CO2 cylinder valve - function of the "push button/cap" 1

[shlim]

Dear all,

I hope this is the relevant site to post my question. Please re-direct me if there is a better channel in this forum.

I came across a CO2 fire suppression system, which had been claimed to have been activated after a small fire inside an electrical room.

1. The pressure gauge for the pilot bottle was at 1000psi (half of the maximum scale of 2000psi). I expect that the pilot bottle would be empty if it was activated. Could be it due to leak?

2. 3 out of 11 main co2 cylinders did not have a "cap" on the cylinder head (see attached photo). Red circle shows no "cap"; white circles show cylinder valves with "cap" attached. What is the function of the "cap"? The word "push" was written on the cap.


Thank you.

 

[stookeyfpe]

In response to your Question 2, the cap is used to actuate the manual release valve on the CO2 system. These are allowed when the CO2 system is designed for manual activation.

Regarding Question 1, the gauge malfunctioned because it should be at zero, based on your statement.

Based on this photo is that I suspect the system hasn't been inspected since the day it was placed in service. I base this assumption on condition of the hoses and valves. It appears highly unlikely that the cylinders haven't been weighed to confirm that CO2 hasn't been lost because of a small leak around the valve and the hoses haven't been subjected to the 5 year pressure test required by NFPA 11.

 

[shlim]

Hi @stookeyfpe, your comments are much appreciated.

Thank you for the clarification regarding the function of the cap. I was wondering whether it was a safety cap that prevented activation during installation; and it should be removed when the system is in operational mode (so that it could be triggered).

 

[stookeyfpe]

Shlim:

The device circled in the photograph is not a safety cap - it's a knob. It's provided to allow a person to depress the valve stem and discharge CO2. Such an arrangement should have a permanent sign instructing plant personnel or tenants that in the event of a fire that all of the emergency knobs should be depressed. This is necessary so the required design concentration is discharged into the space being protected.

The knob is a manual release so if none of them were operated, this indicates that the system was not operated manually. I would conclude that either

a) the automatic fire detection system, if provided, failed to either respond to the fire because the heat release rate or smoke production rate was below detection limits,
b) the automatic fire detection system, if provided, failed for other reasons, or
c) it's a manually activated system and plant operators or building tenants didn't know how to operate the system.

A definitive method is available to determine if the system operated: measure the weight of the cylinders, open the valve of one cylinder and relieve the contents, and compare the difference. You may open the valve and find that they one or all are empty.