What pressure is a second stage regulator set at?

What pressure is a second stage regulator set at?

• A. 5 inches of water
• B. 11 inches WC
• C. 15 inches WC
• D. 20 inches WC

Answer: (B)

The main idea is that a second stage regulator provides the user with a low, comfortable breathing pressure after the first stage drops the supply to an intermediate level. For many two-stage breathing-air systems, the second stage is set to about 11 inches of water column. That’s roughly 0.39 psi, a pressure low enough to be comfortable for breathing yet high enough to deliver sufficient flow during inhalation as demand changes. If it were much lower (like 5 inches WC), the flow could fall off during deeper breaths; if it were much higher (15 or 20 inches WC), breathing would feel stiff and could cause regulator or system issues.

The main idea is that a second stage regulator provides the user with a low, comfortable breathing pressure after the first stage drops the supply to an intermediate level. For many two-stage breathing-air systems, the second stage is set to about 11 inches of water column. That’s roughly 0.39 psi, a pressure low enough to be comfortable for breathing yet high enough to deliver sufficient flow during inhalation as demand changes. If it were much lower (like 5 inches WC), the flow could fall off during deeper breaths; if it were much higher (15 or 20 inches WC), breathing would feel stiff and could cause regulator or system issues.