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Confined Space Entry: Why Ventilate?
There are many good reasons to ventilate, but environmental
stability tops the list.
May 1, 2000EHS Today Staff
In the early 1900s, there was a belief that workers should not
rely on government to improve theirfate or fortune on the job;
hence, a great fight for pro-labor legislation was on. Reform came
throughthe groans and agony of those coming up out of the mines and
factories and out of every homewhere a loved one was lost. Today,
the end result of that reform lies in every OSHA regulation
andevery individual who may enter a potentially hazardous
environment such as a confined space. Letus not forget that
employee safety is the primary responsibility of all safety and
health professionals,employers and site managers.
It is disturbing that the question I am most frequently asked
is, "Why should I ventilate a particularconfined space?" We have to
wonder where the confusion lies. Is it in the interpretation of 29
CFR1910.146, in identifying the hazard in the confined space or in
something else?
In a random sampling of responses, we see a lot of similar
answers to the question, "Whyventilate?":
Replace the bad air, Make the air breathable, Get rid of toxic
vapors, Make the area warmer or cooler, Remove dust, and so on.
While all these answers are desirable results of ventilation, is
it truly the purpose of ventilation? If,under any given number of
circumstances, the above desired results could not be achieved,
wewere ventilating for the wrong reason, and frustration and
disappointment would result.
In keeping with the "safety and health of all workers," OSHA
scheduled four hearings nationwideduring 1990 and invited a vast
number of professionals to provide testimony before the
regulationsfor confined space entry were completed.
David Angelico, president of Air Systems, was one of
approximately 25 invited to Chicago to testify.A panel member asked
that very same question, "Why ventilate?" Angelico's response:
"Ventilationof a confined space should be done to stabilize the
environment. This provides us a reference pointfor the most
important piece of confined space equipment -- the atmospheric
monitor. This'stabilization' of the confined space atmosphere
minimizes the speed at which the atmosphere canor will change and
maximizes the reaction time by the worker to evaluate the change
and decide ifthey need to exit the confined space."
This basic understanding significantly reduces worker risk,
identifies the hazards of confined space
entry and puts to rest the question, "Should I ventilate?"
Understanding this concept also addressesthe need for respiratory
protection. Ventilation of a confined space area does not preclude
the use ofrespiratory protection. While ventilation may make the
atmosphere stable for work, it does notnecessarily make it
breathable. The work being performed could easily cause the
atmosphere tochange and would dictate the use of respiratory
protection.
How to Ventilate
Another frequent concern is how to ventilate the confined space.
We gain insight into the "preferred"method of ventilation by
referring to the 1910.146 standard, which states that mechanical
ventilationcontrols (a blower) should be placed in an area so that
it shall not add to the contamination of theenvironment being
ventilated. Essentially, push fresh, clean air into the area and
purge thecontaminated air in a procedure known as
"positive-pressure ventilation."
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Knowing how to calculate purge times is essential before
entering any confined space. The methodused to calculate purge
times is based upon knowing the cubic footage of the confined space
(lengthx width x height), which is divided by the cfm displacement
of the blower. The answer will designate
the length of time the blower must run to achieve a single air
exchange. A cautionary note: Nothingshould be done until complete
and accurate atmosphere evaluation is performed with
appropriateinstrumentation by qualified personnel.
Specific industries and circumstances may require inerting the
area before ventilation takes place toreduce the risk of
combustion, which could result in an explosion. This procedure
should bediscussed with a qualified safety professional.
Negative-pressure ventilation possesses its own set of specific
issues that need to be addressed.Technical assistance is of
paramount importance in the product selection process. The
productmanufacturer should be consulted as to the performance of
the product when used for negative-pressure ventilation in a
particular application. Negative-pressure ventilation brings about
differentmethods of calculation.
Most product performance issues are due to misapplication of the
product. Consumers should availthemselves of every opportunity for
manufacturers' technical assistance with regard to
ventilationproduct issues. This assistance, in most cases, will
avoid consumer dissatisfaction with productperformance.
The best ventilation product made is the product the worker will
actually use. Simple installation,ease of operation and durability
are important features to consider when evaluating
competitiveproducts. Performance, selection, innovation and
knowledge are key issues in ventilation equipment.Price, while
important, is not the only issue. My heart surgeon was not the low
bidder and, yes, yourlife or that of your fellow employee could
depend on the confined space equipment you select.
Summing Up
We have covered the basics.
Who should ventilate? Everyone. What should be ventilated?
Confined spaces. When should you ventilate? Always. Where should
you ventilate? Wherever you have a confined space. How should you
ventilate? Consult safety, industrial hygiene or authorized
personnel. Why should you ventilate? Stabilize the environment.
Remember, the best confined space is the one you do not have to
enter. If you have to enter, treat itas if your life depends on it,
because it could. Don't be safe because of legislation; be safe in
spite ofit!
Ray Ellis is vice president of sales and marketing for Air
Systems International Inc., Chesapeake,
Va. Ellis can be reached at (800) 866-8100.
