Why would flow rate through a regulator increase steadily?

[DBTKNL]

I am trying to make sense of the way my Swagelok RSH10 pressure regulator behaves. Its inlet is connected to a bank of 10 parallely connected nitrogen gas cylinders each at 150 bar. As the inlet pressure decreases, for a set outlet pressure of 10 bar, the flow rate steadily increases at a rate of about 100 Nm3/hr (Normal meter cube per hour)  per minute.

I am aware of the "dependency" phenomenon in regulators where the outlet pressure increases with decrease in inlet pressure. Why is the effect so profound?

 

[zdas04]

Have you ever allowed the system to go down until the tanks are around 25-30 bar? If so, is the rate still accelerating or did it steady out and start to fall off (that is a really large acceleration rate, that would have to be pipe limited pretty early in the process)? Is it maintaining the downstream pressure at 10 bar (i.e. where is the gas going that it can tolerate the accelerating flow rate)?

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[DBTKNL]

Yes I have gone down to about 20 bar. The same trend follows.

The flow is directed towards a nozzle where the flow is supposed to be choked. But this trend has left me confused.