Questions to ask prior to purchasing a gas meter
1) What gases do I need to detect? OSHA requires you to monitor for any gas that is combustible/flammable or poses a health threat. Low Oxygen levels as well as any toxic gas needs to be monitored. The most common use of gas detectors is their use to monitor confined spaces.
Common Gases & where they are found
Methane (CH4) (Combustible/LEL): Methane gas is commonly caused when organic materials get digested by microorganisms, which release methane as a by-product. Methane gas is commonly found at landfills, wetlands, sewers, agriculture, biofuels, oil refining.
Oxygen (O2): Oxygen levels are typically at 21% in the atmosphere. Oxygen can be displaced by other gases especially in confined spaces. Low Oxygen levels pose a health risk when the Oxygen drops below 19.5%.
Hydrogen Sulfide (H2S): Hydrogen sulfide is produced by bacterial breakdown of organic materials and wastes. Activities that can produce H2S gas include petroleum/natural gas drilling and refining, wastewater treatment, landfills, coke ovens, tanneries, and Kraft paper mills.
Carbon Monoxide (CO): Carbon monoxide is produced when fuels such as gas, oil, coal and wood do not burn completely (poor combustion). Carbon Monoxide is commonly caused by vehicles, boilers & furnaces, gas driven machinery, water heaters, and cookers.
Toxic gases: Although CO and H2S are commonly monitored for, OSHA requires you to monitor any gas that poses a health risk. Gas meters are available with many gas combinations. If you don’t find the combination you require, please contact out technical group for assistance.
2) What features and options do you need?
Sampling Pump: A pump allows you to pre-test a confined space prior to entry. Since some gases are lighter than air and others are heavier then air you must test the entire space for gas. Please specify the length of hose you need to enable you to test the entire space. A sample pump with hose and probe is also useful in leak detection as it enables you to test for leaks around valves and fittings.
Size-Large or small? Generally the larger the meter the more robust it is. Although larger gas meters are more expensive they are designed for heavy duty use. If you application is demanding then you should consider a lunch box style meter like the RKI Eagle or Eagle 2. Smaller meters are better for use as a personal monitor. They are less expensive and allow freedom of movement. The best option is to outfit the entrant with a small portable meter and the stand-by with a larger lunchbox style meter.
Batteries: Rechargeable or Replacement Alkaline batteries. Most meters provide 8-12 hours of operation from each new set of Alkaline batteries. Due to this most end users purchase rechargeable batteries. The downside of rechargeable batteries is that if you forget to charge the batteries the meter will not work. Many of the meters we sell can be supplied with both options so that if you forget to charge the batteries you can insert Alkaline batteries.
Data-Logging: Most meters we sell are available with data-logging. Data-logging allows the user to record daily gas readings with time and date stamps for record keeping requirements. Most meters can record over a weeks’ worth of readings.
3) What sensing technology is best for my application?
This is where our in house technical group can assist you the most. Some gases may damage a gas sensor. For example a Catalytic style combustible sensor can be damaged by Chlorine and Halogenated gases. If this is the case then an (IR) infra-red sensor may be the answer. Some gases present a toxic hazard well before a gas becomes flammable. If this is the case you need to monitor this gas in the low ppm or PPB range. A (PID) Photo-ionization detectors can detect organic vapors in the very low PPM and PPB range.
Limitations: If the environment you intend to monitor is too harsh to support life then the meter will not survive that environment. These meters are designed to detect gas in low concentrations and should never be exposed to conditions outside of their specifications. Please see the meter specifications which detail the temperature, humidity and gas range of the meter prior to purchase. If you are not sure the meter is correct for your application, please contact out technical group for assistance.
Disclaimer:There are many other hazards to consider when entering a confined space. These statements and other articles listed within this website are general outlines of some of the requirement as they relate to gases found in a confined spaces.
Smallest 4-gas meter in the world GX2009 – Size of a pager; a vibration alarm calls you attention to the meter in high noise environments, add on sample pump for remote sample capability, 2 year warranty. Great for climbing ladders and entering tight spaces.
Best Bang for the buck QRAE III – Packed with features: internal sample pump, vibration, audible, visual alarm, rechargeable battery pack can be swapped with alkaline battery pack, large LCD display, data-logging, TWA/STEL alarms, min. max readings.
Rough and Tough Eagle 1 & Eagle 2 – For heavy duty use. Takes abuse that smaller portable meters can’t survive in. To many features to list – Please see specifications for details.
Broad Range Sensitivity MultiRAE – Detects VOC’s in the ppm gas range. When a gas is toxic, before it becomes flammable, this is the meter for the job. This meter detect a broad range of gases. Please contact out technical group for assistance in picking the correct MultiRae meter for you application.