Author Topic: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD  (Read 17075 times)

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Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #200 on: August 06, 2018, 08:54:21 AM »
Valentine if you want to see the sky conditions click on the banner at the bottom of my post and then click on live web cam at the bottom of the still cam pix and you can see the sky conditions. I changed the upload time to 5 minutes.
« Last Edit: August 06, 2018, 08:57:39 AM by jerryg »

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #201 on: August 06, 2018, 11:04:37 AM »
Yeah i thought about the upload time i might lower it to 5 minutes for test but i am looking at real time here so did not cross my mine. I know, a real bummer, i had 5 days of clear blue skies with light to calm morning winds and seabreeze winds in the afternoon, perfect for testing and no shields  :-( I got just one day and that was afternoon time just before seabreeze hit. I thought i might get a shot this am but clouds and rain already moving in and morning sun is being block by heavy clouds in the east. I would like to get just one good full day of light wind and sun to test things but the weather gods are laughing at me lol.

Good idea at least for length of test we can use the mesowest graph for at least the primary shield.
Randy

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #202 on: August 06, 2018, 04:07:30 PM »
It's early in the test but i have been watching the temps and we finally go sun with calm to low winds for awhile and with calm wind the standard shield was up to 1 degree warmer than the fars and the pro was even with it but as soon as we got a little wind the temps when down on both, the pro down .5 and the standard down about the same. I decided to compare the two shields to each other and generally the pro runs about 1 degree lower than the standard. It looks like the extra black louvers inside the pro is the big difference. Keeping in mind the possible variations between the sensors as long as there is some wind the standard does a good job against the fars and for the price isn't bad. For those that want the most accurate it looks like the pro is the way to go. Right now wind 4 mph pro is .4 lower and standard is .4 higher. The thing is with the fars my dp always seemed to run high and now it is doing fine. Oh yes, i plugged the hole in the tube, the cable was flopping around in the wind so used some foam rubber and plugged it. Now cable is more secure.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #203 on: August 06, 2018, 04:35:29 PM »
In my testing the 31's run about .5F degree warmer than the 15's.
Both the 31 and 15 are in fars only few feet away from each other and this is consistent with the 15 it just runs lower at mid range temps and has similar specs with the 75.

Jerry anything keeping standard shield owners from doing their own flat black interior? Does it split open for access?

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Randy

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #204 on: August 06, 2018, 04:55:17 PM »
A man with a thermometer knows what the temperature is. A man with two thermometers is never sure.  :idea:

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #205 on: August 06, 2018, 04:58:37 PM »
The pro looks like it is put together like the davis plates, stacked with long screws holding them together. The pro is like the standard but with a smaller black louvered shield inside it.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #206 on: August 06, 2018, 05:42:43 PM »
The pro looks like it is put together like the davis plates, stacked with long screws holding them together. The pro is like the standard but with a smaller black louvered shield inside it.

I see, so that's the double shield.
Randy

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #207 on: August 06, 2018, 05:46:29 PM »
Yes that is why the sensor chamber is smaller than the standard, i did not look to much into how the inner shield went into it but i think i would be real careful if i took it apart might be a nightmare to put back together. It looks like you would have to alternate a white then black plate somehow. Should never have to take it apart though if the self cleaning holds up.

Offline Old Tele man

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Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #209 on: August 06, 2018, 06:49:33 PM »
Looks like it could be done. Thanks for bottom few on standard.

I ran across this info, the pro shield compared to highly regarded FARS unit. Max error was .5c or (.9°f).
The 7714 max error against FARS (DAVIS) has been .9C (1.6f). 
If the standard is much worse than the pro I expect the standard to be about the same as the 7714.
That's why we test.
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Bottom of standard
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« Last Edit: August 06, 2018, 06:51:56 PM by ValentineWeather »
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #210 on: August 07, 2018, 05:06:04 AM »
I think it's important inside of these shields be non reflective flat black. Why they didn't' do it on standard shield? Maybe selling point for the more expensive pro model.
Vaisala does their new shields this way, it's almost become a standard now for absorbing accumulated heat thus eliminating the  possible warming inside the shield.

I was testing black spray paints yesterday and figured out you can accelerate the drying time substantially reducing odor by using a hair dryer. I'm going to look at hardware stores today for some Krylon Fusion black silk. This paint claims to work well on plastic and 10 minute dry times. I currently have the Valspar includes primer for plastics which is good quality paint but odor sticks around a day or so.

https://my.vaisala.net/Vaisala%20Documents/Vaisala%20News%20Articles/VN160/VN160_New_Radiation_Shield_Models_DTR502B_and_DTR503A.pdf
Randy

Offline openvista

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #211 on: August 07, 2018, 07:59:25 AM »
I think it's important inside of these shields be non reflective flat black. Why they didn't' do it on standard shield? Maybe selling point for the more expensive pro model.
Vaisala does their new shields this way, it's almost become a standard now for absorbing accumulated heat thus eliminating the  possible warming inside the shield.

I was testing black spray paints yesterday and figured out you can accelerate the drying time substantially reducing odor by using a hair dryer. I'm going to look at hardware stores today for some Krylon Fusion black silk. This paint claims to work well on plastic and 10 minute dry times. I currently have the Valspar includes primer for plastics which is good quality paint but odor sticks around a day or so.

https://my.vaisala.net/Vaisala%20Documents/Vaisala%20News%20Articles/VN160/VN160_New_Radiation_Shield_Models_DTR502B_and_DTR503A.pdf

Problem with spray paints is they are all high in VOCs which is not good for the sensor. You can find reduced VOC spray paint, but it's still not "low" in VOCs and I'd question the quality (flaking).
Davis Vantage Pro2 AC FARS | https://marquetteweather.com | EW7933

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #212 on: August 07, 2018, 08:32:24 AM »
Comparing shields is really a tough thing to do, i was thinking about the davis fars and in their comparison test they state the error was no more than say .6f higher than the rm young but you have to input the rm young also has an error of say .5f so your davis fars error could be over 1 degree and still be in spec. This is why my wondering about the pro readings with some wind blowing always being lower than the fars could mean the pro is closer to the actual temp and the fars is showing that potential 1f degree error. The test you show could be against a really good fars with great specs and that .9 with no wind would be great specs, after all we are talking about a cost effective shield that gives good results unless there is no wind and even then usable temps. We need to keep in mind these test are under the most severe conditions as far as no wind and high isolation conditions which only occur at certain times. Where i live the wind generally blows during the day and only lays at night but with no sun at night no heating effect. So it is really dependent on your location and wind conditions that will determine how well any given shield works. What is good for me may not work for you. Even the best fars have a temp rise error at max isolation and low wind. I was looking at the one they use for the climate network that cost 750 smackers and it has a low but it is there temp error. When it comes to daytime temp readings i use the nighttime temp comparison between the three shields and they never vary more than a tenth at night so any difference during the day is due to the shield itself and how it handles the varying conditions.

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #213 on: August 07, 2018, 08:51:36 AM »
I think that since the pro seems to perform slightly better than my fars i am going to do some head to head comparison between the pro and the standard shields. I will have to put a 75 sensor in the standard shield for the comparison. I guess i could see if what i suspect is that a davis sensor could be cut down to fit inside a pro shield, the worse that could happen is i have a mutilated 31 lol.

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #214 on: August 07, 2018, 09:02:47 AM »
To start still dark and no wind pro and standard showing 73.7  now at 8 am wind 2 mph and sunny skies pro is 79.1 and standard is 79.3 . More later.

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #215 on: August 07, 2018, 09:36:32 AM »
Comparing shields is really a tough thing to do, i was thinking about the davis fars and in their comparison test they state the error was no more than say .6f higher than the rm young but you have to input the rm young also has an error of say .5f so your davis fars error could be over 1 degree and still be in spec. This is why my wondering about the pro readings with some wind blowing always being lower than the fars could mean the pro is closer to the actual temp and the fars is showing that potential 1f degree error. The test you show could be against a really good fars with great specs and that .9 with no wind would be great specs, after all we are talking about a cost effective shield that gives good results unless there is no wind and even then usable temps. We need to keep in mind these test are under the most severe conditions as far as no wind and high isolation conditions which only occur at certain times. Where i live the wind generally blows during the day and only lays at night but with no sun at night no heating effect. So it is really dependent on your location and wind conditions that will determine how well any given shield works. What is good for me may not work for you. Even the best fars have a temp rise error at max isolation and low wind. I was looking at the one they use for the climate network that cost 750 smackers and it has a low but it is there temp error. When it comes to daytime temp readings i use the nighttime temp comparison between the three shields and they never vary more than a tenth at night so any difference during the day is due to the shield itself and how it handles the varying conditions.
You use the stock fan in your FARS, correct? Have you tried comparing 2 Davis FARS -- one with a stock fan and one with more CFMs?

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #216 on: August 07, 2018, 10:06:03 AM »
Yes i did for some time and after having sensor failures because of moisture problems i went back to the davis set up because of the lower fan speed at night. This is the second morning that i have cut the fan off at night and got the same results much better readings in the mornin g that follows the other shields pretty well and not lagging behind for an up to an hour. I really think a fars if pretty tough on sensors in high humidity areas and i plan on running the pro shield for good. At 9 am the standard was 84.6 and the pro was 84.4 with winds 4-6 mph and still sunny.

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #217 on: August 07, 2018, 10:15:31 AM »
Yes i did for some time and after having sensor failures because of moisture problems i went back to the davis set up because of the lower fan speed at night. This is the second morning that i have cut the fan off at night and got the same results much better readings in the mornin g that follows the other shields pretty well and not lagging behind for an up to an hour. I really think a fars if pretty tough on sensors in high humidity areas and i plan on running the pro shield for good. At 9 am the standard was 84.6 and the pro was 84.4 with winds 4-6 mph and still sunny.
It's interesting that you fine the RH lags in the morning with a FARS. Even with dewpoints near 70F, I've always found the opposite.

Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #218 on: August 07, 2018, 10:18:11 AM »
To start still dark and no wind pro and standard showing 73.7  now at 8 am wind 2 mph and sunny skies pro is 79.1 and standard is 79.3 . More later.
Just saw CRP is 83/81 right now. I don't know how you guys handle that down there.

Offline hwcorder

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #219 on: August 07, 2018, 10:30:49 AM »
I have had my modified 75 in a  Meteoshield Pro for several days now with the stock Davis filter.  Here is my station dw5686 if you want to follow along with my stats compared to MADIS and two ASOS stations one 5 miles east (CLT) and the other 8miles southwest (AKH). I also upload to WxUnderground if you want to follow my data more in real time.

https://weather.gladstonefamily.net/site/D5686
https://www.wunderground.com/personal-weather-station/dashboard?ID=KNCBELMO18#history

So far I'm very happy as it seems my CWOP stats haven't changed very much at all. Perhaps running just .2F to .3F warmer compared to other stations than I used to. When comparing highs and lows I to local ASOS I go back and look at my one minute data and find the 5min running avg for the high and low for the day.  I think this is important that you do this since when comparing your readings with ASOS as it smooths out temperature data this way.  Anyhow, I have been running either even or one degree cooler than my local ASOS stations which is on par when I was running a davis FARS with stock fan, actually the replacement 3V motor from Nichibo.

Weather has been great for testing except for cloud cover.  Hot humid afternoons with light winds, but with scattered to broken layers. Want to eventually get around to some side by side testing with my FARS but from what jerryg has found in his testing it sounds like both the meteoshields and especially the pro may be promising alternatives to aspirated shields.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #220 on: August 07, 2018, 10:32:22 AM »
To start still dark and no wind pro and standard showing 73.7  now at 8 am wind 2 mph and sunny skies pro is 79.1 and standard is 79.3 . More later.
Just saw CRP is 83/81 right now. I don't know how you guys handle that down there.

I've lived on the gulf before when I was a kid and remember it was the only place I sweated alot...Absolutely there is no evaporation so any moisture turns into liquid. 
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #221 on: August 07, 2018, 10:57:31 AM »
I think it's important inside of these shields be non reflective flat black. Why they didn't' do it on standard shield? Maybe selling point for the more expensive pro model.
Vaisala does their new shields this way, it's almost become a standard now for absorbing accumulated heat thus eliminating the  possible warming inside the shield.

I was testing black spray paints yesterday and figured out you can accelerate the drying time substantially reducing odor by using a hair dryer. I'm going to look at hardware stores today for some Krylon Fusion black silk. This paint claims to work well on plastic and 10 minute dry times. I currently have the Valspar includes primer for plastics which is good quality paint but odor sticks around a day or so.

https://my.vaisala.net/Vaisala%20Documents/Vaisala%20News%20Articles/VN160/VN160_New_Radiation_Shield_Models_DTR502B_and_DTR503A.pdf

Problem with spray paints is they are all high in VOCs which is not good for the sensor. You can find reduced VOC spray paint, but it's still not "low" in VOCs and I'd question the quality (flaking).


I've checked for low VOC spray paint for plastic and can't find any.
What I read about the VOC's once paint is dry they stop emitting but it could be days maybe weeks depending.   One of the checks sensirion mentioned was if odor is present especially strong it can damage humidity sensor.
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #222 on: August 07, 2018, 11:09:50 AM »
This is why my wondering about the pro readings with some wind blowing always being lower than the fars could mean the pro is closer to the actual temp and the fars is showing that potential 1f degree error.

The WMO test on page 1 knocked the Davis FARS shield down for reading warmer vs reference shield with wind. Not sure how much wind it takes before the weak fan wouldn't work. Not much is my guess.

You need all 3 shields with exact sensor so 2 more 75's for a good comparison. However problem is 11 and 15's never matched exact and the 75's not sure :?:  Different story with the SHT31's they all seem to match within .02f.
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #223 on: August 07, 2018, 12:15:15 PM »
I have had my modified 75 in a  Meteoshield Pro for several days now with the stock Davis filter.  Here is my station dw5686 if you want to follow along with my stats compared to MADIS and two ASOS stations one 5 miles east (CLT) and the other 8miles southwest (AKH). I also upload to WxUnderground if you want to follow my data more in real time.

https://weather.gladstonefamily.net/site/D5686
https://www.wunderground.com/personal-weather-station/dashboard?ID=KNCBELMO18#history

So far I'm very happy as it seems my CWOP stats haven't changed very much at all. Perhaps running just .2F to .3F warmer compared to other stations than I used to. When comparing highs and lows I to local ASOS I go back and look at my one minute data and find the 5min running avg for the high and low for the day.  I think this is important that you do this since when comparing your readings with ASOS as it smooths out temperature data this way.  Anyhow, I have been running either even or one degree cooler than my local ASOS stations which is on par when I was running a davis FARS with stock fan, actually the replacement 3V motor from Nichibo.

Weather has been great for testing except for cloud cover.  Hot humid afternoons with light winds, but with scattered to broken layers. Want to eventually get around to some side by side testing with my FARS but from what jerryg has found in his testing it sounds like both the meteoshields and especially the pro may be promising alternatives to aspirated shields.

Very nice so another with a pro.

Has me thinking do I want to change at least 1 shield coming to a pro?
Randy

Offline ValentineWeather

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« Last Edit: August 07, 2018, 03:12:34 PM by ValentineWeather »
Randy

 

anything