FLOW RATES - LITRES PER MINUTE VS
PRESSURE. NON-LINEAR!
When salary earners have no pride or
interest in what they are selling then they are merely salary
receivers. It is disappointing to see how poorly equipped some sales
people are. For example, I needed some PTFE tape to seal up a pipe
thread. The salesman at the local hardware store took on a
distinctly blank look when I asked where they kept the PTFE tape?
' No we don't have that.' he mumbled. Dragging him around to the
plumbing section I pointed it out to him. Never heard of it and
couldn't care less if he lost a sale. Conclusion! The employer merely needs a
body to stand behind the counter at minimum cost.
A young farmer informs me that a
spray-gun he'd purchased from an ag supplier has a nozzle-tip with a
two millimetre hole which according to the salesman 'means 2 litres
per minute.' The worst is that he accepted this statement without
question. Where do they dig up this drivel?
This got me thinking about the
relationship between flow rates and pressure. IF A NOZZLE-TIP
DELIVERS 1 LITRE PER MINUTE AT 1 BAR PRESSURE WILL IT DELIVER 2
LITRES PER MINUTE AT 2 BAR? The
simple fact is this. For a nozzle to double its output the pressure
has to be increased fourfold.
Here's how to do the calculation. You
need to know the flow rate for a nozzle-tip at a specific pressure.
Call this l/min1
and the pressure bar1
Example: Nozzle-tip delivers
1.8 l/min (l/min1)
at 4 bar (bar1).
What will the flow rate be
at 16 bar (bar2)
or 4 times the pressure?
l/min2
@ 16 bar = 1.8 x √
bar2
÷
√
bar1
=
1.8
x √ 16 ÷
√
4 = 1.8 x 4 ÷
2 = 3.6 l/min
Where
√ = square root
Check
out the AITX
8004 VK Conejet on page
38 of the 51 M catalogue.
Here's
the formula again :
l2
= l1
x
√
b2
÷
√ b1
In
the real world the flow rate or the pressure may not be specified.
Tel Natl : 083 289 0327
chemicon@multispray.com
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