More often than not, if you have ever used a gas monitor, you have used one in a confined space area. Confined spaces are described by OSHA as a work area that is not designed to have people in it but is big enough to get down into and do your work. A confined space typically has a very restricted accessibility point which is not meant for continuous occupancy. The most common confined space we think of is underneath a manhole cover of sorts. There are a lot of areas that are a confined space that you may not think of, such as the following: vessels, tanks, silos, storage bins, vaults, hoppers, tunnels, equipment housing, pipelines, ductwork, pits, etc.
Approximately 60% of all deaths in a confined space are would be rescue workers. A worker goes down and is incapacitated by the gas and the hole watch runs down to check on him and in turn is exposed to the gas as well. The best way to erase this catastrophic accident is to use proper gas detection equipment and gas detection procedures.
Everyone that has any amount of experience in this work environment knows you must test the atmosphere before entering a confined space. Seems easy enough, right? Sure, but it also is a little more complex. If you were to go hunting and showed up and unpacked your gear, set your spot up and immediately saw no deer, would you leave and make an assumption that there were no deer? Or would you be patient to make sure there were no deer? The same is to be said for testing confined spaces. Hunting takes an investment of time, patience and expertise. You can’t drop a line in a manhole and if there are no alarms just instantly raise the hose and proceed to go into the confined space.
The proper way to measure the gasses in a confined space are by what is referred to as the 2×2 method. This method’s procedures state to have 2 minutes of sampling time PLUS an additional two minutes for each foot of hose that is used for the testing. A relatable situation would be this. If the worker is measuring a 15-foot space that is 30 feet down then the test would be 3 minutes. By using the 2×2 method we see the 2 minutes for the space and then 60 seconds additional to account for the 30 feet of tubing. It is advised to use these 3 minutes to check out other possible hazards that are close to the confined space you are working with.
The second common failure when testing confined spaces is again tied to the method. Long ago there was a time when the best option was to tie a monitor to a rope and throw it down the hole and listen for a beep. Fortunately, that is certainly not the case any longer. A person working in these spaces should not ever practice this method. The correct (and modern) way to do this testing is to use a hose and a pump to sample the environment in question. This way you can see the readings since the monitor isn’t hanging down below, and secondly you won’t have to worry about the monitor falling into the hole.
Lastly, just because your 2×2 testing method said things were good to go doesn’t mean that they will stay in that condition. The atmosphere is never static, it is constantly fluctuating at your work space. There should always be a monitor that continuously checks the environmental changes to ensure that your work space remains a safe environment. The only way to ensure this is by having a monitor running that is continuously measuring the gasses in the environment you are working in. Blower fans may seem like you are pushing ventilation and therefore this helps keep the environment safe. On the other hand, you don’t have a way of knowing if you are providing enough force to neutralize the hazards, and also the fan can be blowing dirty air (i.e. if the fan is close to an exhaust).
JM Test Systems is here to assist you with your needs to ensure that you verify and maintain a safe work environment. JM Test Systems recommends the RKI Eagle 2 for performing the initial test at your confined space and we also recommend the RKI GX-2009/RKI GX-3R to wear on your person to maintain a verification of a safe work environment.