Re[2]: [TheForge] carbon monoxide

[Wayne Ackman]

Hello 

Thanks Bruce, that's what I wanted to know.

What is a good way to vent a propane
forge?   I have a vent fan I used to use in a darkroom.
and was thinking of putting it in the wall by the
forge.

-- 
Wayne                           
Hesperus, CO


Tuesday, November 12, 2002, 6:54:07 AM, you wrote:


BF> Wayne,

BF> This is what MSDS's are for.  Anytime you have a question like this, consult an MSDS.

BF> According to an MSDS for carbon monoxide from BOC gases
BF> www.mwsc.com/MSDS/8.PDF 

BF> PEL-OSHA is 50 ppm TWA
BF> TLV-ACGIH is 25 ppm TWA
BF> LC50 is 1807 ppm/4 h (rat)

BF> Starting with the last, that's the "concentration lethal  to 50% of test rats".  If you happen to be a rat, then you can expect 1807 ppm to have a 50% chance of killing you outright in four hours.

BF> The top figure is the "Permissible Exposure Limit from the Occupational Health and Safety Administration," namely a "time-weighted average" of 50 ppm.  The time period is not stated here, but
BF> typically it's "one shift" or eight hours.  If you were exposed to 50 ppm continuously for eight hours (and then NOT exposed), OSHA wouldn't object.  (OSHA hates it when people die on the job! 
BF> It makes so much extra paperwork for them!)   TWA, however, allows you to be briefly exposed to higher levels, as long as the normal exposure is less.

BF> ACGIH is the American Conference of Governmental Industrial Hygienists, Inc., a non-governmental organization.  The following website below provides a definition of TLV:
BF> http://www.ilpi.com/msds/ref/index.html

BF>           "Threshold Limit Values (TLV's) are guidelines (not standards) prepared by the American Conference of Governmental industrial Hygienists, Inc
BF>           (ACGIH) to assist industrial hygienists in making decisions regarding safe levels of exposure to various hazards found in the workplace.

BF>          " A TLV� reflects the level of exposure that the typical worker can experience without an unreasonable risk of disease or injury. TLVs� are not
BF>           quantitative estimates of risk at different exposure levels or by different routes of exposure."

BF> I would conclude that 40-50 ppm is not enough to cause you injury, but that you wouldn't want the level to go any higher.  It would be a good idea to try to get it down to about 25 ppm.

BF> However, to REALLY know what the level is, you must first calibrate the CO detector.  Maybe it's already in calibration, maybe not.  I have no good suggestions how to do this.  In industry it
BF> would be done from a source of known CO level, such as a gas mixture.  Such a mixture is likely to be above your budget.  The best bet is to contact the manufacturer and tell them you're getting
BF> high readings (50 ppm) near a combustion source and want to make sure the detector is working properly before you worry about fixing a problem with th source.  They may have an answer for you.

BF> Hope this helps,

BF> Bruce
BF> NJ

>>>> LongHollow.Forge@starband.net 11/09/02 02:02PM >>>
BF> Hello 

BF>   I bought a CO/propane detector for my shop as I have
BF>   done all the plumbing myself and wanted to make sure
BF>   I don't have any leaks, etc.  Install has gone fine,
BF>   but now that I have a CO detector I can monitor the
BF>   amount of CO produced by my propane forge.  When it
BF>   comes up to temperature the monitor registers about
BF>   40-50 PPM. I am sure it would keep climbing but I
BF>   open a couple windows, put a fan in for exhaust
BF>   and clear it out.

BF>   My question is: do you all think the forge is tuned
BF>   properly?  Are those kind of readings appropriate?
BF>   What is a good way to vent a forge?