It seems the article last week was an eye-opener for a lot of folks! The response has been overwhelming from many of you and several suggested that I take the “limitations” a step further. Seems a lot of you broke out your owners’ manuals and enjoyed some holiday reading; learning that these devices have even more limitations. This posting is merely a listing of items that are often times never followed/met when using these devices:
NOTE: These items are from a specific brand and model and are NOT intended to be inclusive or representative of all devices. YOU MUST refer to the actual owners/operations manual for the specific device(s) in use at your workplace.
- The ATEX directive is only valid until 25% Vol O2. Alternative use or use outside this specification will be considered as non-compliance.
This means that using this device in atmospheres with enriched oxygen concentrations above 25%, the device could pose as an ignition source for the flammable and oxygen enriched atmosphere.
- Before each day’s use, check the function of the device, XXXXXXXXX recommends carrying out a routine inspection prior to each day’s use. Bump test frequency is often stipulated by national or corporate regulations; however, bump testing before each day´s use is generally the accepted best safety practice and is, therefore, XXXXXXXXXX’s recommendation. The device must pass the bump test. If it fails the test, perform a calibration before using the device.
- Perform a bump test MORE FREQUENTLY if the device is subjected to PHYSICAL SHOCK OR HIGH LEVELS OF CONTAMINANTS.
- Perform a bump test MORE FREQUENTLY if the tested atmosphere contains the following materials, which may desensitize the combustible gas sensor and reduce its readings:
- Organic silicones
- Silicates
- Lead-containing compounds
- Hydrogen sulphide exposures over 200 ppm or exposures over 50 ppm for one minute.
- A combustible gas reading of “XXX” indicates the atmosphere is above 100% LEL and an explosion hazard exists.
- Do NOT use the device to test for combustible or toxic gases in the following atmospheres as this may result in erroneous readings:
- Oxygen-deficient or oxygen-rich atmospheres
- Reducing Atmospheres
- Furnace stacks
- Inert environments
- Atmospheres containing combustible airborne mists/dusts
- Use the device ONLY to detect gases/vapours for which a sensor is installed.
- Make sure adequate oxygen is present for accurate combustible readings with the catalytic sensor (>10% O2).
- NOT to be used for gases having a flashpoint in excess of 38°C (100°F). Do NOT use the device to test for combustible gases in atmospheres containing vapors from liquids with a high flash point [above 38°C/100°F], as this may result in erroneously low readings.
- Recheck calibration if the device is subjected to PHYSICAL SHOCK.
- Do NOT use compressed air to clean the sensor holes, as the pressure may damage the sensors.
- Allow sufficient time for the device to display accurate reading. Response times vary based on the type of sensor being utilized. A number of environmental factors may affect the sensor readings, including changes in pressure, humidity and temperature. Pressure and humidity changes also affect the amount of oxygen actually present in the atmosphere.
- The nominal run-time of the device at room temperature is 24 hours. Actual runtime will vary depending on ambient temperature and alarm conditions. The runtime of the device at -20°C (-4°F) will be approximately 14 hours. The charger is capable of charging a completely depleted pack in less than four (4) hours in normal, room-temperature environments.
- Minimum and maximum ambient temperature to charge the device is 10°C (50°F) and 35°C (95°F), respectively. For best results, charge the device at room temperature [74°F].
- It is recommended that an oxygen calibration be performed at the TEMPERATURE AND PRESSURE OF USE. Be sure that the device is in known fresh air before performing a calibration.
- A number of environmental factors may affect the gas sensor readings, including CHANGES IN PRESSURE, HUMIDITY AND TEMPERATURE.
Pressure and humidity changes affect the amount of oxygen actually present in the atmosphere.
- If PRESSURE CHANGES RAPIDLY [e.g., stepping through airlock], the oxygen sensor reading may temporarily shift and possibly cause the detector to alarm. While the percentage of oxygen may remain at or near 20.8 Vol %, the total amount of oxygen present in the atmosphere available for respiration may become a hazard if the overall pressure is reduced by a significant degree.
- If HUMIDITY CHANGES BY ANY SIGNIFICANT DEGREE [e.g., going from a dry, air conditioned environment to outdoor, moisture laden air], oxygen readings can be reduced by up to 0.5 %, due to water vapor in the air displacing oxygen. The oxygen sensor has a special filter to reduce the effects of humidity changes on oxygen readings. This effect will not be noticed immediately, but slowly impacts oxygen readings over several hours.
- When gas reading exceeds 100% LEL, the device enters a Lock Alarm state , the combustible sensor shuts down and displays “xxx” in place of the actual reading. This state can only be reset by turning the device off and on in a fresh air environment.
Attention! A combustible gas reading of “100” indicates the atmosphere is above 100% LEL CH4 and an explosion hazard exists. Move away from the contaminated area immediately.
- If TEMPERATURE SHIFTS DRAMATICALLY, the sensor reading may shift. Zero the device at the work site temperature for the least effect.
- Do NOT activate the Fresh Air Setup unless you are CERTAIN you are in fresh, uncontaminated air; otherwise, inaccurate readings can occur which can falsely indicate that a hazardous atmosphere is safe. If you have any doubts as to the quality of the surrounding air, do NOT use the Fresh Air Setup feature.
- Do NOT use the Fresh Air Setup as a substitute for daily calibration checks. The calibration check is required to verify span accuracy. Failure to follow this warning can result in serious personal injury or death.
- If a battery charging cycle is INTERRUPTED before it is completed [4 hours for a fully discharged battery], allow the device’s internal temperature to stabilize for 30 minutes before performing a Fresh Air Setup.
- Perform a FULL CALIBRATION periodically to ensure accuracy and immediately if the device fails the Bump Test. ATTENTION! Perform a Bump Test to verify proper device operation. Failure to perform this test can result in serious personal injury or death. Bump test frequency is often stipulated by national or corporate regulations; however, bump testing before each day’s use is generally the accepted best safety practice and is therefore XXXXXXXXXX’s recommendation.
- Calibration is REQUIRED after a sensor is installed; otherwise, the device will not perform as expected and persons relying on this product for their safety could sustain serious personal injury or death.
- Allow sensors to stabilize at room temperature for at least 30 MINUTES BEFORE CALIBRATION.
- Clean the exterior of the device regularly using only a damp cloth. Do NOT use cleaning agents as many contain silicones which will damage the combustible sensor.
- When not in use, store the device in a safe, dry place between 18°C and 30°C (65°F and 86°F). After storage, always recheck device calibration BEFORE use.
- Combustible Gas response time 90% of final reading in less than or equal to 15 sec (pentane) and 10 sec (methane) (normal temperature range).
- The oxygen sensor has built-in temperature compensation. However, if temperature shifts dramatically, the oxygen sensor reading may shift. Zero the device at a temperature within 30°C of the workplace temperature for the least effect.
- Oxygen sensor response time (90% of final reading) <10 seconds (normal temperature range)
- The model XXXXXXXX shall ONLY be charged and opened in a non-hazardous area.
- The model XXXXXXXXXX shall NOT be used in Zone 0 when the combustible XCell Ex sensor is installed.
- Zone 0 classified is an area where ignitable concentrations of flammable gases, vapors or liquids are present continuously or for long periods of time under normal operating conditions. An example of this would be the vapor space above the liquid in the top of a tank or drum.
