Confined Space Entry: Why Ventilate?

There are many good reasons to ventilate, but environmental stability tops the list.

In the early 1900s, there was a belief that workers should not rely on government to improve their fate or fortune on the job; hence, a great fight for pro-labor legislation was on. Reform came through the groans and agony of those coming up out of the mines and factories and out of every home where a loved one was lost. Today, the end result of that reform lies in every OSHA regulation and every individual who may enter a potentially hazardous environment such as a confined space. Let us 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 particular confined space?" We have to wonder where the confusion lies. Is it in the interpretation of 29 CFR 1910.146, 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, "Why ventilate?":

  • 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, we were 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 nationwide during 1990 and invited a vast number of professionals to provide testimony before the regulations for 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: "Ventilation of a confined space should be done to stabilize the environment. This provides us a reference point for 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 can or will change and maximizes the reaction time by the worker to evaluate the change and decide if they 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 addresses the need for respiratory protection. Ventilation of a confined space area does not preclude the use of respiratory protection. While ventilation may make the atmosphere stable for work, it does not necessarily make it breathable. The work being performed could easily cause the atmosphere to change 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 ventilation controls (a blower) should be placed in an area so that it shall not add to the contamination of the environment being ventilated. Essentially, push fresh, clean air into the area and purge the contaminated air in a procedure known as "positive-pressure ventilation."

Knowing how to calculate purge times is essential before entering any confined space. The method used to calculate purge times is based upon knowing the cubic footage of the confined space (length x 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: Nothing should be done until complete and accurate atmosphere evaluation is performed with appropriate instrumentation by qualified personnel.

Specific industries and circumstances may require inerting the area before ventilation takes place to reduce the risk of combustion, which could result in an explosion. This procedure should be discussed 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 product manufacturer 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 different methods of calculation.

Most product performance issues are due to misapplication of the product. Consumers should avail themselves of every opportunity for manufacturers' technical assistance with regard to ventilation product issues. This assistance, in most cases, will avoid consumer dissatisfaction with product performance.

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 competitive products. 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, your life 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 it as if your life depends on it, because it could. Don't be safe because of legislation; be safe in spite of it!

Ray Ellis is vice president of sales and marketing for Air Systems International Inc., Chesapeake, Va. Ellis can be reached at (800) 866-8100.

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