Why is it necessary to turn off the cold pump line after starting the centrifugal pump? It’s okay if it’s not related, right?
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Problems with centrifugal pumps in low-temperature methanol washing
There’s no need to turn it off; ours stays on all the time, otherwise when the backup pump starts up, the gas will vaporize instantly
Our leader said that before starting the backup centrifugal pump, it’s necessary to turn off the cold pump line… He also asked us to think about why, and after some consideration we felt that it might not matter whether we turn it off or not
The cold pump line generally needs to be turned off before startup, as the pump must be depressurized before it is started. Failing to close the cold pump valve can create an illusion of depressurization, which makes it easier for air to accumulate in the pump and lead to air lock. Once startup is normal, the cold pump line should be turned on. Stay in cold standby.
The cold pump line of the centrifugal pump remains connected when it is in standby mode, in order to maintain the pump’s operating temperature at low levels and prevent thermal flashing of the cold liquid. Before starting the pump, it is necessary to close the cold pump valve and vent the air first, before proceeding with the pump startup procedure.
Since the exhaust valve needs to be closed before starting the pump, isn’t it unnecessary to open the cold pump valve after the pump has started?
Either is fine; the cold pump circuit of a standby pump is usually left on, and there’s no time to turn it off when the standby pump starts automatically