Info Centre >> Analex PQ Instruments FAQ >> ANALEXpqA Frequently Asked Questions and Troubleshooting Tips
These have been collated as the result of real customer experiences discussed with our product support section.
1) I use a sample rotation wheel to ensure the sample bottles are continually agitated before testing. Is the position critical?
The position of the wheel greatly effects results. If the rotating wheel is placed at a 30 degree angle you will see particles falling out on the side of the bottle. When the bottle is then tested on the PQ analyser the readings will be low at the particles are stuck to the side of the bottle.
Picture shows the rotation wheel incorrectly aligned at a 30 degree angle.
Solution: Change the angle of the wheel to 90 degrees.
2) The sample is not directly over the PQ sensor head when the measurement is taken. Is this a problem?
Alignment of the carousel in respect to the PQ sensor head is critical. If out of alignment, readings can be distorted. Also Standards could read differently. If you have the sample rotation wheel set to 30 degrees as in FAQ 1), and the side of the bottle the particles have settled to, is outside the detection zone than results will be further skewed.
Solution: Verify alignment and correct if needed. There is an alignment tool available to verify position. This is easily done by placing the alignment ring on the carousel when it is in the home position (after power up). If you can see the sensor is out of line by more than +/- 2mm then the instrument is out of alignment.
3) I am getting erratic readings with sample bottles often reading too high, but when I use the standard or test samples I get consistent readings.
The PQ sensor head is a very high sensitivity device and the readings can change significantly and read high (by up to 200PQ) if there is any weight pressing on it, even the weight of a sample pot or sample bottle. It will act like a weigh scale.
If the sample bottle cap or PQ pot is bowed out on the bottom, the centre can be pressing on the sensor head. When the 750 PQ standard is used or the standard pots they are flat so do not press on the sensor head.
Solution: Replace bowed bottle caps with flat ones or use a new sample pot.
4) I am getting erratic readings with sample bottles often reading too high.
The PQ sensor head is a very high sensitivity device and the readings can change significantly and read high (by up to 200PQ) if there is any weight pressing on it, even the weight of a sample pot or sample bottle. It will act like a weigh scale.
Position of the detector height in relation to the instrument shell is critical. With an improperly positioned detector the pressure from the weight of the oil sample will skew the results high. The detector should be just below the instrument case by 0.2 to0.5mm. As the machine is used the top surface of the case can be worn causing the sensor to become incorrectly positioned.
Solution: Lower the detector and place a plastic shim in place. Make sure the detector is just below the case by 0.2 to 0.5mm.
5) Does it matter how much sample is in the sample pots or the bottle?
The sample pot should always be full to the brim, if there is less sample the reading will be lower. Similarly the amount of oil in the Bottle can affect the result. A bottle with just a few millimeters will read differently than a full bottle.
Solution: Ensure that the bottle has at least 40mm depth of oil in it. Lower volume of oil can be measured but the reading may be low as a result.
6) Why is the location of the instrument critical?
The PQ sensor head is designed to measure microscopic changes in the magnetic field above it. This is how it can detect such small amounts of ferrous debris. Because of its sensitivity it can also pick up magnetic field generated by such things as loudspeaker, CRT monitors, PC’s, cell phones, electric motors in other lab equipment, electrical cables, even the workbench if it has a metal top.
Solution: Locate the instrument away from sources of magnetic fields; consider the use of wooden shelves and cabinets. Use LCD screens instead of CRT monitors, banning the use of cell phones in proximity of the instrument, and relocating rotators etc.
7) My 750 standard does not drop easily into the measurement carousel and when I calibrate one day I get different results to the previous day.
The 750 standard is designed to be a close fit into the measurement carousel but it must be loose enough to float as the measurement carousel rotates. We have found that if the standard wears or gets contaminated with dirt is can start to bind in the measurement carousel causing incorrect calibration.
Solution: Make sure your 750 standard not only rotates freely and easily in the carousel and also drops in cleanly. If it does not, try cleaning the outside edge of the standard and the hole in the carousel. If you still have a problem it is recommended to have it recalibrated and replaced by Kittiwake. We check each standard as part of the calibration procedure.
8) My PQA Measurement carousel is not rotating, the motor is going and the measurement carousel is free to move by hand.
The PQA carousel is driven by a motor via a belt. Sometimes this belt can become stretched or contaminated with oil and it can even come off the pulleys.
Solution: Follow the belt cleaning and adjustment procedure. If this does not work then Kittiwake can supply a replacement belt
9) My PQA Measurement carousel is not rotating, it seems to be very stiff as if it is catching or binding.
The Measurement Carousel is a close fit to the white Sample Carousel fixed platter. This to ensure a smooth movement of the sample pots when the carousel rotates. Dirt and grit can collect in the gap between the Measurement Carousel and the fixed platter. This causes the measurement carousel to bind and even jam. You can confirm this is the problem by removing the drive belt and checking the Measurement Carousel rotates freely, if there is any jamming or stiffness it will be obvious.
Solution: Remove the measurement platter and clean the out edge of the measurement carousel and the inner edge of the white platter. When complete you should be able to fit a piece of paper in the gap all the way round.
10) My 144 sample carousel sometimes jams for no reason.
The smooth operation of this relies on the Measurement platter being lelve with the white platter. If there is a step between the two surfaces pots can become stuck on this edge.
Solution: The white platter can be adjusted in height using non ferrous washers and shims by loosening the large screws.
11) I do not have a suitable adaptor for the bottle I am using; will I get valid readings without an adaptor?
Do not attempt to use the instrument without the bottle adaptor. This is because the bottle must be central over the sensor when taking a measurement. Without an adaptor the bottle will only be partially over the sensor and hence a low reading will be given
Solution: Kittiwake has a number of different adaptors available from stock. If it is an unusual size we can have a special one made.
12) Can I manually change samples on the PQA whilst the turntable is moving?
The measurement carousel resets when you power the unit up so the instrument knows where the sample is at any one time. If you put a sample on manually whilst it is moving this can case the turntable to get out of synchronization from its rest position. This will mean a reading is taken when the reference standards and the samples are not positioned over the sensor. You will get large positive and negative readings and meaningless results.
Solution: Never put a sample on the turntable whilst it is moving. If you inadvertently cause a jam on the turntable reset the position by turning the power on and off. If you need to operate using this method (as one of our customers did) we have an upgrade of the software available that pauses the motion of the Measurement Carousel to allow a sample to be put on.
13) Are there any restrictions as to the type of labels that can be used on the sample bottle?
Some labels have a metal content which causes errors in the readings. These types of labels should not be used. Also note that Laser printers work by depositing carbon on the paper. This carbon can also detected by the instrument causing higher reading than normal.
Solution: Make sure you are using non metallic labels and if you need to print details on the label use inkjet or thermal transfers resin based printers NEVER laser printers.
14) Do the oil samples have to be cool before I measure them?
The samples should be allow to stabilize at the same room temperature as the instrument before using and should never be put on warm. The sensor head is manufactured from coils using copper wire. This copper wire has a resistance that changes as the temperature changes. The sensor coil has two such windings; one which is a reference coil located inside the instrument, and another is the measurement coil located us under the sample. When the instrument has been on some time the temperatures of these two coils are the same. This has the effect of canceling out any changes in the room temperature. If you introduce a warm sample to the sensor, the measurement coil is warmed and the unbalances the sensor causing incorrect readings.
Solution: The samples (and the 750 standard) should be allow to stabilize at the same room temperature as the instrument before using and should never be put on warm.