Thanks Jack for having me back on the blog. Hopefully I’ve got something here suitable for your readers on both sides of the fence to use to help make sure that every one is playing by the rules.
In October last year I outlined different potential methods for measuring the speed of rotation of frost fans. This was in a follow up to my post on what needs to be measured to ensure compliance, where I backed a system of measuring the speed of rotation to confirm compliance with an accepted level of noise (established by expert testing as part of the commissioning process for a model of fan).
While I outlined several different techniques in theory, I did not have a workable solution for any. I now do.
I have prepared a paper on how to measure the speed of a frost fan and by doing so establishing its compliance with an established noise level.
This method uses a video camera to capture the fans motion and software to measure the rotation. This is a technique that can be carried out relatively easily, at good distances (I have measured fans at over 830 metres distance) and with a high degree of accuracy (the paper describes two additional different measurements that were carried out in order to confirm the rotation of a fan to verify accuracy).
This described method can be carried out at night time with the application of sufficient illumination and provides a record of evidence of whether the activity is compliant or not.
I have measured approximately a dozen fans thus far and have found the technique becomes easier after a bit of practice.
I have published this under the GNU Free Document Licence which gives people the right to freely copy and distribute it with the proviso that is cannot be modified without ensuring that the free nature of the document continues (at least that’s what the legal fraternity seem to believe). In other words, it’s free to use and if you want to use it as the basis for future work on the topic, this must be free also.
If there are questions on the technique, feel free to leave them in the comments section.
The paper can be downloaded from here. (1.7MB download)
1 comment:
Thanks Malcolm,
That's quite a read. I knew you were doing something, and that looks pretty thorough. I see that the fan you measured is rotating faster than permitted under the district plan. Have the Council been made aware of this transgression?
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