and processed.
(3) Remove screws and pressure rings for cleaning, replace damaged parts, grind the sealing surface and connection seat, and reassemble. The corroded parts can be repaired by welding or bonding.
(4) The joint surface of the sealing ring is corroded. It can be repaired by grinding, bonding and welding. If it cannot be repaired, the sealing ring should be replaced.
3. The closing part falls off and leaks
(1) Correct operation: close the pneumatic Sanitary sampling valve without excessive force and open the valve without exceeding the upper dead point. After the pneumatic Sanitary sampling valve is fully opened, the handwheel should be reversed a little.
(2) The connection between the closing part and the sampling valve stem should be firm, and there should be a non-return part at the threaded connection.
(3) Fasteners used to connect the shutoff parts to the stem shall be resistant to corrosion by the medium and shall have certain mechanical strength and wear resistance.
The maintenance of the sampling valve is very important. Only good maintenance of the valve can ensure its working efficiency. If the pneumatic Sanitary sampling valve is damaged, you should know how to repair it to minimize the loss.
