Why a survey alone does not save air
A leak survey produces a list of defects. Air is only saved when those defects are repaired, and the saving is only known when the repair is checked and the system leakage is measured again. Between survey and saving there are several places where findings disappear: tags fall off, photographs are not linked to locations, work orders are closed without a recheck and new leaks appear while old ones are still open.
A register closes those gaps. It gives maintenance a clear work list, gives management a measure of progress and gives the energy team evidence. It also keeps separate four things that are often confused: an estimated leak flow, a completed repair, a verified closure at the leak point and a measured reduction in system leakage.
What a good leak register records
| Field | Purpose | Example of good practice |
|---|---|---|
| Leak ID | A permanent identity for the life of the finding | Zone prefix plus number, never reused |
| Location and component | Lets anyone find it again | Building, bay, machine, line and the exact fitting, with a photograph |
| Date found and method | Traceability | Ultrasonic survey, acoustic camera or leak-detection fluid |
| Conditions | Context for the size estimate | Local pressure and whether the machine was running |
| Size category or estimate | Supports prioritisation | Small, medium, large, or a flow estimate with its method stated |
| Priority | Orders the work | Safety or quality impact first, then air loss and ease of repair |
| Owner and target date | Accountability | A named role or team, and a planned maintenance window |
| Parts needed | Avoids repeat visits | Seal kit, coupling, hose, drain valve, regulator |
| Repair record | Shows what was done | Date, work order, action taken, parts used |
| Recheck result | Confirms closure | Date, method, conditions and pass or fail |
| Status | Tracks progress | A fixed list of status values used by everyone |
Keep the field list short enough that technicians will actually fill it in on the shop floor. A register with twenty columns that nobody completes is less useful than one with ten that are always filled.
A spreadsheet is enough for most plants. Larger sites may hold the register in their maintenance management system. What matters is a single master list with one row per leak and a history that is added to, not overwritten.
Giving each leak a stable identity
Assign the ID at the moment of detection and keep it until the leak is closed and verified. Use a zone or building prefix so that two survey teams cannot create the same number. A physical tag at the leak point helps the repair team, but the register must contain enough description and photographs to find the leak if the tag is lost.
Do not use a photograph file name as the identity, because files get renamed and one leak may have several images. Link images to the leak ID. If a later survey finds that two records describe the same leak, mark one as a duplicate with a note rather than deleting it. Where several contractors work on the site, agree a common numbering method and status list so the same defect is not renumbered by each team.
Status values that keep the list honest
- Open: found and recorded, not yet planned.
- Planned: owner assigned, parts identified, repair window agreed.
- Awaiting shutdown or parts: cannot be repaired until a stated event.
- Repaired, not verified: work done, recheck still to be carried out.
- Closed, verified: rechecked under suitable conditions and no leak detected.
- Repair failed: recheck found the leak still present; the record returns to planned with a note.
- Not repaired, accepted: a deliberate decision, for example equipment due for removal, with the reason recorded.
- Duplicate or not a leak: closed with an explanation.
Only “closed, verified” should count as a fixed leak in progress reports. Counting “repaired, not verified” items as savings is the most common way leak programmes overstate their results.
Recording the as-found condition
The record made at detection should not be changed after repair, except for clearly marked corrections. It should state who found the leak, when, by which method, at what local pressure and with the equipment in which state. Distinguish continuous leaks from those that appear only when a machine cycles, and note any access limits.
If a flow estimate is recorded, keep the method and assumptions with it. Ultrasonic level readings indicate relative size but are not direct flow measurements. Treat individual estimates as a guide for prioritisation and confirm the total with a system leakage test.
Planning and carrying out repairs
- Group by area: a technician can close many leaks in one bay in a single visit.
- Group by part: issue couplings, seal kits, drains and hoses to stores before the round starts.
- Use the right repair: retightening may cure a fitting for a while; a worn seal or cracked hose needs replacement.
- Follow isolation procedures: depressurise and isolate under the site’s rules before dismantling any fitting.
- Record the action: what was done, which parts were used and the work-order number, against the leak ID.
- Remove dead legs: where a leak is on abandoned pipework, isolating or removing the branch is often the better repair.
Verifying the repair and the saving
Verification happens at two levels. At the leak point, recheck with the same or an equivalent method under comparable conditions: similar pressure, with the equipment in the same operating state as when the leak was found. Record the date, method and result against the leak ID.
At system level, repeat the leakage test used at the start of the programme, such as a load/unload timing test or a pressure-decay test during non-production, at a comparable header pressure. Compare the before and after figures, noting any change in system volume, pressure, connected equipment or compressor that could affect the comparison. New leaks found during the period should be recorded, because they explain why the total may fall less than the sum of individual repairs.
| What you can claim | Evidence needed |
|---|---|
| Leaks repaired | Repair records against leak IDs |
| Leaks closed | Recheck results at the leak point |
| Leakage reduced | Before and after system leakage tests at comparable conditions |
| Energy saved | Reduced leakage combined with measured compressor power or specific power, in kWh |
Reporting progress to management
- Leaks found, closed and verified, open and overdue, by zone.
- Age of open leaks and the reason for any overdue items.
- Repair failure rate, which points to poor parts or methods.
- Recurrence by location or component type, which points to design or wear problems.
- System leakage trend from repeated tests.
- Estimated energy effect in kWh, with the method stated, leaving the tariff to the plant’s own figures.
How Reddy Compressors helps
We set up and run leak repair registers as part of our leak detection and compressed-air audit work. After an ultrasonic survey we hand over a register with a permanent ID, location, photograph, size category and priority for each leak, together with a parts list. Our technicians can carry out the repair round, recheck each point and repeat the system leakage test so you have verified figures rather than estimates.
We are an independent multi-brand specialist that sells, rents and services ELGi, Atlas Copco, Ingersoll Rand, KAESER, Chicago Pneumatic and other makes, and we supply couplings, hoses, drains, regulators and compressor spares. Many customers combine periodic leak surveys and register updates with an AMC, so the programme continues instead of ending after one round. Once leakage falls, we can review whether your pressure set point and compressor mix should change.
Our office is at Tarnaka, Secunderabad, and our service teams cover Telangana and Andhra Pradesh. Call +91 99590 60718 or +91 92468 88812.
What to send us
- Your existing leak survey report, tag list or spreadsheet, if any.
- Plant layout or zone list.
- Compressor makes, models and running pressure.
- How your maintenance work orders are raised and closed.
- When non-production windows are available for system leakage tests.
- Whether you want us to carry out repairs, rechecks or both.
Frequently asked questions
What should a compressed-air leak register include?
At minimum: a permanent leak ID, exact location and component, photograph, date and method of detection, local pressure, size category or estimate, priority, owner, target date, parts needed, repair record, recheck result and status. Keep one row per leak and add history rather than overwriting it, so the record shows what was found, what was done and whether the repair was confirmed.
How do I verify that a compressed-air leak has been fixed?
Recheck the leak point with the same or an equivalent method, such as an ultrasonic detector, under similar conditions to the original finding: comparable pressure and the equipment in the same operating state. Record the date, method and result against the leak ID. A closed work order shows that work was done, but only the recheck confirms the leak has stopped.
How do I measure the saving from a leak repair programme?
Repeat the system leakage test you used at the start, such as a load/unload timing test or a pressure-decay test during non-production, at comparable header pressure. The fall in leakage flow, combined with measured compressor power or specific power, gives the energy effect in kWh. Note any changes in equipment, pressure or system volume that might affect the comparison.
Why do compressed-air leaks come back after repair?
Some repairs only treat the symptom, such as retightening a fitting with a worn seal. Others fail because of vibration, heat, poor parts or incorrect installation. New leaks also appear as hoses age and equipment changes. A register reveals patterns: if the same component type or location keeps leaking, the fix may be a different part, better support or a design change.
Can I use a spreadsheet as a leak register?
Yes. For most plants a well-structured spreadsheet works well, provided there is one master copy, a fixed list of status values and one row per leak with a permanent ID. Link photographs by ID rather than by file name. Larger sites may prefer their maintenance management system, but the fields and rules matter more than the software.
Who should own leak repairs in a plant?
Every leak should have a named owner, usually the maintenance team responsible for that area or equipment, with a target date tied to a maintenance window. The energy or utilities team often owns the register itself and reports progress. Where outside technicians carry out repairs, they should record their work against the same leak IDs so the history stays in one place.
Related pages
Calculators and worked examples
These tools give indicative figures for screening, comparison and for preparing an enquiry. They run in your browser and send nothing. No prices or tariffs are assumed: enter your own to see costs. Efficiencies and other figures shown are example values: replace them with your own. Results are not a performance guarantee or a design certificate; final selection is confirmed by a service engineer against the machine data sheet and the site.
Leak repair persistence
For one cohort of verified repairs that has reached its follow-up date, report inspection coverage, persistence and recurrence separately, with the evidence gap and the air still being lost.
The worked example below shows the method with fixed numbers. Turn on JavaScript to change the inputs.
Worked example
Inputs
- Number of eligible repairs (follow-up date passed): 120
- Number of repairs re-checked: 90
- Number of repairs still passing: 72
- Number of repairs leaking again (recurred): 18
- Number of recurrences in the most frequent component group: 11
- Estimated flow of recurred leaks (m³/min): 0.9
- Estimated flow of new leaks found nearby (m³/min): 0
- Specific power (kW per m³/min): 7
- Running hours per year: 6000
Result
- Inspection coverage: 75 % (90 of 120)
- Persistence rate: 80 % of re-checked repairs still pass
- Recurrence rate: 20 % of re-checked repairs leak again
- Other outcomes among re-checked: 0 repairs (neither passing nor recurred)
- Unknown status: 30 eligible repairs not yet re-checked
- Persistence range over all eligible: 60–85 % (all unknowns failed – all unknowns passed)
- Most frequent component group: 61.1 % of recurrences (11 of 18)
- Residual leak flow: 0.9 m³/min (32 cfm)
- Compressor power for residual leaks: 6.3 kW
- Energy per year: 37,800 kWh
- Cost per year: Enter your electricity tariff (cost per kWh) above
Method. Coverage = re-checked ÷ eligible. Persistence = still passing ÷ re-checked; recurrence = leaking again ÷ re-checked (inspected items only). Unknown = eligible − re-checked. The persistence range assumes every unknown repair failed (low) or passed (high), each over all eligible repairs. Residual flow = estimated flow of recurred leaks + new leaks nearby; power = flow × specific power. Other outcomes = re-checked − passing − recurred (for example component removed). Default: the page example (120 eligible, 90 re-checked, 72 passing, 18 recurred, 11 of them quick couplings, 0.9 m³/min).
What to take from it. Report coverage beside persistence. A high persistence figure from a low coverage describes a small, possibly unrepresentative sample.
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer, Reddy Compressors. Last updated 17 October 2026. How our engineering content is reviewed.