When sealing a mining truck cabin with the intent of pressurization, CO2 levels can increase to dangerous levels in less than an hour, putting drivers, cabin occupants and mine workers at risk of causing fatigue, which has the potential of causing collision and workplace accidents.
Common practice in mines can be to place OEM air conditioning systems into recirculation mode to minimize dust ingress but this can result in sharp CO2 rises to unsafe levels. Likewise, alternate aftermarket pressurizer systems can do very little in terms of fresh air exchange; some manufacturers require cabs be totally sealed to allow for positive pressure increase. By sealing the cabin completely and adding an occupant exhaling CO2, the CO2 build-up can quickly reach dangerous levels that has an adverse effect on the occupant.
A good comparison in everyday life of over exposure to CO2 is when you’re driving long distances with your family. Have you ever noticed on a long journey that you begin to feel tired while driving? That is because your air conditioning could be on recirculation, preventing fresh air from entering the vehicle. You don’t notice it when it’s just you in the car, but the more occupants in the vehicle, the faster CO2 level rises.
S.A.F.E.air positively pressurizes mining vehicle cabins to prevent dust particles from entering. These dust particles could contain mineral fibers like silica and asbestos naturally found in the mining process. The integrated HEPA filters in the S.A.F.E.air unit eliminate these harmful mineral fibers by way of HEPA filtration, filtering out 99.995% of 0.3 micron.
By providing a very high rate of fresh air exchange, Freudenberg S.A.F.E.air systems keep CO2 levels down to ambient/safe levels. It purges old air and replaces it with HEPA clean, fresh air for the cabin occupants.
Freudenberg S.A.F.E.air systems also protect the entire OEM air conditioning circuit from dust ingress, meaning maintenance activities like fan and evaporator change-outs are reduced to zero. This reduction in maintenance is a major return on investment for mining companies, saving vehicle downtime and additional costs to parts over the life of the vehicle while improving employee well being.
Freudenberg Filtration Technologies did a test in a light vehicle to determine the CO2 build up in a 60 min time frame. The results were astounding – see the graph for details. For a larger image, click here.
The CO2 monitor used for this test measures in PPM (parts per million). The standard CO2 present in the earth’s atmospheres is between 250-500 PPM, noting that our test with two occupants exceeded 8000 PPM.