Currently we are designing the CO2 Fire Suppression System for the MMCC Power Plant in Malaysia.
I would like to seek clarification on the NFPA 12 Clause 4.5.5 Supervision and Lockout Valves.
As per NFPA 12 : Clause 220.127.116.11 – Supervision of automatic system and manual lockout valves shall be provided unless specifically waived by the authority having jurisdiction (AHJ).
Lockout valves will be required for compliance to NFPA 12 as part of the various safety requirements for protected areas that persons could occupy. There are also other requirements such as pneumatic alarms, pneumatic tune delays, etc.
However, in Malaysia, all CO2 Fire Suppression System only require a Manual Isolation Switch / Maintenance Switch with sufficient alarm, graphic warning signs and using the local AHJ (Malaysia Fire & Rescue Department) approved CO2 Fire Extinguishing Panel and Devices as per the local AHJ.
Lockout valves and Manual Isolation Switch / Maintenance Switch are both mechanisms which allow for deactivation of automatic discharge of a fire suppression system when it is in the maintenance mode. The reasons for selecting either of these devices as part of a tool for fire suppression system and provide a proper method for installing these devices in a fire suppression system design that complies with applicable fire codes and industry guidelines.
Based on our local AHJ (Malaysia Fire & Rescue Department) requirement, the CO2 System design criteria shall follows applicable local fire codes where the system is designed with a “Double Knock System using a Smoke and Heat Detector and with the required safety factor guideline, provision of Manual Isolation Switch / Maintenance Switch with sufficient alarm, graphic warning signs and using the local AHJ (Malaysia Fire & Rescue Department) approved CO2 Fire Extinguishing Panel and Devices as per the local AHJ.
The CO2 Fire Suppression System shall be designed by a qualified fire safety expert and substantiated with Hydraulic software calculation. However, our local AHJ (Malaysia Fire & Rescue Department) rarely suggests the use of lockout valves for the CO2 Fire Suppression Systems.
The basic reasons for the CO2 Fire Suppression System design that complies with applicable fire codes in Malaysia as per the fire safety system design is as follows :-
- No fire codes or industry standards require utilization of a lockout valve in a fire suppression system.
- A Manual Isolation Switch / Maintenance Switch functions as reliably and robustly as does a lockout valve, in providing the basic safety function of disabling the discharge capability of a fire suppression system during maintenance.
- A lockout valve requires secondary components to be installed, in order to comply with applicable codes, specifically: pressure switches and pressure relief valves. (Pressure switches and pressure relief valves are required by code to be present when a lockout valve is installed.)
Appreciate your confirmation on the above.