Barograph ink and pen

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Thomas Woodford
Posts: 3
Joined: Sun Dec 13, 2015 7:52 am

Barograph ink and pen

Post by Thomas Woodford » Sun Mar 22, 2020 5:58 pm

Hi there,

As a COL member I have recently obtained a Wilson Warden barograph from RMetS, through the Williams bequest. From inspecting the instrument it looks like it may need both a new pen nib and ink.

Is anybody familiar with this type of instrument and able to advise, as I can't find anything very conclusive when searching online to see what types of nib and ink would be compatible.

Also, I'm considering buying a Maximum Proteus Aneroid barometer (possibly from Met Check). Does anybody have experience of using this type of instrument? I note that it is temperature compensated - has anybody any knowledge of how much difference this is likely to make to the accuracy, as compared to a more basic instrument without this feature? I would be wall mounting the instrument within the home, away from radiators and windows.

Any advice or sources of online information would be greatly appreciated.

With best wishes

Thomas (St Ives, Cambridgeshire)

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Len Wood
Posts: 94
Joined: Sat Dec 12, 2015 8:41 pm
Location: 1 km from coast in Wembury, SW Devon

Re: Barograph ink and pen

Post by Len Wood » Sun Apr 05, 2020 10:31 pm

You could try Barometer World.
The chap there is very knowledgeable and sells things for barographs..
http://www.barometerworld.co.uk/
Len
Wembury, SW Devon coast

83 m amsl

Adrian Hudson
Posts: 6
Joined: Sun Dec 13, 2015 7:54 pm

Re: Barograph ink and pen

Post by Adrian Hudson » Fri Apr 10, 2020 6:58 pm

Hi,

Well, that barometer is a nice device. Its stated accuracy is 0.08 inches of mercury, which sounds excellent but sounds less so in millibars - +/- 2.7mb.

Now 2.7Mb isn't bad. The old Met office MkII barometer (which was physically similar to the Proteus) had to be within 2.3 Mb at 1000, 950 and 900mb and had to differ less than 1.7Mb at two different temperatures, room temperature (whatever THAT was) and room temperature +18degF (note F, not C - this was a while ago. The Met Office has many many years ago stopped using aneroid) barometers of course (or even mercury ones). So, all in all as a hobby device the Proteus is okay but not up to modern professional standards.

Much more difficult for the average person is actually SETTING the barometer and here is where most amateurs have problems. The UK standard barometer is in the National Physical Laboratory in Teddington, London. There are few reference barometers around the country that I can find, anyway. I resorted to taking a digital barometer to Teddington (I live in Devon), taking a pressure reading sitting outside and setting the barometer using their website, then when home, calculating the MSL pressure taking my altitude into account and finally setting my various barometers. Phew!

The thing is, barometers drift and aneroid ones should really be set monthly. In fact, the Met office Handbook of Meteorological Instruments (1956) Which is about the correct reference for an aneroid barometer states they should be checked fortnightly! No, I am not going to drive to Teddington fortnightly, I promise you!

If anyone knows a better way of setting a barometer accurately (within, say, 0.5 mb), please let me know!

Thomas Woodford
Posts: 3
Joined: Sun Dec 13, 2015 7:52 am

Re: Barograph ink and pen

Post by Thomas Woodford » Mon Apr 27, 2020 10:11 am

Thanks for your comments.

I was interested to hear that the Proteus has a stated accuracy of 2.7Mb. Not perfect but I think that's good enough for me in terms of making data submissions for the COL website.

Obviously going to Teddington is not not going to be so practical for the foreseeable future. My nearest observing station a few miles from my house in Cambridgeshire is RAF Wyton, and I have been able to set my barograph by checking real-time online readings from there, and also comparing against the live AWS feed from the COL observation station at Little Paxton (distance circa 15 miles) and for further checks, looking at the data for Bedford and the current Met Office synoptic charts. I have been aided by the anticyclonic conditions this month and was able to set my instrument while close to a high pressure centre on 14 April.

What are your views on just setting (for example) a Proteus barometer using the same method as above, then setting the barograph to read the same, then so far as possible, re-calibrating both instruments once per month?

I suspect this is going to be acceptable for most amateur purposes but would be interested to hear if you think it could lead to significant error - for instance, unreliable readings often more than 5mb adrift from other local observations and synoptic charts.

My budget for a barometer is no more than £400 max, ie. about the cost of the Proteus. Does anybody know if I could pick this instrument up cheaper second hand etc (Amazon and eBay don't have it currently!)? Are there any other instruments worth consideration and including some form of temperature compensation?

Thanks again and best wishes

Thomas

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