No. It doesn't work like that. Matheson wrote a simple explanation about single and two stage regulators.
TWO STAGE regulators reduce the source pressure down to the desired delivery pressure in two steps. Each stage consists of a spring, diaphragm, and control valve. The first stage reduces the inlet pressure to about three times the maximum working pressure. The final pressure reduction occurs in the second stage. The advantage of a dual stage regulator is its ability to deliver a constant pressure, even with a decrease in inlet pressure. For example, as a cylinder of gas is depleted, the cylinder pressure drops. Under these conditions, single stage regulators exhibit a “decaying inlet characteristic”; where the delivery pressure increases as a result of the decrease in inlet pressure. In a two stage regulator, the second stage compensates for this increase, providing a constant delivery pressure regardless of inlet pressure conditions. The dual stage regulator is recommended for applications where a continuous supply of gas is required; such as the gas supplied to analytical instruments where constant delivery pressure is critical.
SINGLE STAGE regulators perform the same function as the two stage regulator using a single step reduction of source to outlet pressure. For this reason, the outlet pressure cannot be as accurately controlled as the source pressure decays. We highly recommend single stage regulators only be used in circumstances where the operator can monitor and adjust the regulator as needed or where the regulator is supplied a nearly constant source pressure.
