Plumbing Forum | Plumbers Forums | A forum for plumbers in the UK - View Single Post - please help as im confused on a certain question?

Alanka · 26-05-2008

It is confusing isn't it!

The pressure exerted by water at the bottom of a vessel depends ONLY on the depth, not the volume or any other tank dimensions. So the pressure at the bottom of a 1m long vertical 15mm pipe full of water is exactly the same as the pressure at the bottom of a swimming pool at the 1m end: that is 9.81kN/m2 (9.81kPa)

1 metre of water depth exerts a pressure of 9.81kN/m2 (9.81kPa, about 0.1bar). So 1.6m depth exerts a pressure of 1.6 x 9.81kN/m2 = 15.70kN/m2 (15.70kPa).

So your first calculation is the correct one!

(A rough guide is that 1 atmosphere, i.e. 1 bar, or 100kPa, equals about 10m of water head.)

26-05-2008	#2 (permalink)
Alanka Member Join Date: May 2008 Posts: 54	Re: please help as im confused on a certain question? It is confusing isn't it! The pressure exerted by water at the bottom of a vessel depends ONLY on the depth, not the volume or any other tank dimensions. So the pressure at the bottom of a 1m long vertical 15mm pipe full of water is exactly the same as the pressure at the bottom of a swimming pool at the 1m end: that is 9.81kN/m2 (9.81kPa) 1 metre of water depth exerts a pressure of 9.81kN/m2 (9.81kPa, about 0.1bar). So 1.6m depth exerts a pressure of 1.6 x 9.81kN/m2 = 15.70kN/m2 (15.70kPa). So your first calculation is the correct one! (A rough guide is that 1 atmosphere, i.e. 1 bar, or 100kPa, equals about 10m of water head.)
Alanka Member Join Date: May 2008 Posts: 54	Cheers, Big Al Last edited by Alanka; 26-05-2008 at 11:41 AM. Reason: Further thought