Corossion Acid and IAQ Problems in a Miami Lab.
CASE STUDY 1-27-12
This is text from an actual IAQ or indoor air quality problem investigation conducted by us at a marine bioloy lab in Miami Fl.
Excessive corrosion observed on many metal items including but not limited to:
drill bit like device
metal tissue dispenser
previous light fixtures
Aluminum frame on frig door
And rust was a serious problem on dozens of other metal objects large and small throughout the entire
marine biology reseace lab.
WHAT DID NOT CAUSE THE PROBLEM
An exhaustive list of several hundred chemicals stored at the property were provided to the inspector
Hundreds of chemicals were present in the lab in cabinets and refrigerators etc.
Despite being present they posed little true threat, they are small amounts of chemicals in small closed glass containers, few are used on occasion, and the vast majority are never used or opened based on interview information gleamed from lab workers.
Chemicals in glass jars do not typically cause problems in surrounding air at this point it is only logical to rule out these tiny closed jars of mostly non reactive agents.
WHAT DID CAUSE THE PROBLEM
1) Three containers of hydrochloric acid (HCL) are present about 25 gallons total. This is a massive amount of chemicals and may be more than all the other chemicals combined in the lab. Thus this acid is a possible source of IAQ problems.
2) Hydrochloric acid and it's fumes are extremely reactive and corrosive to almost any metal it is exposed to. According the metal expert Ted Mooney P.E. "Hydrochloric acid attacks metal and will dissolve it . . . but it dissolves rust even faster than it dissolves metal. So it is used in industry to de-rust metal before painting or plating. But after acid dipping the metal is very prone to flash rusting, and if metal is subject to hydrochloric acid fumes it will rust terribly. source: Ted mooney at www.finishing.com.
3) The containers were not at all closed tight, only very loose lids were provided that did not prevent the escape of fumes at all.
4) Hydrochloric acid is volatile, this means it will evaporate at room temperature and room pressure.
5) The acid is used almost on a daily basis to wash test tubes, this from lab personnel interviews.
6) We know acid was in the air because the inspector could smell it when it was in use.
This acid was a very serious concern and undoubtedly the source of corrosion.
HOW THE PROBLEM WAS DISCOVERED
Cabinet handles were more rusted on the end of the lab where the acid baths were.
Metal support rods on the 1/2 of the lab with acid were also more rusted than on the other side of the lab.
Door frames near acid baths were very corroded but door frames on the other side of the lab were not corroded at all even where paint was chipped.
Copper pipes under the tables near the acid are more green and corroded than on the opposite side of the lab.
This indicates that hydrochloric acid is likely causing your corrosion.
WHY IT IS HAPPENING IN THIS BUILDING BUT NOT IN THE PREVIOUS BUILDING LOCATION OF THIS SAME LAB
Air flow or negative pressure in this lab is very weak this can be demonstrated with a chem wipe paper towel at the door opened 1/4 inch.
At other labs doors air flow is strong, at this one air flow is very weak.
The reason your negative air flow is weak is likely at least in part because a baffle door on the roofs vent hood is rusted in the open position, so instead of getting good suction and venting lab air, you are venting a good percentage of roof air as well. replacing the baffle and closing it will likely increase your negative pressure if this is the hood for this lab. This will likely increase the removal of acid fumes out of the lab.
Humidity is not extremely high in the lab today 55%RH at 71F 63 grains of moisture, this is satisfactory.
Humidity is very high at times when it is raining outside.
This is know because the building manager reported excess condensation weeks ago during heavy rains, this occurred in this lab but was not a serious problem in this lab today.
The previous lab location was twice the cubic foot roughly, thus concentrations of acid i n the air may have been 1/2 what they are not if all else was the same.
Have test and balance reviews done by a ventilation experts, have them review the above referenced baffle, it visible from on the roof, the baffle should be CLOSED AND NOT OPENED, sounds backwards but this is likely part of the answer. closing it may force more air to be vented out of the lab.
Have a good quality strong rust resistant vent hood & duct system installed above the acid bathes and have it turned on when the acid baths are in use, or have it on anytime the acid is present.
Have the acid stored in proper and safe containers approved by the manufacturer or provider of hydrochloric acid containers. It sounds logical to keep it in tight containers, but this may or may not cause dangerous fume build up so consult with the provider of the appropriate acid containers for storage advice.
The IAQ inspector was given a general list of hundreds of chemicals so the inspector did a test for hundreds of chemicals at the parts per billion levels using thermal desorption tubes analyzed using GC/MS.
Sample results only picked up a small number of chemicals, and levels were low.
Acid was tested for by the previous IAQ company so this inspector did not test for acid.
See our lab report from Prism Analytical.