Date: Thu, 8 Jul 2010 15:47:19 -0500
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Tsiakals, Nicholas John" <tsiakals**At_Symbol_Here**ILLINOIS.EDU>
In-Reply-To: <4C35CACE.8648.0091.0**At_Symbol_Here**>

Thanks for the clarification, Eric.  Goes to show, there's usually a lot of
 information behind each of our comments!  And it's a good point about brev
ity and PE certification.

For my part, I find the detection questions interesting if not downright di
fficult at times.  I also find the notion of "over-control" quite interesti
ng.  In my context I find several varieties of blind over-control, not to m
ention blind under-control.  Removing "unnecessary" hoods from service and 
drawing license from safety features on customized equipment come to mind. 
 I think there's an old proverb to not remove a fence unless you know why i
t's there.  That's the trick - to know why it's there!

All the best,

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of Er
ic Clark
Sent: Thursday, July 08, 2010 2:54 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU

Thanks for the thorough email, Nick.  
I should probably comment on your implication that this lab might blindly j
ump to over-controlled solutions without regard to justification.  Excellen
t point.  We considered many options but I only mentioned the end solution 
that worked for us:  Install the O2 sensor (Enmet Model ISA-40M).  I should
 also mention that the particular room is a terbuculosis lab with many bios
afety regulations attached to its operation - e.g. you can't just vent the 
unfiltered TB lab air outside.  For this situation, if a CO2 line leaks and
 the oxygen level goes low, the horn honks; and you can easily test the uni
t by holding your breath for 10 seconds and exhaling on the sensor (codifie
d on page 10 on the maintenance manual).  It's the same reason people put l
ow-oxygen sensors in wine cellars - so when the butler goes down to get win
e he'll come up again.  Of course for brevity's sake my email to Vic was on
ly three lines long, and Vic's a professional engineer.  Thanks for the opp
ortunity to clarify.  Eric 

>>> "Tsiakals, Nicholas John"  7/8/2010 8:55 AM >>>
This may be more than you're looking for, but here goes:

"Just install the detection system" might sound like a good / prudent thing
 to do, but there are some drawbacks.  With the information on the table, I
 would put "Just install it" under the "blindly over-controlled" column.  (
By "blind" I mean "blind with respect to what is strictly necessary" or "bl
ind w.r.t. how much control is enough control".)  Be aware that when bills 
come due and money gets tight, decision-makers can very easily cut the inst
allation or maintenance costs on such systems - where's the justification? 

So the challenge is to develop a good understanding of what is an acceptabl
e risk:  What control measures are necessary to sufficiently control the ha
zard?  Where is "the line", and how far beyond the line should we be?  A mo
re robust rationale than "it's easy enough to do" is to run reasonable scen
arios to describe the risk in the current scheme.  What would it take to de
velop an Oxygen Deficient Condition at any one of these utility stations?  
At any neighboring offices?  How likely is such a scenario?  For instance, 
if you know it would require a very noticeable (think: loud) leak for 20 mi
n in a busy hallway, then you may reasonably conclude a detection/alarm sys
tem would be overly redundant.  On the other hand, if a small bleed could r
esult in an ODH at a desk, then the detection/alarm system would seem very 

Recognize that an alarm system is an administrative control.  What action d
oes it call for someone to perform?  If the detection system is connected t
o emergency ventilation or shut-offs, now we are talking engineering contro
ls.  So I would urge you to work forward through the hierarchy of controls:
  elimination - substitution - engineering controls - administrative contro
ls - personal protective equipment.  Are there design phase (engineering co
ntrol) solutions which make the administrative control unnecessary? 

A principal question here is, "If there were a problem, how would you know?
" followed by, "How likely is it that a problem occurs?"

Hope this helps,

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of Er
ic Clark
Sent: Thursday, July 08, 2010 10:02 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU 

Consider installing a low oxygen alarm; probably has what you
 need.  We have a similar situation using plumbed in CO2.  As far as regula
tory backup to justify this very minor expense, OSHA's General Duty Clause 
29 CFR 654, 5(a)1 likely covers that - especially since you've already iden
tified the specific hazard.    

Eric Clark, MS, CCHO, CHMM 
Safety & Compliance Officer 
Los Angeles County Public Health Lab 

>>>  7/7/2010 8:44 AM >>>
We are constructing a two-story building approximately 168 ft x 32 ft x 14 
ft high on the lower floor. The building will be multi-use, with offices in
 one portion and maintenance facilities adjoining. There will be six utilit
y stations in the building with nitrogen piped to each utility station alon
g with other utilities. The nitrogen supply line at each utility station wi
ll be a one-inch diameter line with a ball valve, a check valve, and a glob
e valve.

Could you please alert us to any applicable codes and standards specificall
y regarding any risks associated nitrogen asphyxiation.

Thanks and best regards,

Victor H. Edwards, Ph. D., P. E.(TX)
Director of Process Safety
Aker Solutions

Tel: +1 (713) 270-2817
Mob: +1 (713) 724-0406
Fax:    +1 (713) 270-3195
e-mail: vic.edwards**At_Symbol_Here** 

Aker Solutions Americas Inc.
3600 Briarpark Drive, Houston, Texas 77042-5206

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