Compare Oxygen Deficiency Monitors

Compare Oxygen Deficiency Monitors

Like most things in life, not all oxygen deficiency monitors are the same. There are significant differences in automobiles, lawn mowers, cell phones, as well as oxygen deficiency monitors. A number of oxygen moni­tors use what’s referred to as “fuel cell” oxygen sensors. Fuel cell oxygen sensors typically require replace­ment every 10-14 months. But that’s only half of the problem. The issue is that as fuel cell sensors age, their respective electrical outputs diminish over time (similar to a flashlight battery). This reduction in out­put mimics a low oxygen signal to the electronics. If the drop in output is significant enough, it will result in a false low oxygen alarm. Typically, with the first few false low oxygen alarms, the reaction by personnel is to treat them as actual low oxygen alarms and clear the areas in question. As these false low oxygen alarms increase in frequency, it often leads to frustration on the part of personnel, and may create a po­tentially dangerous scenario. Employees begin cancelling the audible alarms assuming they are false, when in fact they may be real low oxygen events. Cases have been documented where employees have gone as far as to permanently disable the monitor’s audible alarms due to the “nuisance factor”. Is it worth taking the risk with fuel cell oxygen sensors?

Frequent exaggerations are being made on the part of certain suppliers of zirconium oxide based oxygen deficiency monitors. Claims that the zirconium oxide sensors are calibration free for 10 years plus! One should ask why aren’t these same manufacturers offering a 10 year sensor warranty? Ironically, one of the major Japanese suppliers of the actual zirconium oxide sensor used in many of these monitors makes no such spurious claims. Upon closer examination, customers find a much different story is told when they read the instruction manual for many of these zirconium oxide oxygen monitors. One manual states, “as the oxygen sensor ages over time, it may require adjustment to 20.9%. The 02 monitor also requires pe­riodic testing with nitrogen to verify the cells response to 0% oxygen”. The manual goes on to detail how to make the adjustments (AKA calibration) to the monitor. As the old adage says, “if it sounds too good to be true, it probably is”. Trained safety personnel both understand and agree that gas monitors used to help protect personnel require occasional checks. The stakes are significant.

General Comparison Chart for Oxygen Deficiency Monitors

CAPABILITIES

Series 1300 02 Deficiency Monitor
Fuel Cell Oxygen Monitors
High Temperature (450 °C) Zirconium Oxide Oxygen Monitors

Three-year warranty on both the electronics and sensor

YES

NO – Typically one year

NO – Typically two years

Accepts up to 3 oxygen sensors with one set of electronics drastically reducing the per point monitoring costs

YES

NO

NO

Built-In data logger standard

YES

NO

Limited Availability

Easy field replacement of the oxygen sensor

YES

YES

NO – Both sensor and mating electronics need replacement – an expensive repair

Built in alarm relay contacts

YES (4 Standard)

Some at extra charge

Often an extra charge

Can be affected by changes in ambient air now caused by HVAC / air handling systems

NO

NO

YES – Changes in airflow may sufficiently cool the high temperature sensor producing erroneous oxygen readings.

Can be used in the presence of combustible gases, refrigerant gases, other reducing gases

YES

YES

NO

Long-life oxygen sensor

YES

NO

Can fail prematurely from heat fatigue

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Alpha Omega Instruments
4140 World Houston Pkwy, Suite 180
Houston, TX 77032 USA