Food dye to help identify a fresh water leak?

[Ian_Edwards]

I was wondering if I could use a food dye to find a water leak. The idea would be to add the dye to an almost empty water tank and then search under the floor with a torch.
Then flushing, the tank multiple times, in the same way as I do after disinfecting the tanks at the beginning of each season.
Any potential pitfalls in doing this?

 

[STOL71]

I was wondering if I could use a food dye to find a water leak. The idea would be to add the dye to an almost empty water tank and then search under the floor with a torch.
Then flushing, the tank multiple times, in the same way as I do after disinfecting the tanks at the beginning of each season.
Any potential pitfalls in doing this?

Best to check for leaks when the tank is full as there will then be higher pressure in the tank.

 

[Ludd]

Best to check for leaks when the tank is full as there will then be higher pressure in the tank.

Either way, you'll need a VERY HIGH percentage of dye before you'll be able to see it.

 

[MikeBz]

I don't know why you would need to flush the tank afterwards, once it's full the dye will be insignificant and of course harmless in any concentration.

A friend worked in a high position for an F1 team/engine builder in the 1990s/2000s. Considering the myriad of wonder coolant products and additives on the market touting improved cooling and elimination of overheating, guess what F1 engines use for coolant? Water - because it has a better specific heat capacity than anything else - with a dash of food colouring so it's easy to identify if there is a leak.

 

[VicS]

I was wondering if I could use a food dye to find a water leak. The idea would be to add the dye to an almost empty water tank and then search under the floor with a torch.
Then flushing, the tank multiple times, in the same way as I do after disinfecting the tanks at the beginning of each season.
Any potential pitfalls in doing this?

You will need a very strongly coloured dye ... Cochineal perhaps ???

Fluorescein ( sodium salt) and a UV light would be much more effective ( but make the water very slightly alkaline by the addition of a tiny amount of caustic soda or sodium carbonate if you are not in a hard water area )

 

[Ian_Edwards]

I had Cochineal in mind and had considered Fluorescein, but I thought Fluorescein was poisonous. The leak is quite slow, it only really shows as water in the bilge after a week or so.
The way the boat is constructed means that you can only access a small part of the inner surface of the hull and the pipework without removing lots of furniture and fittings.
I think in might have another go at tracing all the pipework and checking all the fittings again.

 

[Stemar]

If it's enough of a leak to matter - apart from making the pump burp occasionally - dry everything off and spread a light dusting of talc around. Come back the next day or the next couple of minutes depending on how bad it is, and see where the run marks are in the powder.

 

[prof pat pending]

If it's enough of a leak to matter - apart from making the pump burp occasionally - dry everything off and spread a light dusting of talc around. Come back the next day or the next couple of minutes depending on how bad it is, and see where the run marks are in the powder.

+1

Tried and tested method for finding water leaks

 

[fisherman]

It didn't take very much powder to turn my engine coolant bright fluorescent green, to differentiate from any sea water lying about, also red diesel.

 

[macd]

A friend worked in a high position for an F1 team/engine builder in the 1990s/2000s. Considering the myriad of wonder coolant products and additives on the market touting improved cooling and elimination of overheating, guess what F1 engines use for coolant? Water - because it has a better specific heat capacity than anything else - with a dash of food colouring so it's easy to identify if there is a leak.

There's also the not insignificant fact that antifreeze is very slippery and much harder than water to clean from the track. In many formulas/circuits, it's banned.
(At the Le Mans 24-hour bike race one year, we were ordered by scrutineers to remove our engine's antifreeze. It was snowing at the time...)

 

[AntarcticPilot]

I had Cochineal in mind and had considered Fluorescein, but I thought Fluorescein was poisonous. The leak is quite slow, it only really shows as water in the bilge after a week or so.
The way the boat is constructed means that you can only access a small part of the inner surface of the hull and the pipework without removing lots of furniture and fittings.
I think in might have another go at tracing all the pipework and checking all the fittings again.

Well, if fluorescein is poisonous, I ought to be dead! First, I used it routinely as an indicator in the school chemistry lab, and we used mouth operated pipettes in those days! My hands used to have yellow stains quite routinely. And second, it is routinely used by ophthalmologists when checking the fit of contact lenses. As there is a direct connection between the tear ducts and the mouth, a proportion of the fluorescein ends up in the mouth and nose, as evidenced on handkerchiefs afterwards!

 

[Stemar]

From somewhere on the web:
Fluorescein is not considered hazardous. Its toxicity is stated as LD50 oral in rats 6,721 mg/kg [6], which suggests that the lethal dose in 80kg humans is around 500g of the pure dye. (Compare the toxicity of ethanol, LD50 oral in rats 9,000 mg/kg, lethal dose in 80kg humans is around 720g.)

 

[Ian_Edwards]

OK, I now know that Fluorescein isn't toxic, so how much would I need to make say 50L of water visible in UV light?

I can buy 100g of Fluorescein on eBay and a UV torch, for not a lot of money.

https://www.ebay.co.uk/p/100g-fluor...ter-tracing/1324739373?_trksid=p2047675.l2644

http://www.ebay.co.uk/itm/Portable-...Flash-light-Black-light-Lamp-UK-/112361781539

All I'd need now is a guess at the concentration required.

Anyone out there who could provide that info' or a link to where I can find it?

 

[Hugh Foulis]

I used to use fluorescein dye for drain tracing many years ago, cannot give you an empirical formula but quarter of a teaspoon flushed through a WC was visible to the naked eye after it had travelled the length of a housing estate and another mile down the sewer. It does not need much.
As an aside I spent a very fruitless day using various colours of dye to nail a leak in a hotel plumbing system that was filling the cellar of the petshop next door. Called it a day after no success in seeing any of the colours appear anywhere so I walked back to the office. I must have been a little over enthusiastic with the green, because driving home about an hour later passed the hotel there was a large group of people all staring at a very bright green stain spreading extensively over the road and pavement. Naturally I just kept on driving.

 

[VicS]

OK, I now know that Fluorescein isn't toxic, so how much would I need to make say 50L of water visible in UV light?

I can buy 100g of Fluorescein on eBay and a UV torch, for not a lot of money.

https://www.ebay.co.uk/p/100g-fluor...ter-tracing/1324739373?_trksid=p2047675.l2644

http://www.ebay.co.uk/itm/Portable-...Flash-light-Black-light-Lamp-UK-/112361781539

All I'd need now is a guess at the concentration required.

Anyone out there who could provide that info' or a link to where I can find it?

You can buy the fluorescein from Toolstation conveniently and more cheaply:- http://www.toolstation.com/shop/p19855?table=no

It may be supplied the sodium salt as fluorescein itself is not very soluble in water.

You won't need very much for 50 l A gram at the most probably a lot less but don't ignore what I said about making the water very slightly alkaline ... It wont fluoresce if its acidic

 

[AntarcticPilot]

I used to use fluorescein dye for drain tracing many years ago, cannot give you an empirical formula but quarter of a teaspoon flushed through a WC was visible to the naked eye after it had travelled the length of a housing estate and another mile down the sewer. It does not need much.
As an aside I spent a very fruitless day using various colours of dye to nail a leak in a hotel plumbing system that was filling the cellar of the petshop next door. Called it a day after no success in seeing any of the colours appear anywhere so I walked back to the office. I must have been a little over enthusiastic with the green, because driving home about an hour later passed the hotel there was a large group of people all staring at a very bright green stain spreading extensively over the road and pavement. Naturally I just kept on driving.

Also, don't forget it is a dye, and permanently stains some surfaces. During my 6th form Chemistry years, my hands were stained yellow quite a lot of the time, and stayed that was until the skin surface renewed itself in the normal course of events!

 

[VicS]

Also, don't forget it is a dye, and permanently stains some surfaces. During my 6th form Chemistry years, my hands were stained yellow quite a lot of the time, and stayed that was until the skin surface renewed itself in the normal course of events!

I cant imagine what you used in for in 6th form chemistry. I am sure I didn't and similarly I am sure it was not used when I worked in a school chemistry department more recently.

The only thing I've used it for is leak detection ( or more accurately I've prepared the solution for the engineers on the night shift to use)

 

[AntarcticPilot]

I cant imagine what you used in for in 6th form chemistry. I am sure I didn't and similarly I am sure it was not used when I worked in a school chemistry department more recently.

The only thing I've used it for is leak detection ( or more accurately I've prepared the solution for the engineers on the night shift to use)

I certainly used it in some titrations; I actually can't recall what it was used as an indicator for! I did my A-levels back in the dark ages (1967-1970) and I know the curriculum has changed a great deal since then. I've just looked it up - it is used with silver nitrate to do quantitative analysis of chlorides. I did do post-A-level work for S-levels, so it may be that my recollection is of things beyond the normal curriculum.

 

[VicS]

I certainly used it in some titrations; I actually can't recall what it was used as an indicator for! I did my A-levels back in the dark ages (1967-1970) and I know the curriculum has changed a great deal since then. I've just looked it up - it is used with silver nitrate to do quantitative analysis of chlorides. I did do post-A-level work for S-levels, so it may be that my recollection is of things beyond the normal curriculum.

Surprised that came into A level but they did raise the bar considerably from what I have seen around the time you were taking yours. Later fell back to little more than what was previously O level standard once GCSEs came in. I reckon anyone passing A level when you did bloody well earned it.

The method is in my Analytical Chemistry text book but I've never even read up on it let alone used it! Pity I am retired with no lab access or I might have given it a whirl just for fun!

 

[AntarcticPilot]

Surprised that came into A level but they did raise the bar considerably from what I have seen around the time you were taking yours. Later fell back to little more than what was previously O level standard once GCSEs came in. I reckon anyone passing A level when you did bloody well earned it.

The method is in my Analytical Chemistry text book but I've never even read up on it let alone used it! Pity I am retired with no lab access or I might have given it a whirl just for fun!

When I did A-level, the pass mark was set at a defined proportion of the entrants - it wasn't a mark level; the mark level was set after the exam so that a set proportion passed and was assigned to each grade. It did have the advantage from the POV of an examinee that if it was a hard paper, you knew it was the same for everyone! Also, the curriculum was designed so that you had knowledge that would be useful in a laboratory; I could have left school and taken jobs in an analytical laboratory that would be the province of a graduate these days. S-level was a cherry on top of A-level; it was supposed to be the same curriculum as A-level, but requiring independent thought to be demonstrated.

I'm afraid I was known as the school swot in Chemistry and Physics - there were a couple of people better than me at Maths!