Document No. 32014-68 issued by the Chief Safety Officer: Liquid level in tank areas
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Alarms are provided for high and low liquid levels in the storage tank; the feed valve is automatically shut off when the liquid level is too high, and material delivery is stopped automatically when the liquid level is too low. Why is it necessary to install a feed valve for such an extremely high liquid level? Can’t the feed pump simply be stopped?
A feed emergency shut-off valve must be installed. The feed pump has stopped, and sometimes the feed tank builds up pressure; even when the pump is off, the material still presses forward.
Is that feed valve installed behind the feed pump, on the side of the tank’s feed inlet? Then does the excess liquid level automatically close the valve to stop the feed pump?
Yes, it’s installed right at the inlet of the storage tank.
It depends on the height of the feed source and the liquid level in the tank. If the height of the feed source is higher than that of the tank’s liquid level, the pump will stop, but liquid can still enter the tank through the impeller.
This valve has another purpose as well: it serves as an emergency shut-off valve for the seats in case of other accidents, and it is not just a high liquid level interlock valve.