Pumps with dry gas seals cannot achieve sufficient flow rate
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I have a pump with a dry gas seal in a negative pressure system; it doesn’t deliver flow at startup and requires repeated exhaust operations – how can this be resolved?
Is the dry gas seal system Plan74?
With 30 tons, it shouldn’t be impossible to start the machine due to air leaking in through the dry gas seal; try starting it by slightly opening the outlet valve.
If there is a check valve at the outlet, and the check valve has a bypass line, then open the bypass line. It’s also unclear how high the liquid level can reach at the pump inlet, and whether there is a saturated vapor phase above the liquid surface. If there is a saturated vapor phase, it’s necessary to determine the height of the liquid level above the centerline of the pump inlet, to see if it exceeds the required NPSH for the pump. It’s not so large that it will prevent the car from starting.
In theory, there should be no problem, but in practice, repeated exhausting is required to increase the volume
All various methods, including those you mentioned – with the exhaust line and outlet valve open – don’t work either.
What type of medium does your pump use? We encountered a problem on site earlier with a methanol-poor flow pump: due to a leak in the dry gas seal, nitrogen entered the pump, causing cavitation and preventing it from starting