BIZOMAT MAKEOS · Maintenance
Coolant Tank Maintenance (Concentration, Correction, Make-Up Mix, Usage)
What is the coolant concentration from my refractometer reading, what do I add to correct it, what make-up mix keeps it on target, and how much concentrate will I use?
Maintenance plan for a water-mixed metalworking fluid sump: concentration from the refractometer reading and the product factor, the concentrate or water to add to bring it to target (as the refractometer concentration tool), the make-up mix strength that holds the target when water evaporates and mixed fluid is dragged out on chips and parts, the daily make-up volume, and concentrate use and cost per month.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Refractometer reading | °Brix | Reading on the refractometer scale. |
| Refractometer factor for the product | Refractometer factor of the coolant product (from its data sheet). | |
| Target concentration | % | Concentration the supplier recommends for the work. |
| Sump volume | L | Working volume of fluid in the sump. |
| Water evaporated per day | L/day | Water lost by evaporation each day (only water leaves). |
| Mixed fluid dragged out per day | L/day | Mixed fluid carried away on chips, parts and leaks each day. |
| Working days per month | Working days per month. | |
| Concentrate price | $/L | Price of the concentrate. |
| Accepted deviation from target | % | Plus-or-minus deviation from target you accept before correcting (as a share of the target). |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Refractometer reading
- What it is
- The reading on the refractometer scale for a sample of the coolant drawn from the sump. It is converted to concentration with the product factor.
- Units and format
- Enter a number in °Brix: °Brix. The form accepts 0 °Brix to 30 °Brix. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 °Brix as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Concentration is the reading times the factor, so it moves in direct proportion.
- Get it right
- Skim tramp oil and clean the prism first; oil raises the reading.
What this means: Refractometer factor for the product
- What it is
- The multiplier that turns the refractometer reading into concentration for this particular coolant product, given on the product data sheet.
- Units and format
- Enter a plain number with no unit. The form accepts 0.5 to 5. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.6 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Concentration rises in direct proportion to the factor.
- Get it right
- Each product has its own factor; use the one for the concentrate in the sump.
What this means: Target concentration
- What it is
- The concentration of concentrate in the mixed fluid you want to hold, as recommended by the coolant supplier for the work being done.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0.5% to 30%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 7% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher target raises the make-up strength and the concentrate used per month.
- Get it right
- Type the percentage itself, not a fraction.
What this means: Sump volume
- What it is
- The volume of mixed fluid actually in the sump and system when it is at its working level.
- Units and format
- Enter a number in L: litres. The form accepts 0.000001 L to 1000000 L. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 400 L as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The amount of concentrate or water needed to correct the concentration is proportional to it.
- Get it right
- Use the working volume, not the full tank capacity.
What this means: Water evaporated per day
- What it is
- The water lost from the sump to the air each day. Only water leaves this way, so the remaining fluid gets stronger.
- Units and format
- Enter a number in L/day: L/day. The form accepts 0 L/day to 100000 L/day. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 L/day as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More evaporation weakens the make-up mix needed to hold the target.
- Get it right
- Do not include fluid carried out on chips; that goes in drag-out.
What this means: Mixed fluid dragged out per day
- What it is
- The mixed fluid (water and concentrate together) carried out each day on chips, parts and through leaks.
- Units and format
- Enter a number in L/day: L/day. The form accepts 0 L/day to 100000 L/day. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 L/day as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More drag-out raises the make-up strength and the concentrate used per month.
- Get it right
- Estimate it from top-up records minus evaporation if you cannot measure it directly.
What this means: Working days per month
- What it is
- The number of days per month the machines run and lose fluid, used to turn daily concentrate use into monthly use and cost.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 31. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 22 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Monthly concentrate use and cost rise in proportion.
What this means: Concentrate price
- What it is
- What you pay for one litre of the coolant concentrate, as bought.
- Units and format
- Enter a number in $/L: money per L. The form accepts $0/L to $1000/L. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $6/L as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Monthly concentrate cost rises in direct proportion.
What this means: Accepted deviation from target
- What it is
- How far the measured concentration may drift from the target, either way, before you correct it. It is a share of the target, not percentage points of concentration.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 50%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Ten percent of a target is not the same as ten percentage points; this tool uses the share of the target.
Method and formulas
- Concentration = reading × factor; correction to the target (as the refractometer concentration tool).
- Steady make-up strength c_m = target × drag-out ÷ (drag-out + evaporation), because only water evaporates.
- Daily make-up = drag-out + evaporation; concentrate per day = make-up × c_m; per month = per day × days.
- Example: 4 °Brix is 6.4%; add 2.5806 L of concentrate; top up with a 2.3333% mix, using 7.7 L of concentrate a month.
Limitations
- Uniform losses; tramp oil raises refractometer readings and must be removed first.
- Concentration correction assumes undiluted concentrate or clean water is added.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Correct a machine sump to its target concentration
- Set the make-up mix ratio
- Budget coolant concentrate use
Who it is for
- Machine operators
- Maintenance technicians
- Production supervisors
What you get
- Actual concentration and the correction to make
- Make-up mix strength and daily volume
- Concentrate use and cost per month
Interpreting the result
- Topping up with neat water lets the concentration fall with drag-out; with neat concentrate it climbs as water evaporates.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1176–1181. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Useful alongside · BIZOMAT original book
Quenching the hot layer
In Induction Hardening by the Numbers
What it covers: Turning the heated layer into martensite: spray quenching and polymer quenchants, how fast is fast enough, the quench tank's heat balance per part and per hour, and a summer rush that warmed the bath.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Coolant Tank Maintenance (Concentration, Correction, Make-Up Mix, Usage) calculator