What is the general operating pressure range for the Low Pressure Line?

What is the general operating pressure range for the Low Pressure Line?

• A. 75-100 psi
• B. 60-120 psi
• C. 100-150 psi
• D. 85-165 psi

Answer: (D)

Think about how air is delivered in an SCBA. After the cylinder air is reduced to a usable intermediate pressure, that pressure feeds the rest of the system through the low-pressure line to the second stage and the facepiece. The system must work whether the cylinder is full or nearly empty, so the line’s pressure isn’t fixed; it varies with cylinder fill and regulator design. That intermediate-pressure range is typically about 85 to 165 psi, which allows the regulator to deliver a steady breathing flow to the mask across different conditions. So the general operating range for the low-pressure line is 85-165 psi.

Think about how air is delivered in an SCBA. After the cylinder air is reduced to a usable intermediate pressure, that pressure feeds the rest of the system through the low-pressure line to the second stage and the facepiece. The system must work whether the cylinder is full or nearly empty, so the line’s pressure isn’t fixed; it varies with cylinder fill and regulator design. That intermediate-pressure range is typically about 85 to 165 psi, which allows the regulator to deliver a steady breathing flow to the mask across different conditions. So the general operating range for the low-pressure line is 85-165 psi.