The value of 4 Gas Monitor that we carry on our apparatus, like most tools, is directly related to the proficiency of the person operating it. This week we will be developing a deeper understanding of the capabilities of the MSA Altair 5X 4 gas monitor that we use and equally important understanding what its limitations are.
The start up on the Altair 5X provides information about the devices settings and ensures that the all components are functioning properly. Below we will be reviewing each of the start up screens and and develop an understanding of the information of the information they provide.
Start Up Screen
When the pump test screen comes up, pump must be blocked to ensure that the pump is functioning properly. Hold your finger over the pump until the pump test pass screen appears.
The monitor measures the concentration of 4 separate gas types. It is important to understand how each of these measurements relate to the safety of the atmosphere in which we are working.
Combustable Gas is measured in percentage of LEL (lower explosive limit) it is important to remember this number does NOT represent the percentage of combustable gas in the ambient air but rather the percentage of the lower explosive limit of the combustable gas.
The percent of oxygen measures the total percent of Oxygen in the ambient air.
Carbon monoxide and Hydrogen Sulfide are both measured in parts per million
During the startup process the monitor displays the low alarm settings
*** It is important to remember that the normal percentage of oxygen in the ambient air is 20.8%. If the percentage of O2 begins to drop, it means that the oxygen is being displace by another unknown gas.
As well as the high alarm settings
If the gas concentrations meet of exceeds the alarm set point the device will:
-Alarm message displays and flashes in combination with the corresponding gas concentration
-Back light turns on
-Alarm Sounds
-LED lights flash red
***If combustable gas exposure exceeds 100% of LEL the monitor enters a lock alarm and XXX will be displayed in the combustable gas category
STEL (short term exposure limits) setting-displays the average exposure over a 15 minute period
Example: If you are exposed to 35 ppm for 10 minutes and 5ppm for 5 minutes your short term exposure would equal
25 ppm
TWA (Time Weighted Average) The average exposure to a substance over an 8 hour period. Generally speaking this function will be reserved for occupations that work in hazardous environments for long periods of time.
The Fresh air set up screen provides the monitor with a baseline from which to compare the potentially hazardous environment which we have been called to monitor. If you are not in a truly fresh air environment hit NO. Hitting NO will revert the the monitor to it's previous fresh air set up and thus provide a true baseline.
The sensors in the monitor are sensitive to changes in pressure, temperature, and humidity. Going from a cold dry exterior environment to a warm and humid interior environment may effect the accuracy of the monitor readings. Give the device time to adjust to the new environment before taking readings. In addition, when monitoring an area move slowly. It takes time for the air sample to move through the pump and reach the sensors. If you are moving too quickly and the monitor alarms, you may be well past the problem area Finally, remember the monitor is designed to warn us of a hazard before it becomes life threatening. If the device alarms always error on the side of caution. We carry a supply of air with us everywhere we go. Use it.
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