Suggest you sketch out a typical open system and a closed system and look at what is different between them - then think about how a pump would operate on each system. It's a fairly basic concept - once you understand the differences, come back and we can discuss the operation of each system.
Of course you have searched the net for open and closed pumping systems, yes?

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.)

In a closed system the pipe's end pressure = suction pressure of the pump.

At a basic level Open system the pump discharge head is friction plus maximum ststic head.. Closed system its only friction of the entire loop providing you have a positive pressure at the highest point.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

A simple and effective way to understand the difference and practical application by reading this book:
https://www.routledge.com/Building-Services-Handbo...

* Finding a solution is great * Knowing how to implement it is fantastic * Believing it is the only one and best is naive ?

BenMacier, like your tag - wise words.

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.)