Author Topic: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD  (Read 6882 times)

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #25 on: July 27, 2018, 02:26:49 PM »
Has anyone else tested one of these?

https://www.baranidesign.com/meteoshield-professional/

I've had mine in for about three days and happy with the results. Stats from MADIS have held about the same compared to ASOS station close to me and the last two days have been mostly sunny and fairly light wind. The shield is expensive for a passive and definitely more than the 7714. It's supposedly designed to protect the sensor from contamination in the way airflow is directed inside the chamber.
Edit: Forgot to add you will have to do some engineering to get the Davis sensor to fit.

Can you get the SHT31 inside?  I was going to be involved with testing these but they never got back after I gave them all information.

I made the mistake of posting a thread here and had a few negative post about persons with no interest in a passive shield and never heard back from them again.

They quietly pulled their development of their VP2 compatible shield. They were trying to use a probe and couldn't get it connected to the SIM. My guess is Davis won't sell their sensors to a competitor so they tried their own solution and couldn't get it to work.
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Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #26 on: July 27, 2018, 02:37:42 PM »
Has anyone else tested one of these?

https://www.baranidesign.com/meteoshield-professional/

I've had mine in for about three days and happy with the results. Stats from MADIS have held about the same compared to ASOS station close to me and the last two days have been mostly sunny and fairly light wind. The shield is expensive for a passive and definitely more than the 7714. It's supposedly designed to protect the sensor from contamination in the way airflow is directed inside the chamber.
Edit: Forgot to add you will have to do some engineering to get the Davis sensor to fit.

Can you get the SHT31 inside?  I was going to be involved with testing these but they never got back after I gave them all information.

I made the mistake of posting a thread here and had a few negative post about persons with no interest in a passive shield and never heard back from them again.

They quietly pulled their development of their VP2 compatible shield. They were trying to use a probe and couldn't get it connected to the SIM. My guess is Davis won't sell their sensors to a competitor so they tried their own solution and couldn't get it to work.

I see.  :-(   I spent time with them sent images measurements etc. and never heard back after the initial first couple weeks.
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Offline hwcorder

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #27 on: July 27, 2018, 03:18:48 PM »
Has anyone else tested one of these?

https://www.baranidesign.com/meteoshield-professional/

I've had mine in for about three days and happy with the results. Stats from MADIS have held about the same compared to ASOS station close to me and the last two days have been mostly sunny and fairly light wind. The shield is expensive for a passive and definitely more than the 7714. It's supposedly designed to protect the sensor from contamination in the way airflow is directed inside the chamber.

My problem with it is it's designed for a probe sensor and is completely open at the bottom letting in reflected radiation. I'm thinking of snow albedo and longwave radiation at night, in particular. Plus, isn't it something like $500 just for the shield?

The only opening on the bottom is for a probe type opening. Like I said you have to do some engineering to get a Davis to work. This is actually kind of a double shield with the outer being white and the inner being black to protect against longwave radiation loss at nigh

Seems like I saw a test somewhere where they compared this shield over a snowpack and it outperformed some FARS units. Will have to see if I can find it though.
As far as pricing I think I got it for around $250.

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #28 on: July 27, 2018, 03:22:05 PM »
More AWOS goodness. This is from another All Weather Inc. document seen here: http://www.allweatherinc.com/wp-content/uploads/AWOS-III-PTHU-Specification-1505220-16-Latest-Edition1.pdf

Quote
The relative humidity sensor shall be
thermally  isolated  in  a  motor  aspirat
ed  radiation  shield
  to  accurately 
measure the atmospheric
dew point temperature.

This is for the AWOS III P/T which is used at my local airport KSAW.

So if the reason for investigating passive shields is because fan aspiration is not "best practice" for humidity measurement, this may not be completely true. Also consider that many highly accurate analog psychrometers now use aspiration. Plus, consider the research concluding that passive shields create an artificially wet environment in low wind situations.

Unfortunately, there's no perfect solution. I can certainly appreciate the "wear & tear" consideration on sensors subjected to extra air and moisture crossing them due to active ventilation, especially if your sensors can be adequately passively ventilated. In the end, I suppose we all choose according to our unique priorities.
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Offline kcidwx

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #29 on: July 27, 2018, 03:24:52 PM »
Here, I took a couple photos of the ASOS DTS1 sensor/shield. The weeds are gone now but my allergies aren't  :lol:



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Offline hwcorder

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #30 on: July 27, 2018, 03:28:42 PM »
Has anyone else tested one of these?

https://www.baranidesign.com/meteoshield-professional/

I've had mine in for about three days and happy with the results. Stats from MADIS have held about the same compared to ASOS station close to me and the last two days have been mostly sunny and fairly light wind. The shield is expensive for a passive and definitely more than the 7714. It's supposedly designed to protect the sensor from contamination in the way airflow is directed inside the chamber.
Edit: Forgot to add you will have to do some engineering to get the Davis sensor to fit.

Can you get the SHT31 inside?  I was going to be involved with testing these but they never got back after I gave them all information.

I made the mistake of posting a thread here and had a few negative post about persons with no interest in a passive shield and never heard back from them again.

They quietly pulled their development of their VP2 compatible shield. They were trying to use a probe and couldn't get it connected to the SIM. My guess is Davis won't sell their sensors to a competitor so they tried their own solution and couldn't get it to work.

I'm planning on making my own probe using a magic marker casing a 4pin connector and an sht75. Will also get a filter from Campbell scientific or Vaisala to put on top.
« Last Edit: July 27, 2018, 03:31:59 PM by hwcorder »

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #31 on: July 27, 2018, 03:29:39 PM »
Here, I took a couple photos of the ASOS DTS1 sensor/shield. The weeds are gone now but my allergies aren't  :lol:

OK, just to clarify, this is for an ASOS system? But, apparently, the more modern AWOS's, or some subset of them, aspirate the humidity sensor, at least according to the documentation.
« Last Edit: July 27, 2018, 03:42:12 PM by openvista »
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #32 on: July 27, 2018, 03:50:04 PM »
My problem with it is it's designed for a probe sensor and is completely open at the bottom letting in reflected radiation. I'm thinking of snow albedo and longwave radiation at night, in particular. Plus, isn't it something like $500 just for the shield?

The only opening on the bottom is for a probe type opening. Like I said you have to do some engineering to get a Davis to work. This is actually kind of a double shield with the outer being white and the inner being black to protect against longwave radiation loss at nigh

Seems like I saw a test somewhere where they compared this shield over a snowpack and it outperformed some FARS units. Will have to see if I can find it though.
As far as pricing I think I got it for around $250.

I stand corrected.

I'll be interested to see what you come up with in the end to mount the 75 in there. It would deserve its own thread. I, too, have been quite curious about whether this shield can live up to the claims.
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Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #33 on: July 27, 2018, 04:02:55 PM »
The ASOS DTS1 humidity sensor sure is exposed for a good air sample.
 
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #34 on: July 27, 2018, 04:08:25 PM »
Here, I took a couple photos of the ASOS DTS1 sensor/shield. The weeds are gone now but my allergies aren't  :lol:

OK, just to clarify, this is for an ASOS system? But, apparently, the more modern AWOS's, or some subset of them, aspirate the humidity sensor, at least according to the documentation.

Yes, they do. I've worked on the AWOS III-PT. Unless they have done something custom it doesn't use separate sensors for temperature and humidity. It uses a combination 5190-F temperature/humidity sensor inside the 8190 MARS.

« Last Edit: July 27, 2018, 04:20:55 PM by kcidwx »
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #35 on: July 27, 2018, 04:29:41 PM »
Yes, they do. I've worked on the AWOS III-PT. Unless they have done something custom it doesn't use separate sensors for temperature and humidity. It uses a combination 5190-F temperature/humidity sensor inside the 8190 MARS.

Interesting!

My local airport, KSAW, seems to run about 2-3 degrees low lately in dewpoint as compared to other airports/RAWS stations. Just checked the spec and max error is 3F between +30 and +90F. So, I guess they're within spec!

Do the AWOS IIIP/T capacitive sensors tend to drift noticeably and, if so, which direction is typical?

Also, any idea of the aspiration rate (m/s, cfm, whatever)?
« Last Edit: July 27, 2018, 04:55:28 PM by openvista »
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #36 on: July 27, 2018, 05:13:29 PM »
Nice info in this thread. Thanks guys.


KCID...do you have any spec documentation for the DTS1? I can't find much through Google.

Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #37 on: July 27, 2018, 05:22:19 PM »
Emailed Ryan about being out of the 7714 he said business has been steady for long time, especially in Canada hard to keep them in stock. Backordered again.
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #38 on: July 27, 2018, 05:36:48 PM »
Emailed Ryan about being out of the 7714 he said business has been steady for long time, especially in Canada hard to keep them in stock. Backordered again.
Have you tried contacting Bob Ingham at Rainman Weather?
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Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #39 on: July 27, 2018, 06:14:09 PM »

Have you tried contacting Bob Ingham at Rainman Weather?

No, I'm good for now on shields I was just asking Ryan because few days ago he had more stock in.

Noticed Rainman has the originally Stratus gauge at killer price. $29 + shipping.
Lot's of knockoffs of the gauge now days. Wish someone would make the gauge more accurate and deepen the funnel by couple inches.
That was my first 4" diameter gauge back in 1976.  I think I paid more back then... :roll:
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #40 on: July 27, 2018, 06:18:01 PM »
I purchased my first VP2 from Rainman back in the day. I've also gotten some parts here and there from them. Good, fast service. But I see they don't stock the 7714.

If anyone is in a yank, I'd try scientificsales.com. I've had good luck with them too. I think SS includes shipping in their prices, which is why they seem higher. So don't compare on unit price alone. Shipping just keeps going up and up!
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #41 on: July 27, 2018, 06:55:53 PM »
Was hosing off my ISS to get some of the dust off of it and got water into the chamber and killed my 67 CFM fan. Ordered another but will take faaar too long to get here, so went and bought one that's "only" 40 CFM from down the street, cause this boy ain't doin' without a fan. Thing's really quiet compared to the other, Ill probably just leave this weaker one in.
GL to all the passive efforts!

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #42 on: July 27, 2018, 08:17:11 PM »
Was hosing off my ISS to get some of the dust off of it and got water into the chamber and killed my 67 CFM fan. Ordered another but will take faaar too long to get here, so went and bought one that's "only" 40 CFM from down the street, cause this boy ain't doin' without a fan. Thing's really quiet compared to the other, Ill probably just leave this weaker one in.
GL to all the passive efforts!

If only you had two ISS's to compare to. I wonder how much temp difference there might be between using a 67 and 40cfm fan, if any.
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #43 on: July 27, 2018, 08:24:42 PM »
Was hosing off my ISS to get some of the dust off of it and got water into the chamber and killed my 67 CFM fan. Ordered another but will take faaar too long to get here, so went and bought one that's "only" 40 CFM from down the street, cause this boy ain't doin' without a fan. Thing's really quiet compared to the other, Ill probably just leave this weaker one in.
GL to all the passive efforts!

If only you had two ISS's to compare to. I wonder how much temp difference there might be between using a 67 and 40cfm fan, if any.
I see zero difference, nor did I expect to. 67, although overkill, worked just fine, so will 40, even if it's overkill too. I'll take it.

Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #44 on: July 27, 2018, 09:06:17 PM »
 I'm removing this graph because I was using a modified shield which was running warmer. Rest of test will include stock shield with fan.

 
« Last Edit: July 28, 2018, 01:20:58 PM by ValentineWeather »
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #45 on: July 27, 2018, 09:46:30 PM »
First full day lots of clouds even a thunderstorm with passive once again slightly cooler vs FARS. Couple things morning warm up showed some lag vs FARS red arrow and the fars was more jagged with dew point.  I hate that when we are in high heat index area and it spikes.

 
Looks like it's right in line with the FARS with just a slower response. I see no problem with the jagged dewpoint graph. To each his own though. Pretty sweet performance by the passive though...clouds or not. What did your winds average?

Offline ValentineWeather

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #46 on: July 27, 2018, 09:56:01 PM »
First full day lots of clouds even a thunderstorm with passive once again slightly cooler vs FARS. Couple things morning warm up showed some lag vs FARS red arrow and the fars was more jagged with dew point.  I hate that when we are in high heat index area and it spikes.

 
Looks like it's right in line with the FARS with just a slower response. I see no problem with the jagged dewpoint graph. To each his own though. Pretty sweet performance by the passive though...clouds or not. What did your winds average?

Thunderstorm peaked into 20's it dropped .24" put mainly went west of town.
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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #47 on: July 28, 2018, 12:48:55 AM »
My results with the 7714 compared side by side to the stock 24hr FARS are pretty much right on with ValentineWeather. Maybe itís the latitude? Iím a FARS fanatic too and almost didnít want to believe it as it seemed counterintuitive.  I went with the 7714 recently because I just moved and my yard presents unique circumstances. The results of the side by side made it easier to swallow.

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #48 on: July 28, 2018, 06:08:03 AM »
My results with the 7714 compared side by side to the stock 24hr FARS are pretty much right on with ValentineWeather. Maybe itís the latitude? Iím a FARS fanatic too and almost didnít want to believe it as it seemed counterintuitive.  I went with the 7714 recently because I just moved and my yard presents unique circumstances. The results of the side by side made it easier to swallow.

I know the feeling. I've always defended and said it's the only way to go and now I'm wondering what's going on.
I've tested passive units before just not this one. The VP2 passive always ran +2 even +3į with light wind speeds. 

Is this correct thinking with tilt of earth summer sun angle is actually more intense northern latitudes vs southern latitudes? If so that can't be an issue on testing.
I know it's different here vs Arizona, sunsets far NW where Arizona it was more west.  Here sunlight is 1+ hours longer also.
I see a 90įF day on the 10 day forecast hope wind speeds are light.
Randy

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Re: WMO field study thermometer shield FARS 7755, Passive 7714
« Reply #49 on: July 28, 2018, 10:39:47 AM »
Something i have been wondering is i have read a lot about the inside of shields being painted black to absorb radiation inside of the shield and white on the outside to reflect the solar effect. Most of the studies show a positive effect so why aren't more of the shields on the market made that way? The only reason i can think of is cost?