We're wanting to put in some irrigation for beds and lawn. The heads on the beds need 1.0 - 2.5bar. The lawn sprinklers are closer to 3.5bar.

We haven't drilled yet, but do have tanks and booster pump that we can fairly easily set the pressure set point. However I would prefer to have to run as few a pumps as possible.

What pump would be required to get 3.5bar at the nozzle from a 60m hole vs a 100m hole? I assume we would also need a particulate filter between the pump and the nozzle?

I know some of the smaller rigs are limited to 3" pumps as well.

Good afternoon @rinners

 

The scenario that you sketched above has two answers:

A] A bigger borehole pump which feeds the sprinklers directly or

B] A smaller borehole pump that feeds the tanks and then the irrigation is done from the tanks via the booster pump.

A Might be expensive in the short run but if you are going for B then the pressure pump will most likely run the whole time that the irrigation is in progress even if ballast pressure tanks are used.

 

Irrigation sprinklers systems also have two pressures one when the system is not operating and one where the system is operating or irrigating and there is a minimum pressure otherwise the sprinkler would not spray as far as rated for or would not popup if it is a popup type of sprinkler.

 

5 hours ago, rinners said:

What pump would be required to get 3.5bar at the nozzle from a 60m hole vs a 100m hole?

The pump can only be selected once you know where the water table lies after the hole is drilled, borehole pumps are rated flow vs depth or head. Read this article https://bwa.co.za/the-borehole-water-journal/2017/5/15/selecting-the-right-borehole-pump

 

5 hours ago, rinners said:

I assume we would also need a particulate filter between the pump and the nozzle?

Yes, most irrigation shops have filters similar to the one pictured with either a mesh filter or a disk filter, for borehole use I prefer to use the disc filter because the pump might pump small rocks and it would damage the mesh of the mesh filter. The better housings can also accommodate pressure gauges to indicate that the filter is blocked and the cap on the bottom of the filter housing can be removed to accommodate a tap for flushing purposes.

There is also these filters that can be used inline 

 

 

5 hours ago, rinners said:

I know some of the smaller rigs are limited to 3" pumps as well.

Yes there are 3" borehole pumps available but the flow rate of the 4" is a bit lower than the 3" borehole pump I do not know why the flow rate of the 4" is lower than the 3" because the area of the 4" pump is almost 44% more.

For comparison have a look at these pumps https://borehole-pumps.co.za/product-category/borehole-pumps/

Kind Regards

GerhardK83