It’s called water method

“The \"water method\" is a way to determine the severity of water shortage or excess water. That is, to determine whether, in the case of water shortage, the water level is only as low as the lower edge of the water gauge’s connecting tube or even lower ； Determine whether, at full water level, the water level is as high as or above the upper edge of the gauge’s steam connection tube. The steps to draw water when there is a water shortage are: open the water discharge valve of the water level gauge, close the steam connection valve of the water level gauge, and then slowly close the water discharge valve. At this time, the pressure inside the level gauge is slightly lower than that inside the steam drum. If the water level reaches only the lower edge of the water connection pipe, the pressure from within the steam drum will force water into the level gauge, resulting in a visible water level in it. If no water level is still visible in the gauge, it indicates that the water level is below the water connection pipe, and it is unknown to what extent it has dropped. The procedure for filling with water is as follows: open the drain valve of the water level gauge and close the water connection valve of the gauge in order to flush the steam connection pipe and the water level gauge itself, and then slowly close the drain valve. At this point, if there is a water level visible in the gauge, it indicates that the water level is only as high as the steam connection pipe; if no level is visible (the gauge is still full of water), it means the water level is higher than the steam connection pipe, though it is not known to what extent. Due to the relatively small water volume in the drum of high-parameter, large-capacity boilers, the water stored in the drum will be vaporized in a very short time, or it will reach a level that is unacceptable. Furthermore, since the elevation of the drum is very high, it is too late for the operators to rush to the drum and use the \"water calling method\" to determine the severity of water shortage or overfilling. Therefore, it is stipulated that during operation, if severe water shortage or severe water overload is detected from the instrument readings, the boiler must be shut down urgently. It is not allowed to use the \"water call method\" to determine the severity before deciding whether to shut down the boiler; instead, the \"water call method\" should be used after an emergency shutdown to assess the severity of water shortage or overfilling. In the event of an emergency shutdown due to severe water shortage, if the water level can be indicated by a gauge using the \"water call method,\" water can be added slowly to restore the water level; once the cause of the incident has been resolved, the system can be restarted by igniting it again. If there is no water level shown in the gauge, it is strictly prohibited to supply water; only after the boiler has cooled down and been inspected can it be determined whether operation can be resumed. For example, when a boiler is said to be at low water level, it means that the water level in the boiler has dropped to such an extent that it can no longer be seen; in this case, the method of checking the water level by sounding is used to determine whether it is below the level indicated by the connecting pipe of the drum water gauge. Method to call for water: Close the valve of the water level gauge ； Water level gauge valve for boiling water ； Open the water valve ； If the water level remains above that in the water level gauge connected to the water measurement tube, then the water level will rise under the pressure of the steam drum.