Any topics covered about anemometer calibration, air velocity wind tunnels, blockage effects, calibration techniques and ISO 17025 accreditation.
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Anemometer Calibration
Posted in Air Velocity Calibration | The post has tags: Air Velocity Calibration, anemometer calibration, bs 1042
Do anemometers need to be calibrated in the same orientation as being used. We test laminar fume cupboards and often have to use the anemometer in a horizontal plane, but I know they are calibrated in a vertical plane. Any idea how much effect the different orientation will have on the calibration results?
If you can find a calibration laboratory to do this then always try and calibrate to the equivalent of in use conditions. I have just spoken with Young’s, and they do offer both horizontal and vertical calibration installation for anemometers. I think the main issues of calibrating in the wrong plane would be bearing friction effects.
Some helpful wind speed anemometer info.
Be realistic brothers, for what we are trying to achieve calibrating a fume cupboard, is there really a neccesity to go to all the trouble of calibrating the anemometer in the correct plane. Surely the accuracies required negate the need for this
Anemometers calibrated in closed wind tunnel are corrected for blockage effects <50:1 ratio, how does this apply to anemometers calibrated in open jets?
Can anyone tell me what formulae is used for the calibration of S type pitot tubes in air, and dioes this differ for use on other gases. Should we be asking to calibrate the pitot on the gas being used, in this case a cocktail of CO, CO2, NOx, 02 and HC.
Can user adjust calibration of a Type K6010 Vane anemometer, meter is reading low by 5%.
Having problems with calibrating a vane anemometer, nominal 3.5 inches diameter. When positioned in our duct system it consistently reads a high air velocity, but the calibration lab have now calibrated the anemometer twice and report a correctly functioning device. Please advise on any corrections i should be making to correct for air velocity calibration differences to actual air velocity in the duct.
Is your calibration system correcting for blockage Greg. Contact me at papafire@aol.com and I can give you a range of correction factors for rotating vane and cup anemometers, based on our 3 differing wind tunnel types and sizes. This will give you a good guide for air velocity CF, but I would reccomend you spend the time and effort undertaking your own study. We have 3 wind tunnels and a detailed study of a single anemometer will take you 2 -3 days.
We have a calibration room we are currently modifying to become a pressure standards calibration area for low dp sensors. What is the best type of anemometer to measure the air movement in the room. We have issues with the air conditioning, opening and closing doors and personnel movement.
The company commissioning our clean room used a CTA. I think this was from Dantec Dynamics in Denmark. In our final sign off report we were issued with a great 3D velocity profile for our room.
When you have calibrated an anemometer for a customer, could you advise what would be best measurement uncertainty that could be achieved with the said calibrated device, or is this too basic of an assumption. I am trying to achieve a 1% + 0.02 m/s accuracy from my anemometer, which has a calibrated uncertainty of 0.5% + 0.01 m/s, could you advise on what uncertainty components I need to factor into my total budget.
Looking into the feasability of installing a small wind tunnel to calibrate our thermal anemometers and 19 mm vane anemometers. Is it Ok to calibrate the wind tunnel using a gas flowmeter (volume flow deveice), because this traceability issue, is significantly easier for volume flow rate than air velocity, or so I am finding. Let me know if I am going about it the wrong way, but any help appreciated.
Andrew, why calibrate a velocity device with volume flowmeter and then convert back to velocity, this seems a long winded way to achieve your traceability. There are quite a few UKAS calibration laboratories offering air velocity calibration, (goto http://www.ukas.org/calibration and search for velocity). It would be easier to undertake a velocity profile of your tunnel with a UKAS calibrated pitot or thermal anemometer. I prefer to use a pitot, as these are less sensitive to installation misalignment than the thermal type probes. Contact me if you need further help. Regards Baz
What is the best type of anemometer to use, for calibrating a large open duct. We are using a thermal anemometer at present, but it seems very sensitive to hand movement. Are vane anemometers better for calibration use?
If staying over 3 m/s then we use pitot tube; decent pitot has good sensitivity to misalignment. Below 3 m/s we use small vane for site engineers, as easy to correctly align and thermal for best measurement practices, although thermal probe is held in a jig.
If money is no object, then cannot do better than laser doppler anemometer, but these not very portable and take a great deal of expertise in getting setup correctly. I think these guys at Young’s use a laser for calibration, but do not offer this externally away from the laboratory.