As the name implies, the pressure of the valve refers to the pressure that the valve can withstand, that is, the pressure level of the valve is not lower than the design pressure level of the pipeline. The pressure-bearing direction refers to the closed state of the valve after the valve is applied to the pipeline condition. The arrow direction of the valve body is the recommended pressure-bearing direction. If it is installed incorrectly, the leakage failure of the valve may not close tightly. Generally, it is determined according to the use process or usage conditions. The same direction refers to the pressure-bearing direction (the side with high medium pressure on both sides of the valve gate) and the flow direction, and the opposite direction refers to the pressure-bearing direction (both sides of the valve gate). The side with high medium pressure) is opposite to the flow direction of the medium.
Many valves are directional, such as stop valves, throttle valves, pressure reducing valves, check valves, etc. If they are installed upside down, it will affect the use effect and life (such as throttle valves), or they will not work at all (such as Pressure reducing valve), or even cause danger (such as check valve). Normal valves have direction signs on the valve body; if not, they should be correctly identified according to the working principle of the valve.
The arrow marked on the valve body is the recommended pressure direction of the valve, not the flow direction of the pipeline medium. The valve with two-way sealing function may not be marked with an indicating arrow, or an arrow, because this valve arrow refers to the recommended pressure direction. It is better to have one direction in the left and right or up and down directions. Usually used by the engineering installation company as the medium flow direction to mark the wrong installation, resulting in leakage or even pipeline accidents;
The valve cavity of the globe valve is asymmetrical left and right. The fluid should pass through the valve port from bottom to top, so that the fluid resistance is small (determined by the shape), and the opening is labor-saving (because the medium pressure is upward), and the medium does not press the packing after closing, which is convenient for maintenance . This is the reason why the globe valve cannot be reversed. Other valves also have their own characteristics.
The valve installation location must be convenient for operation; even if the installation is temporarily difficult, it is necessary to consider the long-term work of the operator. It is best to keep the valve handwheel flush with the chest (usually 1.2 meters away from the operating floor), so that it is easier to open and close the valve. The hand wheel of the floor valve should be upwards, not tilted, to avoid awkward operation.
The valve of the wall machine and the equipment should also leave room for the operator to stand. It is necessary to avoid operation on the sky, especially acid and alkali, toxic media, etc., otherwise it is very unsafe.
Do not install the gate valve upside down (that is, the handwheel is down), otherwise the medium will remain in the valve cover space for a long time, which will easily corrode the valve stem, and it is contraindicated by certain process requirements. At the same time, it is extremely inconvenient to replace the packing. The exposed stem gate valve should not be installed underground, otherwise the exposed stem will be corroded due to moisture. When installing the lift check valve, ensure that its valve flap is vertical for flexible lifting. For the swing check valve, ensure that its pin shaft is level during installation to allow flexible swing. The pressure reducing valve should be installed upright on a horizontal pipe, and not inclined in all directions.