Ventilation is one of the central pillars of confined space safety. Fumes, vapors, and volatile organic compounds accumulate and create an atmosphere that is not conducive to breathing. And I think we can all agree that breathing is a central pillar of living.
OSHA calls ventilation one of the most important engineering controls available to maintain a safe work environment. We agree. And we've got a number of smart ways to accomplish replacing the atmosphere of your toxic environment. The question is how much ventilation is needed, and how can you best keep track of the situation.
While the actual standards for an acceptable atmosphere haven't changed over the past few years, there is disagreement over the length of time needed to ventilate a space before entry. In OSHA's confined space standard CFR 1910.146, they do not specify how many air exchanges must be circulated per hour. Some state laws require a minimum air exchange amount of 6 times per hour, but that number is by no means universal.
A common rule of thumb has always been 5 complete air exchanges. There are other experts who advocate 7 or 10 complete changes before work begins. Allegro Industries, manufacturers of ventilation products, recommend 20 air exchanges just to be on the safe side, but they suggest the best way to determine safety for your particular space is by having a professional perform a complete and accurate atmosphere evaluation with proper instrumentation to determine what their recommendation would be.
In practice, our customers typically ventilate for as long as possible before entry, and those who plan their days well often set up the equipment and get it fired up far in advance of the scheduled work. Whichever guidelines your company decides to follow, ongoing monitoring of the space using a confined space gas monitor allows entrants to make sure the atmosphere stays safe.
To calculate the time needed to purge the air while workers are in a space requires taking the loss of airflow from bends in the ducting into consideration. This nomograph, or alignment chart, is a graphical calculating device which can help you figure out what capacity blower you need.
Depending on the size of your space, you may find the Ecko K2025 Blower/Ducting/Canister Combo a good choice. This all-in-one unit stores and protects the ducting as well, and is easy to haul around your site. Another advantage of the K2025 is that it can move up to 980 cubic feet per minute (CFM) without making you deaf like some blowers. While 74dB isn't quiet by any stretch of the imagination, it's pretty darn subdued for a ventilation unit that moves this much air.
Another favorite of our customers is the Ecko K30 12 in. Blower from Euramco. The Ecko line is Euramco's economy line of blowers, and they don't come with the costly certifications of the RamFans. But they also don't come with a $2000 price tag. The K30 moves up to 2400 CFM for less than $400 and the available ducting is easy to attach on either end of the unit depending on whether you're pushing air in or pulling it out.
If you have questions about the size or capacity of the blower that's right for your application, give our Customer Service folks a call at 1-800-829-9580. They can help you breathe easy (if you'll pardon the pun).