Got pics of your PVC pipe water tanks?

Anything and everything in the world of 4WDing & Fourby's; if it's 4WD related & not covered by a specific section elsewhere, then put it in here!
ridgey
Here and there
Posts: 22
Joined: July 22nd, 2009, 11:16 pm

Got pics of your PVC pipe water tanks?

Unread post by ridgey » April 4th, 2017, 2:47 pm

howdy all,

have been tinkering with ideas of where I am going to mount some water tanks on my 80 series and settled on under the front of the roof rack near the windscreen. I have measured up and reckon I can get 3 x 100mm or 90mm PVC about 1.1m long.

I'm sure I'm not the first to do something like this, keen to see some pics of what others have done, end caps, taps, filler caps, how its fixed to roof rack etc

cheers in advance

Peter Aawen
Admin
Posts: 20778
Joined: June 17th, 2005, 8:01 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by Peter Aawen » April 4th, 2017, 5:52 pm

Just be aware that if you mount water pipes across the vehicle up high like you've mentioned, you will increase the lurching & sideways rolling potential of your vehicle due to the 'free surface effect' & the extra weight carried up that high - it could be uncomfortable or possibly even downright dangerous! :eek:
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

ridgey
Here and there
Posts: 22
Joined: July 22nd, 2009, 11:16 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by ridgey » April 4th, 2017, 7:41 pm

im only talking a few litres, maybe 20kg in weight. ive seen lads getting around with 8" lift, 6 jerry cans, 2 spare tyres and a big cargo box full of crap

Peter Aawen
Admin
Posts: 20778
Joined: June 17th, 2005, 8:01 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by Peter Aawen » April 4th, 2017, 8:04 pm

You are right, there are people with a lotta weight up high that will un-balance things somewhat, but it's usually static load & not in a pipe laid across the roof. :purplex:

Your idea is not without merit, altho it might still need some tinkering & maybe a bit of revision, but like I said, you do need to be aware that by putting fluid inside a pipe laid across the roof, it means it hasta be absobloodylutely FULL ALL THE TIME or it'll slop from one side to the other & have a FAR GREATER un-balancing effect than the same static weight at that height!! There is a formula for working out how bad a given weight up there can be, but I can't remember it off the top of my head & besides, I'm too tired to do maths tonight anyway!! So please, just take it as read that 20kgs of 'free surface effect' from surging fluid crossing the roof is WAAAAAaaaaaaaaaayyyyyyyyy worse than just about any static load your roof will hold up there without collapsing!! And it can be a whole lot worse again than that if you've got a lift & flexy suspension!! :boggle:

Look up 'Free surface Moment' & 'Free surface effect' if you want more specific & knowledgeable info than anything I can post (there's also lots of interesting stuff on 'slosh dynamics' & spacecraft propellants that's applicable to road vehicle tanks :frog: ) but it is definitely there & of concern if you are laying tubes/pipes to hold fluids across your roof, & that means it will contribute to making your vehicle more unstable than the same given weight in static loads up at that height! Just sayin' :o
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

ridgey
Here and there
Posts: 22
Joined: July 22nd, 2009, 11:16 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by ridgey » April 4th, 2017, 8:53 pm

hmm i see what you are saying. Is it only horizontal a problem? ( a pipe laid side to side ), if i was to mount it length ways along the side of the roof rack front to back, would it have the same negative impact as side to side?

Peter Aawen
Admin
Posts: 20778
Joined: June 17th, 2005, 8:01 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by Peter Aawen » April 4th, 2017, 9:48 pm

Lengthways ie tanks running along the sides/length of the vehicle will have significantly less free surface impact than those running across the vehicle, cos the free surface effect then will impact most fore & aft, ie along the greater length between the front & rear wheels rather than between the shorter length across between the left & right wheels. So maybe if you fitted pipes along the sides of vehicle roof rack you'd only want to avoid really, REALLY steep hills; side slopes would only feel the effect of the water slopping 90-100mm sideways... But you'd still have the problem of the static weight up that high!! Still, I'd guess the most convenient place to you for pipes like that would be along the sides of the roof rack, whereas the best place for vehicle stability for pipes like that would be along the centreline of the vehicle or roof rack, which would be a pain; but preferably along the centreline down as low as you can get them would be best... Not an easy thing to resolve!! :purplex:

Have you considered using bladder type water tanks in the rear seat footwells? We did that often, & even with our kids in the back - the bladders went under the rear seats & forwards into the footwell, or right across the car entirely in the footwell (we felt the free surface effect then, even down that low!); so the kids did lose a few inches of depth in there (but they enjoyed the soft & spongy feel under their feet!) but it got the weight of all our water down low & between the axles. We often carried 2 x 70 litre bladders down there, one each side, & sometimes augmented them with as many used 4l or 20l placcy wine cask type bladders we stashed anywhere they'd fit around the car/contents (they make great pillows & cushions when wrapped in a towel) & a couple of jerries of water in the back for the longer trips.

Or you could look into the placcy tanks that fit on top of Aux & Long Range fuel tanks (expensive tho); or maybe the heavy duty custom fit bladders for water or fuel that can fit inside the 1/4 panels or door skins (not cheap, but not quite as expensive) There's actually a LOT of un-used or poorly utilised space in 'modern' cars that isn't so obvious unless you really start taking trim panels etc off & looking into the cavities they cover!!

But you do need to be very aware of how much all this stuff can weigh & how loaded or over-loaded it'll make your vehicle plus what impact that load will have on your suspension & fuel economy etc - it's easy to overload most modern cars & wagons, even utes & dual cab utes!! Most cars & wagons (inc your 80) only have about 400kg payloads (& that includes the fuel load & the people sitting inside them too) while few utes & d/c utes have much more than a couple of hundred kgs extra at best!! And few have the capacity or construction to handle over-loading them by too much before you are likely to start breaking things if you ever go off-road or work them hard!! :(

All food for thought, isn't it?!? Sorry I can't be more directly helpful... ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

ridgey
Here and there
Posts: 22
Joined: July 22nd, 2009, 11:16 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by ridgey » April 5th, 2017, 9:14 pm

yes all very good food for thought! while this task is specifically for the cape trip coming up, generally speaking i would empty the tanks which would negate any slopping around of water.

So i looked up the effect you speak about above, my calcs and correct me if im wrong, 3 x 1.1m of pvc pipe would give me a total volume of about 26litres. the effect is at its worst when the water tank is at 50% correct? so that would be about 4 litres per tank, in total that would be about 12kg of weight, and only 4kg per tank

Those numbers seem pretty low in the scheme of things, less than my 3yr old being a little ***** and jumping around the back seat side to side. This little volume of water the effect would be negligible wouldnt it? i would understand if i had 200 litres slopping around

typhoeus
Need to get out more
Posts: 2058
Joined: February 6th, 2011, 8:25 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by typhoeus » April 5th, 2017, 9:53 pm

If you can make the pipe tanks with baffles inside, with small holes that allow the water to drain thru slowly, you ight be able to minimise the effects even further

ridgey
Here and there
Posts: 22
Joined: July 22nd, 2009, 11:16 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by ridgey » April 5th, 2017, 11:12 pm

ok i see, just a piece in the middle with holes in it

Peter Aawen
Admin
Posts: 20778
Joined: June 17th, 2005, 8:01 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by Peter Aawen » April 6th, 2017, 12:18 am

ridgey wrote:...my calcs and correct me if im wrong, 3 x 1.1m of pvc pipe would give me a total volume of about 26litres. the effect is at its worst when the water tank is at 50% correct? so that would be about 4 litres per tank, in total that would be about 12kg of weight, and only 4kg per tank....
I think you missed or incorrectly applied one of the big factors in the impact this has on your stability, & I can't remember what they call it/how to apply it (cos it was a loooong while ago now that I had to know all this stuff!) but IIRC when you reduce the 'tanks' from full there's a spot in the calcs where instead of 'dividing' to reflect the reduction in weight like everyone expects you to need to do, you actually hafta multiply by whatever that factor is cos the greater weight/volume full has less impact than the lesser weight/volume of a partially filled tank that lets its contents slosh around, if that makes any sense to you!! IIRC 1/2 filled tanks weighing say 12kgs will have (more than?) twice the FSeffect on your stability than full tanks weighing 24kgs do, cos of the movement & slosh dynamics that apply - and that's compounded by being up high, well above your vehicle's CoG so it has an even greater leverage effect on stability than your heavier kid bouncing around on the back seat closer to the CoG... the leverage increases exponentially as the height above CoG increases..... :purplex:

Honestly, I can't properly recall these formulae & even if I looked 'em up my brain's really not up for this sorta stuff anymore, especially at this time of night, but maybe some of the more recently knowledgeable readers can help?!? :confused:

Oh, & baffles can sometimes help reduce the effect a little, but unless they are designed properly for the purpose/application, they may also create a 'delayed slosh' that can make the FSeffect far worse - in some cases this has caused the capsize of otherwise eminently stable vessels, & may also be implicit in some vehicle roll-overs.... :o

But what all this really boils down to is:

1) be very wary of putting any excess weight up high on your vehicle;
2) if you do hafta put fluids up high/on your roof rack, put the fluids in smallish containers/tanks that are completely full & packed close to the centreline of the vehicle, not stretching across the width of the vehicle; &
3) when you need to use aforesaid fluids, empty the containers/tanks completely rather than leaving any up there partially full! :thumb:
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

mydmax
Need to get out more
Posts: 5384
Joined: August 4th, 2011, 10:43 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by mydmax » April 6th, 2017, 4:40 pm

If everyone on a properly loaded ferry suddenly run to one side the ferry will list alarmingly. Some run from the middle, some are already there, while others run fully cross deck. So, a sort of spread inertia.
If all are one one side, ie, like water in a tank with no baffles, then ALL the free water can be at one side and it's inertia built up from cornering, is suddenly forced against the outer side of the turn.
On ferries it turns them over, similar with landcruisers I would imagine.
If you hit a bump with the inside wheel at the same time it will require some fancy steering.

No manufacturers make water tanks for roof racks to my knowledge, Yes you can have one but is it wise?

V Williamson
Part of the furniture
Posts: 1388
Joined: February 6th, 2008, 9:16 am

Re: Got pics of your PVC pipe water tanks?

Unread post by V Williamson » April 6th, 2017, 5:28 pm

mydmax wrote:If everyone on a properly loaded ferry suddenly run to one side the ferry will list alarmingly...

On ferries it turns them over, similar with landcruisers I would imagine.
.....
No manufacturers make water tanks for roof racks to my knowledge, Yes you can have one but is it wise?
Just a bit of slightly off-topic history, read the 3rd paragraph in the link concerning the "Rodney" on Sydney harbour in 1938. https://en.wikipedia.org/wiki/Rosman_Ferries

I think the lateral watertank idea should be scratched myself considering the other posts. Ummm... if the intended trip is Cape York (correct me otherwise), do you really need remote desert like water capacity? I don't recall having a huge water supply on that trip, and we never ran dry. I am sure that even a day or three on the old telegraph track would have water that could be boiled at the least. Also if the Cape is the intended trip, beware of the corrugations and their effect on any fitting. The party next to us at the seisa campground (near the tip) lost their roofrack system entirely - it broke off! A load of sloshing water up that neck of the woods would add to the strain.

cmar
Avid Poster
Posts: 946
Joined: December 28th, 2010, 11:09 pm

Re: Got pics of your PVC pipe water tanks?

Unread post by cmar » April 8th, 2017, 11:28 am

Just remember apart from the sloshing effect as outlined above, just the static load will increase dramatically once you start moving.
For example the momentum equation is mass x velocity.
Therefore your 20Kg of water at even 5Km/hour has an effective static mass of 100 Kg, imagine what a sudden stop, ie hitting a washout or even say the stop at the bottom of Gunshot, is now tugging at your roof rack at something like the roof maximum load, irrespective of anything else you have put up there. I hope your rack is a sturdy steel one.

PVC pipe tanks belong under the vehicle, or maybe in the case of a ute in the tub or tray.
Haven't owned a 2WD since 1982.

Return to “Anything to do with 4WD's &/or related to Fourby's”