xavierjevon

Let me clarify even further. A Cylinder with 2 Cubic Meters of Gas, at 150 Bar Pressure, needs the regulator set at what in order to get an initial flow of 15 liters per minute?

Let me make clear that I understand everything you are saying about the DROP in pressure, and how the fluctuation works. But that still doesn't mean the question of INITIAL FLOW RATE cannot be answered. "In the same way a pressure regulator regulates pressure which is not measured in litres per minute." And this is expressly incorrect. Balloon Helium Gas Manufacturers, for example, speak about litres per minute as flow rate in order to make sure that there is a tempering on the amount of gas coming out so that balloons can be filled easily.

"What speed do I need on my speedometer to drive 50 miles?" This is very simple. If the speedometer was reading in KILOMETERS and not in miles... and someone asked, "What speed do I need the speedometer at to drive at 50 miles an hour?" That is a legitimate question. In the same way, for a regulator that does not list itself in terms of liters per minute, to ask, what should the setting be to at least get an INITIAL flow of 15 litres per minute? Is a valid question. There is no need to avoid this question. If you don't know, say you don't know, guys.

From my understanding, I am sure you can. There is lots of explanation and talk about setting a regulator so that it releases pressure at a certain level. Maybe it requires a double-stage regulator in order to achieve this... But at the very least, even though the cylinder pressure is going to decrease over time, as a starting point, you can still set a regulator at a particular setting so that it BEGINS at releasing 15 L per minute. That question can be answered.

Actually, I would like to understand this too. I think what phdinfunk is asking is a specific answer - "I'm pumping gas from 150 Bar to Atmospheric Pressure. What pressure does the regulator need to be set at in order to get 15 Liters per minute as my flow rate?" What should the regulator setting be for this?