The Rapidox says ‘sensor heating’ but won’t begin measuring more less
What kind of gas are you running over the sensor? Does it contain hydrogen or helium? If so then the heater may be struggling to heat the sensor with such cooling gas present. Does the problem go away if room air is allowed into the analyser? Contact Cambridge Sensotec for advice. If the message continues for around eight minutes, then the analyser will give up and indicate that the internal heater has failed and the sensor needs replacing.
The Rapidox says ‘sensor cooling’ more less
It is possible to see this message briefly if the gas you are measuring changes suddenly in temperature or has hydrogen or helium present. Does the problem go away if room air is allowed into the analyser? Contact Cambridge Sensotec for advice. If the message continues for around eight minutes, then the analyser will give up and indicate that the internal heater has failed and the sensor needs replacing.
The Rapidox is reading <0.5ppm O2 which seems impossible more less
This nearly always is caused by the presence of VOCs in the gas you are measuring. In low oxygen containing gases, the VOCs burn on the hot surface of the Rapidox sensor causing all the oxygen to be locally consumed. Although the low reading is correct in terms of an equilibrium combustion reaction, it may not be the correct indication of the true oxygen content. If you are working with VOCs or things that burn such as CH4, H2 or CO in low oxygen containing gas then the zirconia senor may be incompatible and we may need to consider swapping the analyser for an electrochemical type. Please contact Cambridge Sensotec for advice.
The Rapidox is still reading <0.5ppm O2 even after I removed all the VOCs more less
The sensor may be contaminated by carbon deposits. Try running the Rapidox in fresh air over a weekend continuously so that the air can clean the hot sensor. This is often very successful! Also replace any filters in line on your system because these can also saturate with organics that will please havoc with the readings.
Why is the oxygen display flashing? more less
If you are measuring outside the normal range of the instrument you will see that the display starts to flash to indicate that it has bottomed or topped out. If this problem persists then there may be other alternative models in our range that are more suitable for you.
The pump isn’t working more less
Please check that on 1100ZF models the rear panel pump switch is on. This is not present on 1100ZR versions. Please go to the pump menu and check that the pump speed is set to a value and not set to “off”
The oxygen sensor readings seem affected by the pressure more less
Please check that the pressure correction option is set to “Auto” in the pressure menu. With this option switched off the sensor readings are greatly affected by variations in line pressure for the simple reason that the zirconia sensor is a partial pressure sensor. It is not advisable to run the machine with excessive pressure or vacuum on the inlet, although the auto correction will try to account for this up to a point.
I can’t understand the readings taken from the analogue output terminals more less
The signals that are sent to the rear terminals are fully configurable so it is important to check and know what they are set to so you can make sense of the readings. As the zirconia sensor is logarithmic in nature it often makes sense to have a logarithmic analogue output scale as well but this may not always be the case and some people prefer the raw signal to be output as well. Note that the scale for 0-10V and 4-20mA are locked together so changing one changes the other at the same time.
Can I measure oxygen in SF6 with this equipment? more less
NO – from our own experiments we know that SF6 damages zirconia sensors very quickly as the SF6 decomposes into harmful elements at the temperature of the sensor. Please do not put SF6 through your Rapidox 1100!
Is this equipment suitable for ATEX environments? more less
NO – the Rapidox is not ATEX approved and must not be used in hazardous areas. It is certified for sale area use only. DO NOT use the Rapidox to measure gases that are flammable (e.g. mixtures of methane and air) as there is a risk of an explosion occurring.
When I calibrate, the Rapidox gives strange readings that are way off the expected values. more less
Check to make sure which calibration gases are selected. Are they the same as the actual gases you used to perform the calibration? If not, you must recalibrate the analyser or reload the factory defaults to get you going again. Go to the System Info menu (13) and write down the calibration values displayed. E-mail these to Cambridge Sensotec support for advice.
When I calibrate I see the message “PRESSURE ???” more less
The message is warning you that the pressure of the cal gas is too low (<-25mbar) or too high (>25mbar) to perform a reliable calibration. Adjust your flow or pressure valve to get the pressure down as close to zero as possible. You can override the warning as it is only an advisory.
When I calibrate I see the message “GAS ???” more less
The message is warning you that the Rapidox is not getting the expected signal form the sensor that would expect from the gas you have told it you are applying. Please stop and check that the cal gas value on the cylinder matches exactly what you have entered. You can override the warning if you are sure everything is in order as it is only an advisory.
What does this R-Squared value mean? more less
New to this analyser family is a live R-squared value displayed when you are calibrating. It gives you an indication of the quality of the calibration by measuring how straight the calibration curve is. If R-squared is 1.000 then you have a perfect straight line and a perfect calibration. Anything below 1.000 is less than perfect but may still be allowable. For spec reasons we only allow calibrations with an R-squared value >0.998 to pass when new in the factory.
The sensor does not read 20.9–21.0% in air (actual value is 20.95%). more less
If the room air is very humid, it will slightly affect the observed measurement or the sensor may have drifted slightly because of natural ageing. If you are using air as a calibration point, then simply do a quick recalibration in the air to compensate for this.
I messed up the calibration procedure and now the analyser is not working properly more less
Return the box to the factory defaults using the keypad. Now try recalibrating the Rapidox.
How do I get back to the factory calibration for my instrument? more less
Follow the instructions in section 3.11 in the instructions manual.
The Rapidox won’t power up at all more less
Please check the two fuses that are in the power socket housing on the rear. Have these blown? If so replace with new ones using T2A H250V 5 x 20mm glass types making sure the spec is the same.
I replaced the fuses but the Rapidox still won’t power up more less
Is the power switch on the front panel illuminated? If it is then electricity is getting to the power supply but if the display is blank and there are no signs of life then it is most likely that the power supply has failed. Please contact Cambridge Sensotec about getting it replaced.
How often do I need to calibrate the analyser? more less
As a bare minimum the Rapidox should be recalibrated every twelve months and this is normally all that is needed for most people. If you are working in a more intense application or using the analyser continuously then a six-month calibration may be recommended. Cambridge Sensotec has approved recalibration specialists around the World – please contact us for advice.
How often do I need to change the sensor? more less
Depending on use and conditions the Rapidox sensor should last at least two years, and will not degrade during unused storage. To tell the age of your sensor go to System Info menu (13) and scroll through the information until you see a screen that displays “Run Time” in hours. This is re-set every time your sensor is changed. When the sensor gets old the heater will normally start to fail and you may only see “sensor heating” on the screen. Running the software diagnostics (see Rapidox software manual) can help us determine what is wrong with the sensor.
My application does not allow us to use electric sample pumps more less
We have an ejector option for customers who want to use compressed air to create a vacuum instead of an electric pump. Please contact Cambridge Sensotec for details.
I bought a Rapidox but want to panel mount it more less
We have a panel mount version of the Rapidox 1100 available to order or if you have already got an existing unit it may be possible to supply an upgrade kit to add a panel adapter plate. Please contact Cambridge Sensotec for more information.