[dave14]

Need some advice regarding titanium tube cooling as Have upgraded to 2 x 400w

I know Simon (reefyman ) has done one. I know the basics but would a 3mtr coil (150mm coil dia) 8mm tube be sufficient and also is any grade Titanium ok to use?

Thanks

[chriss]

Ah yes, titanium tubing, got some of that if you want, didn't I already offer it to you, sorry forgot all about it!

There are all different alloys, pure ti is not suitable, generally aluminium is alloyed in along with small quantities of other metals, there is no problem with this leaching out if you have a high enough quality tube, which I have! I haven't got the tech specs here, it's at work I'll post it up tomorrow.

What Simon had off me was a load of short lengths around 20 inches or so, these were all joined up using t-pieces and hose to form a kind of radiator which he then put in his sump and plumbed into the tap. I was planning on doing the same thing, but haven't found it necessary as yet.

Of course, you can buy purpose built titanium heat exchangers, but they cost a pretty penny.

I'll dig the tubing out, photo/measure what I've got and let you know.

Ah, you know where it is don't you...it's in my garage...somewhere in the back of the garage behind the jacuzzi! Fortunately there is a door at that end so I should be able to reach it, leave it with me.

Chris

[dave14]

Thanks Chris, no rush any time tomorrow will do

[reefyman]

hi dave
yea im probably going to make mine a bit bigger using the rest of the lengths of tubing that i got off chriss to go in my new sump/frag system,only used half of them so far.did a bit of research on the titanium and apparently the titanium oxidises instantly on contact with the air and so creates a inert barrier.on my system im using mains pressure and because the pipe is small bore you need to keep the overall length short ie the longer the pipe at this small bore the slower the flow.theres probably an ideal flow to bore rate to maximise the cooling effienciency but this works for me.
simon

[dave14]

Simon what is the total length that you have used and what dia tube is it?

Do you think the 3 mtr ready made coil at 8mm dia would do as I can get it for £30

[chriss]

dave14, on Mar 31 2009, 11:53 PM, said:

Simon what is the total length that you have used and what dia tube is it?

Do you think the 3 mtr ready made coil at 8mm dia would do as I can get it for £30

Thats a bargain! My tube, off-cuts from aerospace brake lines, cost over £100, admittedly there is quite a bit more than 3 meters.

The tube I have, and simon, is something like 9.5mm OD and is "Ti 3Al2-5V Grade 9"

I think I have the ones in the box in the photo, thats 20 16 inch lengths, I'll dig them out this evening and let you know

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Here is the blurb about Ti corrosion from the manuacture of the tubes I have, 'Finetubes'....



Corrosion of Titanium and Titanium Alloys
Abstract:
Titanium alloys were originally developed in the early 1950s for aerospace applications, in which their high strength-to-density ratios were especially attractive. Although titanium alloys are still vital to the aerospace industry for these properties, recognition of the excellent resistance of titanium to many highly corrosive environments, particularly oxidizing and chloride-containing process streams, has led to widespread non-aerospace (industrial) applications

Titanium alloys were originally developed in the early 1950s for aerospace applications, in which their high strength-to-density ratios were especially attractive. Although titanium alloys are still vital to the aerospace industry for these properties, recognition of the excellent resistance of titanium to many highly corrosive environments, particularly oxidizing and chloride-containing process streams, has led to widespread non-aerospace (industrial) applications.

Because of decreasing cost and the increasing availability of titanium alloy products, many titanium alloys have become standard engineering materials for a host of common industrial applications. In fact, a growing trend involves the use of high-strength aerospace-founded titanium alloys for industrial service in which the combination of strength to density and corrosion resistance properties is critical and desirable.

The excellent corrosion resistance of titanium alloys results from the formation of very stable, continuous, highly adherent, and protective oxide films on metal surfaces. Because titanium metal is highly reactive and has an extremely high affinity for oxygen, these beneficial surface oxide films form spontaneously and instantly when fresh metal surfaces are exposed to air and/or moisture. In fact, a damaged oxide film can generally reheal itself instantaneously if at least traces of oxygen or water are present in the environment. However, anhydrous conditions in the absence of a source of oxygen may result in titanium corrosion, because the protective film may not be regenerated if damaged.

The nature, composition, and thickness of the protective surface oxides that form on titanium alloys depend on environmental conditions. In most aqueous environments, the oxide is typically TiO2, but may consist of mixtures of other titanium oxides, including TiO2, Ti2O3, and TiO. High-temperature oxidation tends to promote the formation of the chemically resistant, highly crystalline form of TiO, known as rutile, whereas lower temperatures often generate the more amorphous form of TiO, anatase, or a mixture of rutile and anatase.
Although these naturally formed films are typically less than 10 nm thick and are invisible to the eye, the TiO; oxide is highly chemically resistant and is attacked by very few substances, including hot, concentrated HCl, H2SO4, NaOH, and (most notably) HF. This thin surface oxide is also a highly effective barrier to hydrogen.

The methods of expanding the corrosion resistance of titanium into reducing environments include:
• Increasing the surface oxide film thickness by anodizing or thermal oxidation
• Anodically polarizing the alloy (anodic protection) by impressed anodic current or galvanic coupling with a more noble metal in order to maintain the surface oxide film
• Applying precious metal (or certain metal oxides) surface coatings
• Alloying titanium with certain elements
• Adding oxidizing species (inhibitors) to the reducing environment to permit oxide film stabilization

Titanium alloys, like other metals, are subject to corrosion in certain environments. The primary forms of corrosion that have been observed on these alloys include general corrosion, crevice corrosion, anodic pitting, hydrogen damage, and SCC.
In any contemplated application of titanium, its susceptibility to degradation by any of these forms of corrosion should be considered. In order to understand the advantages and limitations of titanium alloys, each of these forms of corrosion will be explained. Although they are not common limitations to titanium alloy performance, galvanic corrosion, corrosion fatigue, and erosion-corrosion are included in the interest of completeness.


General corrosion is characterized by a relatively uniform attack over the exposed surface of the metal. At times, general corrosion in aqueous media may take the form of mottled, severely roughened metal surfaces that resemble localized attack. This often results from variations in the corrosion rates of localized surface patches due to localized masking of metal surfaces by process scales, corrosion products, or gas bubbles; such localized masking can prevent true uniform surface attack.
Titanium alloys may be subject to localized attack in tight crevices exposed to hot (>70 oC) chloride, bromide, iodide, fluoride, or sulfate-containing solutions. Crevices can stem from adhering process stream deposits or scales, metal-to-metal joints (for example, poor weld joint design or tube-to-tubesheet joints), and gasket-to-metal flange and other seal joints.

Pitting is defined as localized corrosion attack occurring on openly exposed metal surfaces in the absence of any apparent crevices. This pitting occurs when the potential of the metal exceeds the anodic breakdown potential of the metal oxide film in a given environment. When the anodic breakdown potential of the metal is equal to or less than the corrosion potential under a given set of conditions, spontaneous pitting can be expected.

Titanium alloys are widely used in hydrogen containing environments and under conditions in which galvanic couples or cathodic charging causes hydrogen to be evolved on metal surfaces. Although excellent performance is revealed for these alloys in most cases, hydrogen embrittlement has been observed.
The surface oxide film of titanium is a highly effective barrier to hydrogen penetration. Traces of moisture or oxygen in hydrogen-containing environments very effectively maintain this protective film, thus avoiding or limiting hydrogen uptake. On the other hand, anhydrous hydrogen gas atmospheres may lead to absorption, particularly as temperatures and pressures increase.

Stress-corrosion cracking (SCC) is a fracture, or cracking, phenomenon caused by the combined action of tensile stress, a susceptible alloy, and a corrosive environment. The metal normally shows no evidence of general corrosion attack, although slight localized attack in the form of pitting may be visible. Usually, only specific combinations of metallurgical and environmental conditions cause SCC. This is important because it is often possible to eliminate or reduce SCC sensitivity by modifying either the metallurgical characteristics of the metal or the makeup of the environment.
Another important characteristic of SCC is the requirement that tensile stress is present. These stresses may be provided by cold work, residual stresses from fabrication, or externally applied loads.
The key to understanding SCC of titanium alloys is the observation that no apparent corrosion, either uniform or localized, usually precedes the cracking process. As a result, it can sometimes be difficult to initiate cracking in laboratory tests by using conventional test techniques.

Chris

[Crabbit]

reefyman, on Mar 31 2009, 11:45 PM, said:

hi dave
yea im probably going to make mine a bit bigger using the rest of the lengths of tubing that i got off chriss to go in my new sump/frag system,only used half of them so far.did a bit of research on the titanium and apparently the titanium oxidises instantly on contact with the air and so creates a inert barrier.on my system im using mains pressure and because the pipe is small bore you need to keep the overall length short ie the longer the pipe at this small bore the slower the flow.theres probably an ideal flow to bore rate to maximise the cooling effienciency but this works for me.
simon

How did you joint the bits together? Did you get them tig welded?

[SLAPPY]

Crabbit, on Apr 1 2009, 10:58 AM, said:

How did you joint the bits together? Did you get them tig welded?

I'm sure a re-inforced hose on marine grade stainless should be ok.

[chriss]

Hi Dave,

I dug out the bits of tube, and there are ten pieces all around 16.5 inches long....

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Simon just used a good push fit hose. I planned on doing something slightly different by taking some small vdl hose tails, drilling them out to 9mm and then gluing them on using a thick cyano. I did a couple pieces as a trial which seemed to remain intact but never got round to finishing it off.

Chris

[Crabbit]

SLAPPY, on Apr 1 2009, 06:20 PM, said:

I'm sure a re-inforced hose on marine grade stainless should be ok.

Marine grade stainless will react with the iron in the water. Its not as good as its made out to be. A small amount of iron contamination with oxidize the alloy.

[reefyman]

dave
youre welcome round my place any time if you want to see mine in action(oh err that sounds a bit rude)

[dave14]

reefyman, on Apr 2 2009, 09:39 PM, said:

dave
youre welcome round my place any time if you want to see mine in action(oh err that sounds a bit rude)

Lol, thanks Simon will take you up on that, I did have a quick look when we were over last but would be good to have a closer look at how you made it up.

Cheers

[dave14]

Simon, is it still ok for me to pop over some time, with the weather warming up i need to sort something out.

Cheers Dave

[reefyman]

hi dave
yea sure no problem,ive got me new sump up and running now and the cooler is really easy to see and get to.i should be around most of the weekend if you want to pop in,shopping down at morrisons sat morn other than that should be here.ill pm my mob no if you need to get hold of me
cheers simon

[jason@jasonsaquatics]

Hi Simon

Have you got any pics of the done job

jas

[wayne sarah kernow]

Has anyone tried/thought of running a ground source cooling type system??

ground is between 11 and 13 degrees so just get enough pipe in the ground and pump it round and you will get at least some sort of cooling??

[chriss]

wayne sarah kernow, on May 21 2009, 05:35 PM, said:

Has anyone tried/thought of running a ground source cooling type system??

ground is between 11 and 13 degrees so just get enough pipe in the ground and pump it round and you will get at least some sort of cooling??

Unfortunately you've got to dig up your garden to fit it.

Chris

[jason@jasonsaquatics]

Underground cooling is a good idea and has been in use for a long time now .

Problem is most will struggle getting it past the wife/girlfriend running the pipework down the hallway to the front or back garden .

There is another way that Si G uses and thats pulling outside air into the skimmer through an oversize pipe .Also this will help with the display tanks Ph level ,but again most may find it hard to run that past the wife/girlfriend


Jas

[karnivor]

well, ive got 2 x 400w halides and 3 computer fans blowing on the surface. I never go above 79f or below 77f.
Cheap as chips, works a treat. It just costs me 1 watering can of water every 2 days.