How much coolant concentrate is needed?

LeonUoS · Aug 4, 2020

Hi Everyone,

I'm a PhD student studying cryogenic cutting fluids, where, as part of my PhD i'm hoping to undertake a cost analysis of cryogenic coolants compared to typical metalworking fluid (specifically Blaser Vasco 7000).

I have recently come into the problem of calculating how much coolant concentrate would be needed to fill a 200L tank to 8% concentration. Intuitively, I had assumed that that would simply mean adding 16L of concentrate to 184L of water, however, upon asking a machinist colleague he informed me that due to the refractive index of the coolant (1.5), I would actually only need to use 5.3% (10.7L) of the coolant concentrate to achieve a true concentration of 8%.

This seems strange to me, I trust my colleague as he as a wealth of practical experience (of which I have almost none) however, surely the 'True' concentration would be the true proportion of the mixture which is oil (and in which case 8%), rather than the effective concentration of the oil when refractive index is accounted for?

If my colleague is correct, would this then be to say that the refractometer reading (brix% presumably) is a direct representation of the actual percentage of coolant in the emulsion. So to say, if we use 10L of oil and 190L of water we would then get a refractometer reading of 5%, but an actual concentration of 5%*1.5=7.5%?

If someone could explain all of this to me I would be extremely appreciative. It definitely seems like an area in which I would have benefited from some practical training!

Thanks a lot,

Leon.

Ianagos · Aug 4, 2020

Your colleague is wrong and you are correct.

Some coolants have a ratio of brix reading to concentration yours is 1.5 mine is 1:1 so it’s easy.

But a 5 brix reading would equal about 7.5% coolant. So the mix for 8% will read just over that and should take about 16liter or coolant concentrate for a 200liter tank

But do your own maths as it’s late and I’m in bed so maybe everything I said is bs.

Also the fact that you are in college yet you couldn’t read this on the manufacturers website hurts me a bit inside.

triumph406 · Aug 4, 2020

Don't waste your time with the Brix value of the coolant, at least I don't.

I run 5-7.5% concentration. I mix up accurate concentrations at 5%, 7.5% and 10%. That way I can calibrate the refractometer and see what concentration I actually have when checking the coolant.

In your case I'd make up 7%,8% and 9% concentrations to calibrate the refractometer.

Your adding 16L of concentrate to 184L of water to get 8% is correct.

LeonUoS · Aug 4, 2020

Hi Mate,

Really appreciate the reply.

So this is to then say that the true coolant concentration is not in anyway changed by the refractive index of the coolant, rather, the refractometer reading simply needs to be adjusted to accomadate the brix to concentration ratio, if the true concentration is to be calculated? In which case, is it then safe to say that, the amount of coolant you need to get a given percentage concentration is unaffected by this ratio i.e. if the ratio was 2,3 or even 1 (as your own) I would still need 16L of oil in a 200L tank (despite the refractometer reading differing in each case)?

As for the college comments, hey, there's some things that a theoretical engineering knowhow won't help you with! Sometimes you just need a trade education to appreciate the practicalities of a problem. My focus is on metallurgy and tribology, so, any machining knowhow that I have was picked up over the last 11 months of office based research. Not to mention the fact that It's difficult to find answers to questions (on the manufacturers website or elsewhere) when the entire premise of your question is misinformed.

In any case, thanks again for all the help mate, you've proven to be quite the lifesaver!

Cheers!

LeonUoS · Aug 4, 2020

Thanks alot for that mate, really helps, much appreciated!

litlerob1 · Aug 4, 2020

A million to zero is the ratio.

R

Ianagos · Aug 4, 2020

LeonUoS said:
Hi Mate,

Really appreciate the reply.

So this is to then say that the true coolant concentration is not in anyway changed by the refractive index of the coolant, rather, the refractometer reading simply needs to be adjusted to accomadate the brix to concentration ratio, if the true concentration is to be calculated? In which case, is it then safe to say that, the amount of coolant you need to get a given percentage concentration is unaffected by this ratio i.e. if the ratio was 2,3 or even 1 (as your own) I would still need 16L of oil in a 200L tank (despite the refractometer reading differing in each case)?

As for the college comments, hey, there's some things that a theoretical engineering knowhow won't help you with! Sometimes you just need a trade education to appreciate the practicalities of a problem. My focus is on metallurgy and tribology, so, any machining knowhow that I have was picked up over the last 11 months of office based research. Not to mention the fact that It's difficult to find answers to questions (on the manufacturers website or elsewhere) when the entire premise of your question is misinformed.

In any case, thanks again for all the help mate, you've proven to be quite the lifesaver!

Cheers!

Yes if you want an 8% concentration there is no way other than mixing in 8% colorant concentration (typically by volume).

Yes the percentage is unaffected by the ratio it is simply a ratio so you know what the reading should be for a given concentration.

And I mean if you are working on a PhD I’d think your reading comprehension and research skills are way beyond mine and within 15 seconds (took that long for the page to load mostly...) on my phone I found a sheet that would explain this to you.

http://backend.qualichem.com/product_docs/df183_Xtreme Cut 250C (1.12.15).pds.pdf

https://pdocs.masterchemical.com/mc...olant-Concentration-Facts-and-Terminology.pdf

Here is the important part

A Brix factor
is meaningful only as a multiplier; it does not indicate anything about a product’s efficacy or water content. A refractometer reading is meaningful only as a number to be multiplied by the Brix factor, not as an indicator in itself

CAMasochism · Aug 5, 2020

LeonUoS said:
I'm a PhD student studying cryogenic cutting fluids, where, as part of my PhD i'm hoping to undertake a cost analysis of cryogenic coolants compared to typical metalworking fluid (specifically Blaser Vasco 7000).

I'm sure that in some certain use cryogenic can have an effect, but yeesh. With it's cost you might as well see if shredded hundred dollar bills also work.

DDoug · Aug 5, 2020

CAMasochism said:
I'm sure that in some certain use cryogenic can have an effect, but yeesh. With it's cost you might as well see if shredded hundred dollar bills also work.

Machinery magazine article from 1950-1960's...showing Canadian shop working some "exotic" parts
on a VBM using liquid CO2 at the tool.

TeachMePlease · Aug 5, 2020

digger doug said:
Machinery magazine article from 1950-1960's...showing Canadian shop working some "exotic" parts
on a VBM using liquid CO2 at the tool.

I've experimented with "supercritical" CO2 delivered directly at the tool tip.

Cost to benefit ratio wasn't there.

DDoug · Aug 5, 2020

TeachMePlease said:
I've experimented with "supercritical" CO2 delivered directly at the tool tip.

Cost to benefit ratio wasn't there.

Yabutt !

Your in Florida.....article was about a company in Canada.....

Wiley QualiChem · Sep 9, 2020

LeonUoS said:
Hi Everyone,

I'm a PhD student studying cryogenic cutting fluids, where, as part of my PhD i'm hoping to undertake a cost analysis of cryogenic coolants compared to typical metalworking fluid (specifically Blaser Vasco 7000).

I have recently come into the problem of calculating how much coolant concentrate would be needed to fill a 200L tank to 8% concentration. Intuitively, I had assumed that that would simply mean adding 16L of concentrate to 184L of water, however, upon asking a machinist colleague he informed me that due to the refractive index of the coolant (1.5), I would actually only need to use 5.3% (10.7L) of the coolant concentrate to achieve a true concentration of 8%.

This seems strange to me, I trust my colleague as he as a wealth of practical experience (of which I have almost none) however, surely the 'True' concentration would be the true proportion of the mixture which is oil (and in which case 8%), rather than the effective concentration of the oil when refractive index is accounted for?

If my colleague is correct, would this then be to say that the refractometer reading (brix% presumably) is a direct representation of the actual percentage of coolant in the emulsion. So to say, if we use 10L of oil and 190L of water we would then get a refractometer reading of 5%, but an actual concentration of 5%*1.5=7.5%?

If someone could explain all of this to me I would be extremely appreciative. It definitely seems like an area in which I would have benefited from some practical training!

Thanks a lot,

Leon.

All coolants are different. Some require a BRIX conversion, others do not. The manufacturer of the coolant will supply the conversion, sometimes called a "Refractive Index" or "Refractometer Index". The index is calculated by making known dilutions then observing the refractometer reading. If a 10% by volume solution doesnt read as 10 on the refractometer, then you know there is a conversion needed. If it reads 5, then you know the conversion is 2. That means anytime you read the coolant in the tank with a refractometer, you multiply the reading x 2 to know the % by volume concentration. Indexes can range from as low as 0.8 to as high as 4 or 5.

The index is important if you are relying on the refractometer for measuring concentration. For your needs, your instinct was correct. Measure by volume and you will know the % concentration.

Good luck.

Regards,
John Wiley
QualiChem, Inc.

ss_user · Jun 9, 2022

DDoug said:
Yabutt !

Your in Florida.....article was about a company in Canada.....

It seems that California thinks everything is toxic. Most stuff is but it depends on concentration (dose) and time. Nerve gas is 5 mg/m3/min roughly the same a CS but the effects are quite different.
Something I heard rather late in life ( I'm 4 score an 4 ;-))
"The difference between theory and practice is far larger than theory would predict".

RJT · Jun 10, 2022

I agree with John Wiley. Go with the manufacturers recommendations. There is no general rule for all coolants. They are formulated for different reasons and applications. Keeping them at the right (recommended) concentration and free of tramp oil is the secret to long life. Coalasers (sp?) used correctly have greatly improved our coolant life.

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LeonUoS

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triumph406

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LeonUoS

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LeonUoS

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litlerob1

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Ianagos

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CAMasochism

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TeachMePlease

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Wiley QualiChem

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