Locate the indicator where the operator can easily see it. The indicator must show either pressure or flow. DO NOT install the indicator between the enclosure and protective gas supply DO NOT connect valves between the indicator and the enclosure The protective gas supply shall have an alarm located in a constantly attended area and fulfill requirements in NFPA 496 section 4.3.2.

Requirements For Disconnects
The disconnect switch immediately cuts off power to the enclosure when pressure drops below a safe level. This switching is required for Type X systems. It can also be used in Type Y and Z systems.

Exceptions to the disconnect rule for Type X systems: In some instances, a power loss represents a greater hazard than operating the system under low pressure. An alarm is acceptable in these circumstances, but only for a short time, and special requirements may be necessary.

Requirements for disconnect switches

• Must be actuated by the protective gas flow rate or the differential pressure inside the enclosure
• Must be approved for its location
• DO NOT connect valves between the disconnect switch and the enclosure
• Shall take its signal from the protected enclosure
• DO NOT install between the enclosure and the protective gas supply. Refer to NFPA 496 section 4.10.1 for more information.

Protected Enclosure Device Details

Protected Gas Supply Alarm Details