The way the check valve works is when the flow is in its direction, the flow rate will pass through the disk or plug, while when there is an opposite flow, the plug will be closed, so that no backflow will enter into the pipe. Therefore the existence of this check valve is very important, so do not get left behind when you draft a design
Use of check valve in the hydrant installation is often encountered in the pump system circuit. The order of installation is Flexible Join> Check Valve> Gate Valve. This sequence should be appropriate and the installation of the check valve should not be upside down, the direction of the arrow should face up. If reversed then the direction of the water flow is closed and may result in the outbreak of the check valve itself or even all pipelines