Flow rate of fitting too great for supply flow rate.

[PleaseDontLeak]

I'm attempting to size a new domestic system, and I'm using this PDF from Copper Plumbing. In it, it states that a 1/2 " washing tap has a recommended flow rate of 0.2 litres per second, so 12 litres per minute. According to my supplier, they guarantee 10m head and a flow rate of 9 litres per minute. Two questions please:

1) How is it my supplier can't even guarantee I can turn on a 1/2 inch washing tap and get the full flow rate?

2) Also, a guarantee of 10m head doesn't appear to be anything at all. Using that PDF, if I had a 22mm pipe with an equivalent length (pipe + fittings) of 30m, I'd only have a permissable head loss of 0.333 (10m / 30m). So using the nice big chart on the second page of the PDF I would at a push manage 0.2 litres per second, leaving no residual head at all!

What am I doing wrong here???

 

[Agile]

You are expecting too much.

Also in the UK we are accustomed to quoting flow rates in li/min!