Another poster on this forum couldn't understand why a difference in 2mm hose size (8mm minibore to 6mm microbore) should make a difference in flow. Doug Atkinson from Daqua posted this in reply
It does -------, makes at least 30% reduction in flow
Take a look at this;
http://www.flourmilling.co.uk/water.htmlI realise its steel pipe but I see the flow rate difference between 6mm and 8mm bore steel pipe is considerable. At 4 bar the flow through 6mm pipe is 0.022 liters per second. The 8mm pipe its 0.056 liters per sec at the same pressure. So a 6mm tube will only allow fractionally less than 1/2 the volume of water at 4 bar. Our hose coiled up around a hose reel will probably reduce those figures a bit more.
Hot water will have a higher (or is it lower) viscosity (less dense) so will flow better through a smaller diamt hose. So most hot water users happily use microbore hose.
http://www.frca.co.uk/Documents/100308%20Physics%20of%20flowLR.pdfInteresting read these 7 pages.
Look at the difference between Laminar flow and Turbulent flow. Once fluid in a tube reaches a certain speed it become turbulent. Once it becomes turbulent it requires 4 times the amount of pressure to double the flow rate. Fluid through hose coiled on hose reels won't be laminar in flow but turbulent.
To calculate the area of a circle the formula is
A = π r2
A 6mm id hose is fractionally more than half the size of an 8mm hose.
A 3mm jet is a little more than twice the size of a 2mm jet.
A 1mm jet is about 1/4 of the size of a 2mm jet.