Thats about right laurapasinifan. I found results were closer to double the flow rate between 1/2 and 3/4 inch pipe so I would have estimated 3 gpm.
The problem is
-lots of tight bends restrict the flow.
- The inlet and outlet diameter is often constricted eg 1/2 inch outlet from tinaco
- the flow is likely restricted by a non-return valve
All these factors penalise the flow rate so there really is no way to tell except to have a doctorate in fluid dynamics or have a go
Perhaps experiment with some cheap black poly pipe first.
Are we getting close to an answer for you Bob?
an update and other question
was at a friends house in Hato Mayor the other day,and was discussing the flow question I had.He took me up to his tinaco,and showed me what he had done...he has a 1inch pipe out of tinaco,down the side of house,then goes into a 1/2 inch pipe.He has great pressure.I have not purchased the pump yet,so I will try this first...
the question I have is...He also has a pipe directly out of outlet of tinacoat at a T, that goes straight up,just above tinaco height and is open......what is that for???
bob