Using PVC for weather station mast

[pete_c]

Trying something today and wondering if anybody is using PVC for an outdoor mast.
 
I currently have my Davis Vantage Vue on a J-mast.  Its not high enough.
 
I want to add a 6 foot piece of PVC to it to make it a bit higher.
 
Thinking maybe of doing a 1.25" piece of PVC going to a 1.5" 6 foot PVC and putting the Vantage Vue on top of it.
 
 
 
 

 

[tmbrown97]

Someone on the Chat has his on PVC - about 16' up; he said anything under 2" is too thin and flexes too much.
 
That said I've done exactly the same thing with one of those mounts to get a backhaul radio above a roofline using PVC and in the end it did work out quite well - but I think it was 2" I used there too.  

 

[pete_c]

Thanks guys!
 
Will purchase a 2" PVC tomorrow and give it a try. 

 

[sda]

I would use EMT over PVC.   Even 2" sched 40 will warp over time.  And PVC, white or gray, has a tendency to sunburn if you don't paint it.

 

[Madcodger]

And what about UV degradation over time? I just don't know specs on that, but it's something to consider from a structural perspective.

 

[Neurorad]

Nothing will last forever.

Schedule 80 PVC is sturdier than 40 (thicker wall).

I don't know if motion will affect your sensors. More rigid may help that too.

 

[pete_c]

Thank's guys.  I have read also to purchase a piece of muffler pipe from a muffler shop and have it cut.
 
I do have PVC piping up from a weather station, GPS antenna, lightning sensor et al on the roof.  Its been some 10 years now and not showing any degradation that I can tell.  I did read that schedule 40 PVC is better made these days?
 
The second newer weather station (Davis Vantage Vue) placement was configured for easy access (which really is not that easy anyways).    In order to get to my original weather station mast I just climb up the roof.  Getting down back to the ladder though I have to slide to the gutter (which I do not like doing).  That and the wind has knocked down the fiberglass ladder while I have been on the roof once before.
 
Off on a tangent here....
 
Researching some more ran into discussions relating to design flaws with the incorporation of the rain tipping bucket with the rest of the instruments on the device.  It was something relating to the device just vibrating and tripping the tipping cup.  Part of this is relating to the ideal mounting of a rain bucket should be closer to the ground - 5-6 feet.  That said I do have a larger old Dallas rain tipping bucket that I utilize.
 
I have been comparing numbers from the now 4 rain tipping devices outside and the non mechanical digital rain tipping bucket is too sensitive and doesn't really provide me with good numbers.
 
For use with the Davis Vantage Vue; I will need to reduce the top of the 2" PVC to 1.5 " PVC to connect to the bottom bracket of the Davis Vantage Vue.
 
I am guessing right now that the inner diameter of the 2" PVC will fit over the J-Mount pipe easily (guessing).  Just wanting to get some better wind speed indications here.  Funny as it appears that two of the rain cups were chewed off by a bird or they just broke off.  I was going to paint the PVC grey to match the J-Mast.  (Its already become a WAF issue?).

 

[BraveSirRobbin]

Some thoughts;
 
As long as you paint the PVC you should be OK as far as UV resistance.  I would consider some EMT conduit, depending on your mounting scenario as already suggested above.  I did this for my mount, even custom bent it so it would mount on my slanted wood side and go over some tiles (just used a couple of conduit clamps for the mount).  Painted it black an it has a professional look (poor pic enclosed, I can get a better one if you would like).
 

 
Rain gauge measurement can be tricky.  I believe there should be a method to calibrate your bucket (I know there is for the high end buckets).  It is dependent on the diameter of the collection top surface and will involve measuring a volume of water (graduated cylinder) and pouring it into the bucket while counting the tips.
 
Collection can be heavily influenced by wind, so much so that professional installations prone to high winds have shields that go around the buckets to prevent updrafts.  Also, the tipping mechanism could have its balance possibly disturbed over time (handling, age, etc...).
 
You also need to ensure your tipping buckets are balanced.
 
Also, if the rate is to high, counts may be missed (again the high end buckets have a mechanism to ensure the rate hitting the buckets prevents this).
 
How much are your disparities (in 0.01" increments)?
 
EDIT:  This article has some interesting notes on calibrations.

 

[pete_c]

Thanks BSR. 
 
I haven't paid that much attention between the Dallas Rain Tipping bucket and the Davis Vantage Vue tipping bucket.   The numbers "seem" OK.   
 
Many years ago I did recalibrate the Dallas Rain bucket using a set amount of liquid counting drops and bucket tips.  I haven't touched it / calibrated it now in a few years.  The Davis Vantage Vue bucket appears to be calibrated and sealed so as not to touch it.
 
Guessing the Davis console takes into consideration some of the discrepancies with the maybe movement from wind on the rain tipping bucket (that is me thinking optimistically).  I did see some heated debates on some weather forums relating to international / domestic weather station standards relating to "official" methodologies utilized for weather station device placements and the whole rain tipping bucket stuff being at ground level and separated versus an all in one device.  I do utilize the rain bucket today for creation of the ET / sprinkling factors stuff.

 

[BraveSirRobbin]

This is getting a bit off topic, but in one of my previous endeavors, I had to deal a bit with these professional units.  IMO, RGTB are the anti-Christ!  Of all the sensors we deployed (solar, wind, humidity, temp, baro) these (simple in theory) units were the most problematic. :nutz:
 
I never understood the concept of mounting one on a pole, as all the pro installations are on the ground or at least on a very secure platform.  Just for grins   here is a pic of a professional mount (including the wind screen I mentioned above). 
 

 
Note the pad poured just for this unit!
 
Here is the inside of that RGTB.
 

 
Nowadays rain gauge measurement can be done without any moving parts (again on a pro level).  Vaisala makes a nice all in one unit (temp, humidity, wind, rain) that counts the drops (and size) as it hits the sensor.  Pretty neat technology!  Wish they had this available back then...
 
Of course, most home automation purposes just want a very rough approximation of rainfall, and the cost of getting more accurate readings is cost prohibitive.
 

 

[pete_c]

Thank-you BSR.
 
Yup tested the Digital RG-11; albeit two of them over the last couple of years.  Very sensitive but numbers are not that close to the rain tipping bucket.  Wind though affects little droplets on the plastic dome covers.
 
http://www.rainsensors.com/
 
There are configuration parameters on the Cumulus software for additional rain sensors; IE: Davis via console or direct RS-232 single cable two RG-11's.
 
The current Dallas Rain Tipping bucket is some maybe 6 foot up.  It is mounted on a 6X6 post on the deck right now.  That said I do have the issue relating to the sprinkler system.
 
We have snow coming here and I am still working on the J-Mount pieces for the Davis Vantage Vue.  Pushing this endeavor a bit now.
 
The 2" PVC appears to be a be too large diameter wise to fit over the J-Mast pipe as its about 1.5".  Now sort of doing a mix and match glue thing.  I did buy paint this morning. 
 
I didn't take the J-mast bracket down and working on a ladder for the extension pieces.  Test fitting the PVC pipes and maybe just drilling one small sheet metal set screw to hold the PVC in place.
 
Next though I want to carry up the assembly with the weather station on it (carefully) and just mount it on the mast.  The weather station is actually lighter than the PVC mast though.