Aircraft deicing fluid: converting a Type IV mix ratio to actual glycol volume
A ground crew trainee assumed 'Type IV mix' meant pure glycol regardless of ratio, and ordered concentrate as if the whole tank volume was straight fluid — the actual glycol content depends entirely on the mix percentage
We write the way we argue on the bench: exact factor, one sharp trap, one worked example you can re-check.
A ground crew trainee assumed 'Type IV mix' meant pure glycol regardless of ratio, and ordered concentrate as if the whole tank volume was straight fluid — the actual glycol content depends entirely on the mix percentage used that day.
I still keep a screenshot of this relationship because memory is where the wrong cousin of a unit sneaks in.
The factor that settles arguments
This is the relationship our converters use. Screenshot it if you have to — just stop re-deriving it from a half-remembered blog post.
A 75/25 Type IV glycol/water mix: 1 L total mix = 0.75 L glycol concentrate
Write that line once at the top of your notes. Every later arithmetic step should point back to it instead of inventing a friendlier number mid-stream.
The mistake that keeps showing up
Assuming a deicing fluid's mix ratio (like 75/25 or 50/50) doesn't matter for ordering concentrate, and treating the total sprayed volume as if it were all glycol.
I still write the unit next to every intermediate value. It looks pedantic until it catches the one swap that would have shipped wrong.
- Write down the known value in L total deicing mix (75/25 Type IV).
- Confirm the target unit is really L glycol concentrate, not a similar-looking one.
- Apply the factor: A 75/25 Type IV glycol/water mix: 1 L total mix = 0.75 L glycol concentrate.
- Round only at the end, to the precision your tool or spec supports.
Worked example
A deicing operation uses 200 L of a 75/25 Type IV glycol/water mix.
200 L total deicing mix (75/25 Type IV) × 0.75 = 150 L glycol concentrate
That's 150 L glycol concentrate — round only to the precision your tool or spec actually needs.
I usually convert once, write the answer with units, then convert back. That two-step habit has saved more weekends than any fancy app.
Quick reference table
| L total deicing mix (75/25 Type IV) | Calculation | L glycol concentrate |
|---|---|---|
| 1 | 1 × 0.75 | 0.75 |
| 2 | 2 × 0.75 | 1.5 |
| 5 | 5 × 0.75 | 3.75 |
| 10 | 10 × 0.75 | 7.5 |
Use the table for speed once you trust the factor. Do not use it as a substitute for understanding which definition of the unit you are on.
Why the exact number matters
Deicing fluid concentration is chosen based on outside air temperature and precipitation conditions — under-ordering concentrate for a colder mix ratio can leave a crew without adequate protection fluid mid-operation.
Precision is not about showing off decimals. It is about making sure the shopping list, the machine setting, and the acceptance check are all describing the same physical quantity.
Pocket recap
Multiply the total mix volume by the glycol percentage to get actual concentrate — 200 L of a 75/25 mix contains 150 L of glycol concentrate.
Keep the converter link nearby for the next time the same debate shows up in a group chat. Re-typing the factor from memory is how the wrong cousin of a unit sneaks back in.
Try the converters mentioned in this article
FAQ
What is the exact L total deicing mix (75/25 Type IV) to L glycol concentrate factor here?+
A 75/25 Type IV glycol/water mix: 1 L total mix = 0.75 L glycol concentrate
Should I round partway through the calculation?+
No — carry full precision through the multiplication and round only the final answer, to the precision your tool, gauge, or spec actually supports.
What's the single biggest mistake people make with this conversion?+
Assuming a deicing fluid's mix ratio (like 75/25 or 50/50) doesn't matter for ordering concentrate, and treating the total sprayed volume as if it were all glycol.
This article was written by The Turbo Unit Converter engineering desk (Applied units & field metrology) and last reviewed on 2026-07-23 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.