Valve installation should pay attention to the protective measures of centrifugal pump valve installation and selection knowledge

Valve installation should pay attention to the protective measures of centrifugal pump valve installation and selection knowledge

Precautions to be taken when installing valves
When the valve is installed, in order to prevent metal, sand and other foreign bodies from invading the valve and damaging the sealing surface, it is necessary to set the filter and flush valve; In order to maintain the compressed air purification, in front of the valve need to set the oil-water separator, or air filter; To check the working state of the valve during operation, it is necessary to set the instrument and check the valve; In order to maintain the operating temperature, install insulation outside the valve; For the installation after the valve, need to set up a safety valve or check valve; Considering the continuous operation of the valve, convenient for danger, set up a parallel system or bypass system.
1. Protective facilities of check valve:
In ORDER TO PREVENT THE leakage of the check valve or the backflow of the media after failure, resulting in product quality decline, accidents and other adverse consequences, one or two cut-off valves are set before and after the check valve. If two shut-off valves are provided, the check valve can be easily removed for service.
2. Safety valve protection facilities:
Installation method before and after the general do not set the partition valve, only in individual circumstances, can be used. If the medium force contains solid particles, affecting the safety valve can not be closed after take-off, to install a lead-sealed gate valve before and after the safety valve, the gate valve should be in the fully open state, the gate valve and the safety valve directly equipped with a DN20 inspection valve to the atmosphere.
When the relief of wax and other media at room temperature for solid state, or reduced pressure gasification and so that light liquid medium temperature below 0 degrees Celsius, the safety valve needs steam heat.
Safety valve for corrosive media, depending on the corrosion resistance of the valve, consider adding corrosion resistant explosion-proof film at the valve inlet.
Gas safety valve is generally provided with a bypass valve according to its size, as a manual vent.
3. Protection facilities of pressure reducing valve:
Pressure reducing valve installation facilities generally have three forms. Pressure gauges are installed before and after the reducing valve to facilitate the observation of the pressure before and after the valve. There is a fully enclosed safety valve after the valve to prevent the failure of the pressure reducing valve, the valve after the pressure exceeds the normal pressure when the jump, including the valve after the system. The drain pipe is installed in front of the valve to cut off the valve, the main function is to drain the river flushing, some use the trap. The main function of the bypass pipe is when the pressure reducing valve failure, close the pressure reducing valve before and after the cut-off valve, open the bypass valve, manually adjust the flow, play a temporary circulation role, in order to repair the pressure reducing valve or replace the pressure reducing valve.
4. Trap protection facilities:
There are two kinds of traps with bypass pipe and no bypass pipe on the side of the trap, condensate recovery and condensate not recovery payment, discharge and other special requirements of the trap, can be installed in parallel.
The trap with bypass valve is mainly used to discharge a large amount of condensed water when the pipeline starts to run. When SERVICING a TRAP, IT is NOT APPROPRIATE TO DRAIN CONDENSATE THROUGH A BYPASS pipe, which can cause steam to escape into THE RETURN WATER SYSTEM. Under normal circumstances, do not install bypass pipe. Only when the heating temperature is strictly required, the thermal equipment for continuous production should be equipped with bypass pipe
Knowledge of installation and selection of centrifugal pump valve
Inspection of centrifugal pump valve before installation
1. Before installation, the product must be carefully checked to see whether there is a certificate of quality and product instruction, so as to clarify the constant pressure situation when leaving the factory. Locate as close to the platform as possible for inspection and maintenance. Under normal circumstances, the safety valve can not be set before and after the truncation valve to ensure safety and reliability.
2. The safety valve should be vertically installed, should make the medium flow from the bottom up, and to check the perpendicularity of the valve stem population pipe diameter, small should be equal to the inlet pipe diameter of the valve; The DIAMETER OF THE DISCHARGE PIPE SHALL NOT BE LESS THAN THE OUTLET DIAMETER OF THE VALVE, AND THE DISCHARGE PIPE SHALL BE LED OUTSIDE AND INSTALLED WITH a BEND SO THAT THE OUTLET OF THE PIPE is ORIENTED TO a SAFE area.
3. When the safety valve is installed, the diameter of the opening hole should be the same as the nominal diameter of the safety valve when the connection between the safety valve and the equipment and the pipeline is open hole welding. Relief valve pressure relief: when the medium is liquid, generally discharged into the pipeline or closed system; When the medium is gas, generally discharged to the outdoor atmosphere; Generally, the oil and gas medium can be discharged into the atmosphere. The outlet of the relief valve empty pipe should be 3m higher than the surrounding structure, but in the following cases, the closed system should be discharged to ensure safety.
Check whether the valve padding, packing and fasteners (bolts) are suitable for the requirements of the nature of the working medium. The old or used for a long time should be disassembled, dust, sand and other debris must be cleaned with water.
5, check whether the stem and disc open flexibly, whether there is stuck and skew phenomenon. ⑦ *** opening seal, check the sealing degree, the valve flap must be closed tightly.
6, check whether there is any damage to the valve, the thread of the valve is straight and intact. Carefully check whether the valve model and specification meet the drawing requirements.
7, check whether the combination of the valve seat and the valve body is firm, the valve disc and the valve seat, the valve cover and the valve body, the valve stem and the valve disc.
Precautions for valve installation
1. The valve should be installed in a place convenient for operation, maintenance and overhaul. It is forbidden to bury it underground. The valve on the pipe in the direct buried and trench should be equipped with the inspection well room, so as to facilitate the opening, closing and adjustment of the valve. The valve body material is mostly made of cast iron, brittle, so it can not be hit by heavy objects.
2. The valve should be kept closed during installation. For THREADED valves close to the wall, it is often necessary to remove the stem, disc and handwheel to turn. During disassembly, the valve should be removed after twisting the handwheel to keep the valve open.
Ensure that the thread is intact and undamaged, and wrap the thread with hemp, lead oil or PTFE raw material belt. When turning the buckle, it is necessary to use a wrench to jam into the hexagonal valve body at one end of the pipe.
3. When installing flanged valve, pay attention to tighten the connecting bolt along the diagonal direction, and exert even force when twisting to prevent the gasket from deviating or causing deformation and damage to the valve body. When handling the valve, do not allow to throw; When LIFTING AND HOISTING THE VALVE, THE rope SHOULD be tied to the valve body, and it is forbidden to tie to the handwheel, valve stem and flange bolt hole.
Lubricants: Different lubricants are required for different grinding tools.
When using mild steel grinding tools, use oil; When using pig iron grinding tools, kerosene is used as lubricant; When using copper grinding tools, use engine oil, alcohol, or alkaline water (alkaline water is natural alkali, the main ingredients are sodium carbonate and potassium carbonate).