Evans waterless coolant

[revilla]

Afraid I'm with JK and JV. If somebody could prove an advantage I might change my mind. In the meantime I can only agree with Mark and Simon - in that I can say exactly the same about my G30!

[Jonathan Kay]

Toxicology

Wikipedia:

• Ethylene glycol poisoning
• Fomepizole

​Not much to add to those, and the discussion above.

The alcohol dehydrogenase inhibitor that's mentioned in the safety data sheet is very likely to be fomepizole. There are probably others but I don't know of any that have been studied in humans (apart from ethanol). It's possible that propylene glycol acts as a competitive inhibitor but I can't find anything about that.

It isn't possible to tell if the amount they add would be clinically useful unless anyone can come up with the concentration.​

The other thing that interests me is the inclusion of the ADH enzyme blocker.  I've always understood that these were prescribed after someone had drunk EG (or methanol, for that matter), rather than as a protective agent prior to drinking the stuff.

That is how it is used clinically but I'd expect it to be more effective if ingested with the toxin. (A similar approach was tried with paracetamol and methionine.)

Jonathan

1 The only bit I disagree with in the poisoning article is the mechanism of acidosis.

2 I've been teaching first year clinical medical students about this in the last few weeks, and nearly picked it as a topic for the prize vivas. They're not going to see much of it but it's a good idea to treat it right the first time they do. Very few NHS laboratories can measure either ethylene glycol or methanol in house, and very few EDs have a toxicologist on site. Apart from that it's a fascinating mechanism of disease and a convenient way to introduce the concepts of osmolal gap and anion gap.

3 It's an interesting regulatory problem. I'd guess that it hasn't gone through the processes for either a drug or a food, and it isn't being medically prescribed. This feels like a loophole.

4 I first heard about fomepizole in an episode of ER, and thought it was fictional. But they wouldn't count it when I submitted that for an hour's credit in my Continuing Professional Development.

[John Vine]

Well, thank you, Jonathan, for your erudite contribution.  Fascinating!

It's possible that propylene glycol acts as a competitive inhibitor but I can't find anything about that.

In 2001, an Evans patent application claimed that a level of PG (ditto glycerol) as low as 1% acts as an ADH enzyme inhibitor, sufficient to render EG non-toxic.  Apparently, the inventors (Messrs Evans and Light) were as surprised as anyone about this discovery:

"The results of the toxicity tests of the EG and PG mixtures were as astounding as they were unexpected. While the inventors do not wish to rely on or be limited to any particular theory as to why the addition of PG to EG results in an unexpectedly low oral toxicity for the mixture, the inventors believe that the PG acts as an ADH enzyme inhibitor. By incorporating PG into an EG formulation, the conversion of EG into glycoaldehyde is apparently significantly reduced or prevented altogether from the time of ingestion. Without the formation of glycoaldehyde, the further toxic metabolites of glycolic acid, glyoxylic acid, and oxalic acid are not created. Acidosis, precipitation of calcium oxylate crystals, hypocalcemia, renal failure, and all the other characteristics of EG poisoning do not occur. The inhibition provided by the PG remains until the EG is expelled from the body.

The significance of the discovery that even small amounts of PG mixed with EG render the mixture non-hazardous is that much larger percentages of EG than heretofore thought prudent can be incorporated into PG and EG coolant concentrates and the resulting mixture will be essentially non-toxic."

 

As far as I can tell, the application was rejected and later withdrawn.   I guess that's why Evans now employ a separate ADH blocker.

JV

[Jonathan Kay]

I didn't know about that. I was only speculating from enzymatic first principles: anything that nearly fits the active site might have that effect.

Jonathan

[John Vine]

Learning mode on....

Could you explain how (that is, which bit of) the EG molecule fits the ADH active site?  And would it be the same for PG?  And what about ethanol, for which, I believe, ADH has a much higher affinity? 

Re the patent rejection/withdrawal, what isn't clear is whether it was rejected because there was no new "inventive step" in the EG-PG formulation to differentiate it from existing formulations, or whether the reduced-toxicity claim was groundless, or both.

JV

[Jonathan Kay]

Could you explain how (that is, which bit of) the EG molecule fits the ADH active site?  And would it be the same for PG?  And what about ethanol, for which, I believe, ADH has a much higher affinity? 

Sorry, a man's got to know his limitations. The Wikipedia article on alcohol dehydrogenase(s) looks good, and there's probably a graphic somewhere....

Only one general thought to add: the difference between ethylene glycol and propylene glycol doesn't produce very different chemical properties, but enzymes are designed to be sensitive to shape and size. There are a couple of fascinating clinical examples:

Pseudocholinesterase deficiency, which probably affects at least one Member although he probably doesn't know. This can produce what's supposed to be one of the most terrifying experiences: consciousness with muscle blockade. And it's familial, so great for thrillers.

Medium-chain acyl dehydrogenase deficiency. Probably the only population screening programme for a condition which most doctors have never heard of, let alone seen. But there'll be more along soon...

Jonathan

[Jonathan Kay]

And some seasonal toxicology from The Guardian: "New Year's Eve partygoers told to beware of fake booze".

Jonathan

[John Vine]

Thanks, Jonathan.  Plenty of light reading material there!

And Harry Callahan is right.

JV

[Jonathan Kay]

Here you are, Derek. I suggest reading the whole thing from the beginning.

Jonathan

[anthonym]

These me too/me not exchanges have set me reflecting. I use EW in my year2001 Mondeo, after a water pump housing failure. Installation is a different discussion. It’s a test before Seven, a year 2000 R500K, which is on it’s second refresh threshold of 48,000 miles: determined not required yet based on compression test results and ant running very well. It’s not broken so not fixing it. When it is eventually dismantled I will be looking for any evidence of corrosion caused by water based coolant, and do hotspots  create any evidence?

(1) availability of EW for top up will always be an issue. Granted I have never used even the one litre of spare G13 I carry. Mondeo needed a top up, to my surprise recently: curious why. 

(2) upon release of hot expansion tank cap, almost (not quite) zero pressure release. A non pressurised system has an attraction to me, less coolant loss for a given failure. Though maybe harder to find the leak

(3) Mondeo runs a tiny bit hotter per the temp guage. Seems harmless, arguably more power. 

(4) It’s expensive. Thus requires careful guardianship, which is at the least nuisance value. 

(5) Demands careful conversation with any garage etc NOT to dump a same colour anti freeze in it. AND to cleanly collect and reuse. Risk of « customers know nothing » approach. Including Ford ( cost me double purchase of EW).

(6) A special measurement tool NOT SUPPLIED has to be discovered and acquired to test the final install. Found deep in the instructions. 

(7) A saucerful with a lit match dropped in and left eventually catches fire. 

Jury remains out concerning whether it will go into my Seven: availability and fire being my two interests.

Anthony

[Jonathan Kay]

(3) Mondeo runs a tiny bit hotter per the temp guage.

That's explicable from the known physical properties. And the suppliers suggest "3 - 10ºC hotter than those using water-based coolants".

... arguably more power. 

In 2015 the suppliers withdrew claims for greater power output after their advertisements were referred to the ASA.

Jonathan

[anthonym]

I'm not repeating their claims.

I'm observing that more heat means more power. not that I can discern any difference... maybe I should check the fuel economy.. but I'd have to remove the brick tied to the accelerator...

I think of most interest to my Seven is the claim about preventing hotspots in the K engine, but after 15 years or so it seems a academic.

I suppose also there is a sort of attraction to the idea of not putting water in to a metal engine...

[Jonathan Kay]

I'm observing that more heat means more power.

Why?

My mental model of this is that the combustion/ power output/ thermal efficiency of the heat engine aren't significantly affected. But the lower thermal capacity of the Evans waterless coolant means that the cooling system has to be hotter for the same thermal transfer. 

Are you thinking of the higher theoretical thermodynamic efficiency of the heat engine because of higher peak temperature?

Jonathan

[anthonym]

not really. :-)

however... yes probably. hotter coolant is hotter engine, seems to me. But really, it's not a reason to use or not use it.

have I got to go look up the laws of thermodynamics? I will if it's important..

"In the process of energy transfer, some energy will dissipate as heat." is that your premise? The extra heat is simply dissipated?

I suspect an answer to that would be some is, some isn't depending which direction the heat goes. But I'm thinking coolant temp is measuring the temp of the whole engine, and so some of it ends up in assisting combustion. not that I had thought this far!

[Jonathan Kay]

Thanks.

have I got to go look up the laws of thermodynamics? I will if it's important..

Not in my view of what's happening. But admirable devotion to the cause. :-)

"In the process of energy transfer, some energy will dissipate as heat." is that your premise? The extra heat is simply dissipated?

Not really. I think that the same amount of heat is generated and has to go somewhere. As the thermal capacity of the coolant is lower AND the bulk flow of coolant is the same (!) AND the final transfer from the coolant is to air at the same temperature and flow etc THEN all the intermediate points between the source of the heat and the transfer to air must be hotter.

Jonathan 

[anthonym]

hmm, I think I tend to disagree in so far as the element beng "cooled" (the engine block), is surrounded by a warmer "blanket" i.e. coolant jacket, so rather than the block being at the same temperature as previously, seems to me it will be warmer by virtue of its wearing a warmer jacket. i.e. we can't have a block relatively cooler than the jacket by a difference of any more that it was previously. 

I don't know how many degrees my Mondeo is warmer by as its an analogue guage. About 2 mm more to the right.  Which can't be much.

it (the block) gets hotter before it's (the heat) disspiated..

[Jonathan Kay]

I don't think that we're disagreeing... the block is one of the intermediate points between the generation of heat and its transfer to the air that must be hotter...

Jonathan 

[anthonym]

"..the generation of heat.." you mean the combustion itself? ok so that begs the question from where comes the idea that greater heat means more energy (power) in the context of the combustion engine.. in any case a couple of degrees isn't relevant (I imagine) in the context of combustion (ignition of the fuel). Methinks I am missing something..

[Jonathan Kay]

"..the generation of heat.." you mean the combustion itself?

Yes. (Other sources such as friction being unaffected.)

ok so that begs the question from where comes the idea that greater heat means more energy (power) in the context of the combustion engine..

That's what I was asking in #113. Who is saying that it does? (My contention is that the generation of heat is unchanged but the cooling system runs hotter because the thermal capacity of the coolant is lower.)

in any case a couple of degrees isn't relevant (I imagine) in the context of combustion (ignition of the fuel).

Agreed.

Jonathan

 

[anthonym]

hmm.. just seems to be a common idea down the years from various engineers.. I'll have to reflect a bit where it comes from.. but the idea is more heat means more power.

.. doubtless someone will be along momentarily..

edit: finding this an interesting read http://www.enginebuildermag.com/2017/06/tempering-horsepower-heat-keeping-cool-heat-handling-accessories/

Well, that is a very interesting read. 

[Jonathan Kay]

Con: Expensive and not easy to top up if you haven't got extra with you.

Pro: Lower pressure, hence not the same need for a huge expansion bottle which is good when space is at a premium.

(and smaller bottle, less coolant=lighter)

Does the lower pressure within the system allow the use of a smaller expansion bottle? Assuming that neither is boiling wouldn't that depend on the bulk expansion rather than the pressure?

Jonathan

[rj]

If the pressure is lower at the same volume / temperature, then I think there'd be less need for "room for expansion" without having a critical pressure.

 

[Jonathan Kay]

Haven't found the 996 story but here's a 968, Ian.

Jonathan

[Jonathan Kay]

If the pressure is lower at the same volume / temperature, then I think there'd be less need for "room for expansion" without having a critical pressure.

The expansion will depend on the temperature change and the coefficient of bulk expansion (and the volume). The first will be higher and I don't know the second.

Other things being equal an engine cooled by Evans Waterless Coolant will be hotter than an engine cooled by water and ethylene glycol. The vendors say "3 to 10°C".

We don't know that the pressure of the coolant is different between the two coolants. The pressure in the head space above is, and that's what people notice when they remove the cap.

Jonathan

[rj]

If the pressure is lower I assume the heat expansion is less.

However, reading through the thread I'm not sure I wan't something that can catch fire above my primaries and in the crash deformation zone (called a radiator) of my car.