A combustion analyzer is an expensive precision instrument that needs a certain level of preventive maintenance to remain in good condition and give reliable results. Most combustion analyzers use electrochemical sensors to measure gas concentrations, and these require calibration at least once a year. Here is a section on calibration procedure. The most common problems with the combustion analyzer are condensation in the gas flow system and dirty filters. Condensation is always a topic with combustion analyzers. There are large models with internal sample conditioners where this is no longer a difficulty, but most of the smaller combustion analyzers simply have water traps. It is essential to empty water traps before they overflow and allow larger quantities of water into the internal tubing of the combustion analyzer. This not nice, clean water that will dry out without any problems. It contains combustion residues and dissolved acids that will cause damage and clog pumps etc. Even in normal use there will be a certain amount of condensation inside the combustion analyzer, despite the water traps. This is very difficult to avoid, even with multiple water traps some water will get through in time. The gas passing through will still be super hydrated, with water present in micro droplet form, which will deposit condensate on the internal tubing of the combustion analyzer. This is a slow process and will not be noticeable if the analyzer is only used for short periods, but will add up and will become serious if the combustion analyzer is used for longer periods. This is best avoided by allowing the analyzer to run for a few minutes after a measurement, both to allow the sensors to return to zero and to dry out the internal tubing.
This all means that a combustion analyzer must be protected from condensate as far as possible, but it will still be necessary to clean the pump and gas tubing at the annual service to remove any deposits that have formed. Filters should be inspected whenever the combustion analyzer is used. A dirty filter will reduce the gas flow rate. Some instruments will show this fact, but most will not. A blocked filter may lead to low or nonexistent gas flow. The other problem is that unfiltered gas may leak around the sides of the filter to contaminate the inside of the combustion analyzer.
Combustion analyzers are generally powered by internal rechargeable batteries with a mains charger either internally or externally. These have to be charged occasionally to keep them fresh since the combustion analyzer will generally require a small amount of current even when switched off to run the clock and perhaps provide a bias voltage for some of the sensors. If they are not charged regularly, then they will become completely empty and defective. Observe the manufacturers instructions, but once a month is usually fine.
The electrochemical sensors in a combustion analyzer will wear out even when the instrument is sitting in the office and not being used. Keeping the equipment in a cool place is a good step towards a longer life. If the combustion analyzer is not to be used for a longer period of time (over summer or similar), then it may prove worthwhile to disconnect the oxygen sensor for this time. It must be reconnected in good time since it will take a few hours to stabilize again after this.
A combustion analyzer will generally get at least dirty in use, so it will require cleaning. Obviously, electronic equipment does not work well if you allow water inside it, so care should be used. Do not use chemical solvents to clean combustion analyzers, since the fumes may react with the electrochemical sensors to produce strange reactions. This may even lead to permanent damage and unscheduled service date for the combustion analyzer.
A combustion analyzer is designed generally for use in an industrial environment, but it is a measuring instrument and should be treated with a certain amount of care. It will then give years of accurate measurements if all calibration and general service necessities are seen to.