Is there an auxiliary seal in front of the mechanical seal?
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Is there an auxiliary seal in front of the mechanical seal? What kind of seal is it? Is what is shown in this diagram a forward-opening impeller?
It prevents impurity particles in the medium inside the pump from entering the sealing chamber, and allows a small gap to be formed between it and the shaft sleeve, creating a relatively independent sealing chamber that facilitates the control of parameters such as pressure and flow rate within that sealing chamber
The throat bushing is a ring that is usually welded in place; it serves to reduce flow rate. It works in conjunction with the shaft sleeve. I’ve really never seen pumps whose diagrams include information on flushing procedures. If there’s a problem with the bearings, the shaft will wear against the bushing, and that would be disastrous. Generally, it is the bushing that wears out against it, and then these two parts need to be replaced.
The throat bushing is connected to the mouth ring in the same way: it can be fixed with screws, with screws passing through the joint, or by spot welding