PVC Anenometer Mast

[krmidas]

Anyone have experience with using PVC pipe as an anenometer mast?

I attached a 10' PVC pipe (painted to retard UV damage) to a wooden mailbox post. The pipe is the same diamater as the mounting pole that came with my Pro Vantage 2, so I was able to use all the same mounting hardware.

My concerns/questions are:

-has anyone else tried this?

-there is some minor swaying at the top, but it doesn't seem to adversely affect the wind readings

-how does the PVC hold up in extreme weather? In the Chicago area, we get summer temps that reach the upper 90's F, and winter temps that plunge to -15 F. I'm concerned that the pole might snap in half during a bitter cold spell.

I've done some general research, and it seems like some folks have endorsed the PVC approach. You can't beat the price (my 10' section cost $3 at my local Home Depot), or the weight. It also takes paint well, and is easily lowered for maintenance.

Any thoughts?

-Tom

[Super-T]

I found a length of square section, 40mm, aluminium extrusion works well. 5 metres long and mounted on the top deck so it is reasonably clear of trees and rooftop. I would think that plastic round section would move around quite a bit.

[captzero]

Tom,
I think you are on to a winner there. PVC is often used in the construction industry because it's is resistant to weathering, chemicals, rotting and corrosion etc and it's cheap. My anenometer mast is a 10 foot length of "stainless steel" tubing that is slowly showing signs of corrosion and I will probably replace it soon. PVC is easy to work with and lightweight and may not be as attractive to the occasional lightning strike.

[Gina]

I've always found PVC pipe to be very flexible. Or at least what we have in the UK is, maybe yours is different. I'm currently using galvanised iron pipe for the bottom half and copper water pipe at the top but I have some corrosion resistant aluminium tube with which I plan to replace it when I get round to it (after I finish my observatory, probably).

[Super-T]

Gina. You might get corrosion at the joint....dissimilar metals and all that?

[Gina]

Yes I know, it's only temporary, though it's been up quite some time now The new ali mast will be a lot better.

[serowe]

PVC piping will need to be internally supported.

At a minimum you need guy wires completely restricting movement at the top of the pip BUT, because it is a hollow tube, it can not only move side to side (OK around and around) but can also bow in the middle which means the height at the top could, in strong winds especially, decrease as well as change the overall angle of anything mounted on top.

You would also need to ensure the guys pirce the pipe - you can't use a collar of any kind otherwise you will run the risk of the pip literally rotating around thus causing the anemometer to mgrate from its N/S orientation over time.

[Gulfcoast]

I use galvanized water pipe for mine... it's real tough and costs more upfront, but will last for 50-years or more.

[MickinMoulden]

I went through the local hardware store checking all the options. My thoughts were that the PVC is a bargain, but the swaying concerned me and found that the tubular aluminium was nearly as bad, but the square aluminium was far superior in resisting swaying (barley any). Swaying will have some effect on wind direction (untested, just educated guess), although I wouldn't recomend PVC if your water gauge is on it (wouldn't recommend it on a pole in any case - right guys!).
If your looking for a bargain, go to a dump shop of sorts, and get square tubing. A job worth doing is a job worth doing right.

[Super-T]

Yes, the square section works well for me with no guy ropes required. I image a triangular section would work as well if not better than square but it's a bit hard to find a triangular extrusion over 5 metres long
Triangular would be less wind resistance too.

[Gina]

I was very interested in the comparison between round and square aluminium tube. I thought round tube would be better, which is why I bought it. I'm using it for my no.2 mast carrying my 1-wire weather sensors, but it's mounted with the lower end about 2m above ground and is only 5m high (above that). Though it's only about 1.5" diameter. I have 2" tube for the replacement mast bottom section with 1.5" for the top. I shall be ordering aluminium channel for my roll-off roof observatory so might see about some square tube. But I might just get the round mast replaced before then and see how it goes. It will have to be free standing - there isn't room for guys.

[serowe]

With heights of 5 metres be very very careful if you are using guys of any type - yuo are (figuratively) asking for trouble.

I would also be very surprised if you can legally put up anything at that height without staying them properly - not to mention the effect it could have on your insurance (for example nullifying it if any damage is caused by such a pole).

There is a tremendous amount of force placed on the bottom of anything this length and, without guys, the chances of them either bending/snapping or simply pulling the bottom brackets out of whatever they are mounted on to greatly increases.

[Gina]

As I understand it, in the UK you need planning permission for an stayed mast but not for a free standing mast of less than a certain height (10m or 30ft I think). Yes, I know the support at the bottom needs to be very substantial. Current no.1 mast is secured onto a 4" square fence post which is concreted into the ground. Fence post is over 4ft high and mast is 20ft high (6.3m).

[Super-T]

The trick is to avoid any pressure points if possible and no holes to weaken it. We have been having a few gales lately and no problems. My square aluminium tube is tied to the stair railing with a couple of bootlaces. Easy to remove. There is also 1 screw right at the bottom to keep it sitting on a wood shelf.

[GraemeT]

I've used a 5metre length of 32mm aluminium tubing. It's mounted 2 metres up, stabilised using three 2mm stainless guy ropes.
Still waiting to see if it works as a lightning attractor...so far, so good.