Responding to inaccurate Forum comment about
pressure drop in MIG shielding gas hose:
First lets set the record
straight. Your setting flow NOT pressure on your MIG flow
meter even on a regulator/flowmeter (Pic Right.) Look carefully and
you'll see the output gauge says CFH NOT psi. What does that
mean? CFH stands for Cubic Feet per Hour. That is what your
setting. Pressure is measured in Pounds per Square Inch.
A point of confusion on
hose size may be from what is needed with an air compressor.
Even a small one may be rated at 10 CFM and does need a large hose!
That stands for Cubic Feet per Minute! So even a small air compressor
can flow 10CFM x 60min/hr or 600CFH!! Sure at that flow rate you
need a big hose! But not at the 25 to 30 CFH we use in welding.
That is only 1/2 CFM! Pretty low flow. In fact that is about the
amount your breathing. Anything more and your just pulling air into
the gas stream!
At 25 CFH flow rate with
a 30 foot
GSS
hose there will be about a 3 psi pressure drop. If your using a
regulator/flowmeter like the one in the picture you'll have plenty of excess
pressure. I'll explain how the system works so you'll see why:
With a
regulator/flowmeter you are actually setting pressure! Your setting
the pressure above a very small orifice in the outlet of the regulator.
Typically it is about 0.025 inches. It takes about 40 psi above the
small orifice to flow 25 CFH. Why do they have such high pressure?
So the flow will be constant when spatter builds in the torch, as you bend
the torch cable.
Typically the pressure needed at the inlet to a
welder/feeder is 3 to 7 psi. By having about 40 psi above the small
orifice the flow will remain at the flow you set.
(SEE
Automatic Flow Compensation if you want to know how that works.)
If you put a
pressure gauge between the welder/feeder and the gas delivery hose you'll
measure about that 3 to 5 psi when your welding. However when welding
stops, gas will still flow through the small orifice and will rise quickly to the 40
psi regulator pressure. That creates the big surge of gas at the weld start
which is what our
GSS
eliminates!
Now if you read about
Automatic Flow Compensation you found out you needed about twice the
pressure above that small orifice compared to below it to achieve that constant flow (all
pressures measured a absolute pressure.) With 30 feet of our
GSS
hose with its 3 psi
pressure drop you have more than sufficient pressure with 40 psi to achieve constant
flow.
Probably just provided more
information than you
wanted to know but if you have any questions Email:
TechSupport@NetWelding.com