Diesel tank filter gone green

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Graham_Wright

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I machined up a coarse filter for immersion in the diesel tank and very professional it looked too.

On fishing it out last night during some mods, I found it had acquired a green coating. This was quite thick and scraped off by finger easily.

What might it be, is it a concern and what should I do about it?

The material is CZ121 (brass) and I could have it plated with zinc or nickel if necessary.

As many of the other fittings in fuel system are brass, should I worry?
 
nigelmercier said:
Doesn't this just mean it is doing its job, and filtering out the diesel bug?
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The filter assembly is a solid brass ring with a gauze insert retained by a perforated SS (316) disc.

The gunge is on the periphery of the ring. The gauge is clear and so is the solid top of the assembly!

There is no water in the tank but it was filthy (still in commissioning mode) and I vacuumed out all the contents.

I am a debutant when it comes to diesel bug.
 
I don't know about the green colour, but diesel reacts differently with different metals. We have a fibreglass tank which is as clean as can be considering its age, but the old copper dip pipe has accumulated a thick crust of black deposit over the years both inside and out which has eaten into the copper. I struggle to accept that it's bug when the rest of the tank is so clean and have therefore assumed it is a long term reaction with copper, possibly exacerbated by the Soltron or Grotamar additive that we've been using.
 
I have found these two statements on a mechanic's forum.

"Diesel's harmless to brass and vice-versa. "

"BioDiesel and copper are absolutely incompatible. Depending on the exact alloy, that may also be true of brasses and bronzes - especially the less-expensive ones found at the local hardware store."

I'm really no wiser.

Where's Vic - he's the expert on things chemical.
 
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Rogershaw said:
Your post #6 You quoted from a mechanic's forum.

"BioDiesel and copper are absolutely incompatible. Depending on the exact alloy"
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There is a full stop! Read it again - slowly!

"BioDiesel and copper are absolutely incompatible. Depending on the exact alloy, that may also be true of brasses and bronzes - especially the less-expensive ones found at the local hardware store."
 
I read my highlighted comment to refer to their comment about copper. Yes Brass and bronze are alloys and do have different proprieties.

Like you I have no idea what sent your brass fitting green and like you would like to know. The only colour I have seen brass, bronze or copper go is black due to oxidation in the marine environment.

Hope you get an answer.
 
Rogershaw said:
I read my highlighted comment to refer to their comment about copper. Yes Brass and bronze are alloys and do have different proprieties.

Like you I have no idea what sent your brass fitting green and like you would like to know. The only colour I have seen brass, bronze or copper go is black due to oxidation in the marine environment.

Hope you get an answer.
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That answer I was hoping would be sourced by VicS.

Vic! Vic!Vic!Vic!Vic!

Vic!
 
I am intrigued and also await Vics response, in the mean time I think you could have created arsenic and suggest you dont run a taste test .

Electrolysis between the stainless gauze through the diesel to the copper= home made arsenic :eek:

could be a load of old cobblers but seem to recall years ago people died in their bedrooms wallpapered died with blue derived from copper which created arsenic in the right conditions.
 
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DAKA said:
I am intrigued and also await Vics response, in the mean time I think you could have created arsenic and suggest you dont run a taste test .

Electrolysis between the stainless gauze through the diesel to the copper= home made arsenic :eek:

could be a load of old cobblers but seem to recall years ago people died in their bedrooms wallpapered died with blue derived from copper which created arsenic in the right conditions.
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Ooer! Nasty. The gauze is brass but the securing disc is 316 SS.

Vic!
 
DAKA said:
I am intrigued and also await Vics response, in the mean time I think you could have created arsenic and suggest you dont run a taste test .

Electrolysis between the stainless gauze through the diesel to the copper= home made arsenic :eek:

could be a load of old cobblers but seem to recall years ago people died in their bedrooms wallpapered died with blue derived from copper which created arsenic in the right conditions.
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Creating arsenic (an element) from copper (another element) ? That's as likely as achieving the old Alchemist dream of converting base metals into gold !

As to the green colour, some copper salts are green.
.
 
GrahamHR said:
Creating arsenic (an element) from copper (another element) ? That's as likely as achieving the old Alchemist dream of converting base metals into gold !

As to the green colour, some copper salts are green.
.
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Accepted , apologies to the op for misdirection, feel free to proceed with taste test :D.


Which great military leader died from poison while laid in their bed from wall paper poisoning from blue dye made from copper ? Napoleon ?
 
No idea.

Nothing I'd think to do with arsenic. CZ121 does not, AFAIK, contain arsenic although Admiralty brass contains a very small amount.

Wikipedia will tell you all about Scheele's green once used as a green pigment and even as a food colourant :eek:

I'd think the green colour was due to the formation of a hydrated copper compound but that would imply the presence of water, although not necessarily as free liquid.

Biodiesel might be the cause of the trouble see Wikipedia's entry on biodiesel but Ive no idea what the green matter is. ... I'd have sent that to the Analytical Chemists to identify !

If this green is appearing on the brass adjacent to its junction with the stainless steel it implies some sort of "dissimilar metal" effect.
 
DAKA said:
Accepted , apologies to the op for misdirection, feel free to proceed with taste test :D.


Which great military leader died from poison while laid in their bed from wall paper poisoning from blue dye made from copper ? Napoleon ?
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From Google;-

Scheele's Green was a colouring pigment that had been used in fabrics and wallpapers from about 1770. It was named after the Swedish chemist Scheele who invented it. The pigment was easy to make and was a bright green colour but under certain circumstances the copper arsenite could be deadly. Gosio discovered that if wallpaper containing Scheele's Green became damp and then became mouldy, the mould could carry out a chemical process to get rid of the copper arsenite. It converted it to a vapour form of arsenic, normally a mixture of arsine, dimethyl and trimethyl arsine which was very poisonous. If Napoleon's wallpaper had been green, it could possibly have contained arsenic, and this could have been the source of the arsenic in the hair sample. Napoleon might have been an early victim of Gosio's disease.
 
VicS said:
No idea.

Nothing I'd think to do with arsenic. CZ121 does not, AFAIK, contain arsenic although Admiralty brass contains a very small amount.

Wikipedia will tell you all about Scheele's green once used as a green pigment and even as a food colourant :eek:

I'd think the green colour was due to the formation of a hydrated copper compound but that would imply the presence of water, although not necessarily as free liquid.

Biodiesel might be the cause of the trouble see Wikipedia's entry on biodiesel but Ive no idea what the green matter is. ... I'd have sent that to the Analytical Chemists to identify !

If this green is appearing on the brass adjacent to its junction with the stainless steel it implies some sort of "dissimilar metal" effect.
Click to expand...

Thanks Vic. I'll report or get the wife to report on the results of the taste test.:cool:
 
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