Mark Allen wrote:

You're right Al - great test questions.

 

Let me add a bit more - 

 

On the low oxygen concentration it's a bit more complex.  Each train has to have a concentration monitor.  If oxygen falls to <91%, the train in question must be automatically closed off from the system to prevent contamination downstream.  The Supply Source Isolating Valve is BOTH manual and Automatic for this reason. That is unique to NFPA - it was not part of the ISO document.

 

Your reading of the alarms is also correct - there are a LOT of them.  Because each train is equipped with a manual/automatic valve, the valve itself must be provided with an signal (5.1.3.5.11.12 (5)).  If you close the valve manually, it will give an alarm e.g. "Oxygen Concentrator Supply Source Isolated" signal.  This is a Master alarm signal only - unusually it is not Local and Master, which is because Locally you will be able to physically look at the valve.  If oxygen falls below 91%, the alarm e.g. "Low Oxygen Concentration, Oxygen Concentrator Supply Source X" will be activated at Local and Master panels AND because the Supply Source valve will close automatically, the "Oxygen Concentrator Supply Source Isolated" alarm at the Master will ALSO be activated.    

 

I've not updated my "Oxygen On Site" booklet yet, but I'll try to make the alarms clear when I do.  It's not a classic sequence like we are used to.

All the comments about this subject have been grate

I want your opinion about the vale requirement that has to be both manual/automatic, at the end of last year I was verifying a O2 producer  and it did not have one vale with the two functions, it has one manual valve and one automatic valve, the automatic was able to activated the local and master alarm signal but the manual did not, how ever this system had a flowmeter unit that also was able to activate the automatic valve and the signals, so if any one close the manual valve the flowmeter unit was able to sense that the generator was isolated and in a sense it could notice that the manual valve was manually close and that the oxygen concentrator was isolated and activated the master alarm signal.

Could you think that this arrangement accomplish the goal of the both manual and automatic valve and signals?

Jose:  Although the standard speaks of one valve, I think you can fully meet the intent with two valves.

However, you need to fully meet the intent - if you can close the manual valve and not get an alarm, I think there is a problem, as the standard mentions the alarm must signal when the valve is either manually or automatically actuated. 

The flowmeter and other modes of control are up to the manufacturer.  Some concentrators will benefit from/require these additional controls, but they are not required under the 99, so they fall under the "may always exceed the standard" rule.

 

Don:  While I'm pleased you have had good luck wth your installations, should we not avoid product endorsements in the Forum? 

Don pointed out the list of signals for the Master Alarms and Local Alarms in the Annex in Tables A.5.1.9.2 and A.5.1.9.5.  There certainly are a lot of signals and it helped me to identify them in the code text.  However, the original proposals called for High Concentration alarms that did not make it into the final version.  This was intended to alarm when the concentration was above 95% when producing Oxygen 93 USP.  

The following paragraphs do not exist  in the code or do not reference the high concentration signal mentioned:  5.1.3.5.11.13(3), 5.1.9.5.4(13)(f), 5.1.9.2.4(14)(h).

You may want to cross out the signals labeled Oxygen Main Line High Concentration in both tables and Oxygen Concentrator High Concentration in the Local Alarms.