self-vent of between bearing pump 1

[rashaa]

Dear all
how we can judge the claim of manufacture about self-venting is true or not in the between bearing pump?
top-top nozzle arrangement can be self-vent ,but when? i saw the pump with TOP-TOP nozzle that is self-vent and other one that isn't.
what about side-side or inline pumps?
i think the side side pumps need vent always.what is your idea?

 

[Artisi]

Self venting means that the volute discharge must be positioned so as not to trap air in the top of the casing. Some end suction top-centre line pumps are self venting by nature of their design- as for inline and side / side how can they be self venting when the inlet and discharge branches are below pump centre line.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[rashaa]

your note was usefull for me Artisi.thank you.
and i have another question.
can we guess the quantity of the vent on the casing?I've seen Between bearing with three vent on casing.is it usual?

 

[Artisi]

I would suggest that the number of vent is a decision made by the pump designer / manufacturer as being adequate to vent the casing.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)