[APD] Re: Help! (Flowgauge Regulator)

["Douglas Guynn" <d_guynn at sbcglobal.net>]

Rick wrote:
	"Does anyone know what the difference is between this and a standard
regulator and, more importantly, if it matters?  If the recommendation is to
set the pressure to 10 to 20 PSI, how would that equate to CFH?"

A standard pressure regulator will allow enough fluid (in our case gaseous
CO2) to pass through to maintain a specific outlet pressure, irrespective of
flow (within the operating parameters of the regulator). In this
application, you open the downstream needle valve, the regulator will open
enough to maintain the tubing between the regulator and the needle valve at
the chosen pressure. Some of these are adjustable, some are preset.

I believe the "regulator" you purchased is actually a flow control device,
not a pressure control device. It will allow enough fluid (again, CO2) to
pass through to maintain a specific flow, irrespective of pressure (again,
within the operating parameters of the regulator). Of course, this depends
upon whether or not the downstream equipment will accept the set flow rate.
If not, the pressure will continue to rise to whatever the maximum outlet
pressure of the "regulator" is.

You cannot convert psi to cfm, unless the system is stable. For instance; if
the orifice size does not change, and the inlet and outlet pressures do not
change, and the composition of the fluid does not change, and the
temperature of the system does not change, the flow will remain constant. If
any one of the variables change, it will affect the flow rate. If two of the
variables change, the flow may or may not change, depending which variable
changes and whether it increases or decreases.

While pressure and flow are related (flow is, after all volume per unit
time), to compare them is like comparing oranges to apples. They are both
fruit (related), but definitely nowhere near the same (interchangeable).


Douglas Guynn
	432.368.5411
	d_guynn at sbcglobal.net

"The power to do things for you is the power to do things to you." - Dorothy
Parker

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