How do you calculate the boil-off rate of a cryogenic tank?

Divide the liquid lost to boil-off by the starting inventory. 8 gallons lost from 250 is 3.2% for the period, the Tank Boil-Off Rate calculator's own example; over 8 days that is 0.4% a day. The workbook works out the boil-off from the inventory balance: start + delivered - withdrawn - end.

Why show the rate per day?

Periods differ in length, and a tank's target or data sheet figure is usually per day. The rate per day is the period rate divided by its days, and the target for the period is the target per day times the days.

What does a rising boil-off rate mean?

More heat is getting into the liquid. On a vacuum-insulated tank, a steady climb with no change in use often points to the insulating vacuum; frost or sweating on the outer shell is another sign. Have the tank checked by its owner or supplier.

What target boil-off should I use?

The tank's own figure from its data sheet or supplier, or a baseline from your own readings when the tank was known to be good. The example targets are invented; boil-off also depends on how full the tank is and on the weather.

What if some withdrawals are not metered?

Then they are counted as boil-off. Gas taken from the vapour space by a process is only counted as withdrawn if it is metered, so record every flow you can before reading the boil-off as a loss.

Does the workbook use macros?

No. It is a plain .xlsx with ordinary formulas, tables and native charts. The Verify sheet re-checks the formulas against fixed test readings and shows Self-check: PASS.

Energy and Sustainability

Cryogenic Tank Boil-Off Log Excel Template

Boil-off = starting inventory + delivered − withdrawn − ending inventory, and the boil-off rate = boil-off ÷ starting inventory. Log every bulk cryogenic tank each period and see its boil-off per day against target, the value of the product lost, and the trend of any tank.

Free, and a plain .xlsx with no macros to enable. A CSV with live formulas and a printed how-to guide come with it.

Overview

This cryogenic tank boil-off log is a working Excel workbook for plant engineers, utilities and maintenance teams and gas buyers. Each tank and period is one row with the starting and ending inventory and what was delivered and withdrawn; what the balance cannot account for is boil-off. The workbook gives it as a share of the starting inventory for the period and per day, compares it with each tank's target, and prices the liquid lost. It ships with eight weeks of readings for six bulk tanks at a fictional food plant, so every tile and chart is filled in when you open it.

In the example the 6,000 gallon nitrogen tank lost about 0.3% of its inventory a day for five weeks, under its 0.4% target. Then the rate climbed to 0.44%, 0.52% and 0.61% a day, 171 gallons in the last week, with frost on the outer shell: a sign to have the vacuum checked. Its eight-week average of 0.38% a day is still under target, which is why the tank status follows the latest period. The argon tanks lose less liquid but the most money: 1,184 of the 3,289 lost across the site.

Every delivery and withdrawal has to be recorded, or it shows up as boil-off. The download is a plain .xlsx with no macros. A CSV with live formulas is also included for other tools; the dashboard, charts, dropdowns and self-check are in the .xlsx.

What this template includes

Setup sheet with your site, volume unit and currency, the near target band, and the tanks with product, capacity, target boil-off per day and product price
Readings table, one row per tank and period: start and end dates, starting inventory, delivered, withdrawn and ending inventory, with a Check column
Per period: days, boil-off, boil-off rate for the period and per day, the target for the period, points above target, a status in words and the value lost
Per tank: periods, boil-off, value lost, average and latest boil-off per day against target, periods above target and a status for the latest period
Dashboard with four tiles (periods logged, boil-off lost, value lost, periods above target), average boil-off per day against target by tank, the last eight periods of the tank you pick, and the tank and trend tables
Method sheet with every formula, and a Verify sheet that re-checks the formulas against an independent reference and the Tank Boil-Off Rate calculator (Self-check: PASS)
CSV with live formulas for the Readings table; the dashboard, charts, dropdowns and self-check are in the .xlsx

Suggested use case

Use it to track the boil-off of bulk liquid nitrogen, argon or oxygen tanks week by week, to spot a tank whose vacuum insulation is failing, or to put a value on the product your site loses to boil-off and venting.

How to use it

On Setup, type the site, volume unit and currency, and list your tanks with product, capacity, target boil-off per day and product price.
On Readings, give each tank and period a row: start and end dates, starting inventory, delivered, withdrawn and ending inventory.
Fix anything the Check column names.
Open the Dashboard: boil-off per day against target by tank, the value lost, and the trend of the tank you pick.

Frequently Asked Questions

How do you calculate the boil-off rate of a cryogenic tank?: Divide the liquid lost to boil-off by the starting inventory. 8 gallons lost from 250 is 3.2% for the period, the Tank Boil-Off Rate calculator's own example; over 8 days that is 0.4% a day. The workbook works out the boil-off from the inventory balance: start + delivered - withdrawn - end.
Why show the rate per day?: Periods differ in length, and a tank's target or data sheet figure is usually per day. The rate per day is the period rate divided by its days, and the target for the period is the target per day times the days.
What does a rising boil-off rate mean?: More heat is getting into the liquid. On a vacuum-insulated tank, a steady climb with no change in use often points to the insulating vacuum; frost or sweating on the outer shell is another sign. Have the tank checked by its owner or supplier.
What target boil-off should I use?: The tank's own figure from its data sheet or supplier, or a baseline from your own readings when the tank was known to be good. The example targets are invented; boil-off also depends on how full the tank is and on the weather.
What if some withdrawals are not metered?: Then they are counted as boil-off. Gas taken from the vapour space by a process is only counted as withdrawn if it is metered, so record every flow you can before reading the boil-off as a loss.
Does the workbook use macros?: No. It is a plain .xlsx with ordinary formulas, tables and native charts. The Verify sheet re-checks the formulas against fixed test readings and shows Self-check: PASS.