How impact tools use air
A pneumatic chipping hammer or riveting hammer drives a piston back and forth inside a barrel. At the end of each stroke the piston strikes a chisel, set or rivet snap. The energy of each blow depends on air pressure in the barrel, and the rate of blows depends on how quickly air can fill and exhaust the cylinder. When pressure at the tool falls, both drop together: the tool hits more softly and more slowly, and work takes longer.
Not every riveting tool works this way. It helps to separate three families:
| Tool type | How it uses air | Air-supply concern |
|---|---|---|
| Chipping and scaling hammers | Continuous percussive blows while the trigger is held | Sustained flow over long bursts; vibration and hose wear |
| Solid-rivet hammers (one-shot, slow-hit, fast-hit) | Short percussive bursts per rivet, with a bucking bar behind | Stable pressure for consistent head formation; regulator setting matters |
| Squeeze riveters | Cylinder closes jaws once per rivet | Pressure sets squeeze force; small volume per cycle |
| Pneumatic-hydraulic blind-rivet tools | Air drives a hydraulic intensifier to pull the mandrel | Short pulses per rivet; mandrel collection may use extra air via vacuum |
The supply must be designed for the tool that is actually used. Applying chipping-hammer assumptions to blind-rivet tools, or the reverse, leads to wrong sizing.
Read tool data correctly
Tool catalogues state air consumption at a rated pressure, usually 6.2 bar (89.9 psig), and often per minute of continuous running. Some state “average” consumption assuming a typical duty. Keep the original units, pressure and basis when you copy figures into a demand schedule. Mixing l/s, cfm and m³/min, or gauge and absolute pressures, causes errors that are hard to spot later.
Light and heavy chipping hammers, scalers and rivet guns differ widely, so use the maker’s figure for each model rather than a generic value. Where a tool’s data are missing, a short test on a metered branch gives a reliable figure.
Three time scales: blows, bursts and production cycles
Impact-tool demand looks different depending on how long you look:
- Blow by blow: each stroke takes a pulse of air; the hose and tool volume smooth this.
- Trigger burst: seconds to minutes of continuous use, when the tool takes its full rated flow. This is the interval that decides whether pressure holds at the tool.
- Production cycle: over a shift, the tool may be in use only part of the time while the operator positions work, changes chisels or inspects.
A compressor sized for the shift average will run out of air during long bursts or when several operators work together. A compressor sized for every tool at full flow at once is usually oversized. The right answer comes from a duty profile built in time order.
Pressure at the tool and the air path
Specify working pressure at the tool inlet while it runs. Between the compressor and the tool are a header, drops, a filter-regulator-lubricator, a hose reel, a whip hose and quick couplings. Each loses pressure in proportion to flow. On a chipping line, a long, thin hose and small couplers are the most common reason a tool rated at 6.2 bar (89.9 psig) is actually seeing much less under load.
- Size the drop and hose for the tool’s flow; follow the tool maker’s minimum hose bore.
- Keep hose length to what is needed; avoid daisy-chaining extensions.
- Use high-flow couplings rated for the tool’s flow; standard small couplers restrict heavy tools.
- Fit a whip hose to absorb vibration at the tool and protect the main hose and coupling.
- Check pressure with a gauge at the tool inlet while the trigger is held.
For solid riveting, use a regulator at the station so the operator can set pressure for the rivet size and material. Too high a setting can damage the work and overdrive the rivet; too low gives under-formed heads. Lock or mark the agreed setting. Raising the whole plant header to fix one weak tool costs about 7% more compressor power per extra bar and increases leakage everywhere; fix the branch instead. Our distribution piping page explains branch sizing.
Air preparation and lubrication
Impact tools are sensitive to water and dirt. Water washes out lubricant and causes rust inside the barrel, especially on tools left overnight. Rust and scale from old steel pipes wear the piston and valve. A sound arrangement is:
- a dryer at the station; a refrigerated dryer with a typical pressure dew point around +3 °C suits most fabrication shops;
- drop legs taken from the top of the header, with drains at low points;
- a filter and regulator close to each workstation;
- a lubricator, or daily oiling at the inlet, if the tool maker requires it; many percussive tools need oil to run and last.
Where oil mist from the exhaust is unacceptable, for example before painting or in clean assembly, choose tools designed for oil-free running or capture the exhaust. Keep the lubrication method consistent with the tool’s history; switching a well-oiled tool to dry air can shorten its life.
Build the duty profile and calculate demand
To size the supply without double-averaging:
- List each tool, its rated consumption at rated pressure, and the number in use.
- For each, estimate the trigger-on time per burst and the bursts per hour from observation or a short log.
- Work out the longest likely burst and how many tools may run together in the worst realistic case.
- Add auxiliaries on the same branch: blow guns, blind-rivet mandrel collectors, grinders, hoists.
- Add leakage measured on the branch, not a guessed percentage.
- Size the compressor for the sustained peak and the receiver for short overlaps above it.
Apply diversity once. If you already took a usage factor for each tool, do not apply another for the number of operators working together without checking the result against a real log. Our tool demand and diversity page goes deeper.
Storage, recharge and shared stations
A receiver near a riveting or chipping area supplies short overlaps when several tools run together, and the compressor recharges it between bursts. Storage only helps if the compressor has enough sustained capacity to recover before the next overlap. If bursts repeat faster than recovery, pressure falls step by step through the shift, and the problem looks like a weak compressor even though each event is short. Logging pressure over a full shift shows this clearly.
In shared workshops, a priority user such as a paint booth, a blast pot or a process machine can draw the receiver down when it starts. A pressure-sustaining valve or a separate branch protects critical users.
For temporary work, such as ship repair, structural fabrication, tank chipping or plant shutdowns, a portable diesel or electric compressor is often simpler than extending the plant network. Size it on the same duty profile, with the right hose sizes and an aftercooler or dryer where water is a problem.
Safety and work quality
Improving air supply should never weaken safety controls:
- use chisel retainers so the tool cannot be fired out of the barrel;
- fit whip checks or safety cables on hose connections;
- provide eye, hearing and hand protection; impact tools are loud and vibrate;
- consider low-vibration tools and limit exposure time for operators;
- shut off and vent the air before changing chisels or sets.
For riveting, the quality check (head shape, gauge, no cracks or damage) remains the acceptance test. Air supply changes should be confirmed against it.
Diagnosing weak or inconsistent tools
| Symptom | Likely cause | Action |
|---|---|---|
| Weak blows only during long bursts | Hose, coupling or branch too small for flow | Gauge at tool while running; upsize hose and couplers |
| Weak when several operators work | Station capacity or receiver too small for overlaps | Log header pressure and compressor load |
| Weak after weekends or in monsoon | Water in the tool, rust, washed-out lubricant | Drain and dry the air; oil the tool as specified |
| Rivet heads inconsistent | Regulator drifting, pressure fluctuating, operator setting | Set and lock regulator; check pressure stability |
| Tool runs slowly from new | Restricted inlet, wrong coupler, clogged inlet screen | Inspect fittings and screen |
| Pressure falls through the shift | Recharge slower than repeated demand | Add sustained capacity, not only storage |
How Reddy Compressors helps
Reddy Compressors has supported fabrication shops, foundries, shipyards, steel structures and plant maintenance teams since 2002 from our office at Tarnaka, Secunderabad. Our service teams cover all of Telangana and Andhra Pradesh, and we supply equipment, rentals and spares across India. For impact-tool supply we:
- measure pressure at the tools and log station flow during real work;
- sell and rent rotary screw and reciprocating compressors, new and used, plus dryers and receivers;
- supply portable diesel and electric compressors on hire for shutdowns and site fabrication through our rental service;
- service and maintain compressors of all major brands, with AMC options.
We are an independent multi-brand specialist (ELGi, Atlas Copco, Ingersoll Rand, KAESER, Chicago Pneumatic and others), not an authorised dealer. We have tie-ups with all major and reputed brands. Call +91 99590 60718 or +91 92468 88812.
What to send us
- Tool types, makes and models, and how many are used together
- Typical burst length and work pattern per shift
- Hose size, length and coupling type
- Pressure at the tool while running, if measured
- Compressor make, model, pressure setting and receiver size
- Whether the work is permanent or a temporary site job
Frequently asked questions
What air pressure does a chipping hammer need?
Most chipping hammers are rated at about 6.2 bar (89.9 psig) at the tool inlet, with some heavy tools specified up to about 7 bar (101.5 psig). What matters is the pressure at the tool while the trigger is held, not the compressor discharge. Check with a gauge fitted at the inlet during work, and correct hose, coupler or branch restrictions before raising plant pressure.
Why does my riveting gun lose power?
The usual causes are pressure drop in hoses and couplings, a regulator set too low or drifting, water and rust inside the tool, missing lubrication, or the station running short when several tools work together. Measure pressure at the tool during a burst. If it is low only under flow, the air path is restricting it; if the header falls too, capacity or storage is short.
How do I size a compressor for chipping hammers?
List each tool’s rated consumption, estimate realistic trigger-on time and the worst overlap of operators, then add auxiliaries and measured leakage. Size the compressor for the sustained peak and use a receiver for short overlaps. Avoid sizing from the shift average alone, which runs short during long bursts, or from every tool running at once, which usually oversizes.
Do pneumatic hammers need oiled air?
Many percussive tools need lubrication to run and last, either from an inline lubricator or by oiling the inlet daily, as the tool maker specifies. Some tools are designed for oil-free running. Water in the air washes oil out and causes rust, so dry, filtered air helps in every case. Where exhaust oil mist is unacceptable, choose oil-free tools or capture the exhaust.
What hose size should I use for a chipping hammer?
Follow the tool maker’s minimum hose bore and keep the hose as short as practical. Heavy chipping hammers need larger hoses and high-flow couplings than light tools, and a short whip hose at the tool absorbs vibration. Long runs of small hose, extensions joined in series and standard small couplers are common reasons tools hit weakly even with a healthy compressor.
Can I hire a compressor for a chipping or riveting job?
Yes. Portable diesel and electric compressors are commonly hired for shutdowns, tank and structure chipping, ship repair and site fabrication. Tell us the tools, how many run together, burst length, hose runs and whether water is a problem, and we size the machine, hoses and any aftercooler or dryer. Hire jobs are serviced every 300 running hours.
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.
Compressed air demand estimate
Add up the air your tools and processes use, apply duty and simultaneity, then add leakage and growth allowances to reach a capacity to enquire about.
The worked example below shows the method with fixed numbers. Turn on JavaScript to change the inputs.
Worked example
Inputs
- Unit for the air each tool uses: L/s
- Group A: number of tools: 6
- Group A: free air each (in the unit above): 4
- Group A: duty (%): 40
- Group B: number of tools: 2
- Group B: free air each (in the unit above): 15
- Group B: duty (%): 60
- Group C: number of tools: 1
- Group C: free air each (in the unit above): 40
- Group C: duty (%): 80
- Simultaneity of all tools (%): 65
- Leakage allowance (%): 15
- Growth allowance (%): 10
Result
- Connected demand: 94 L/s = 199 cfm
- Average demand (duty-weighted): 59.6 L/s = 126 cfm
- Simultaneous peak: 61.1 L/s = 129 cfm
- Design basis (higher of average and peak): 61.1 L/s = 129 cfm
- Design capacity with allowances: 77.29 L/s = 4.64 m³/min = 163.8 cfm
Method. Average demand = Σ(number × air per tool × duty). Peak = Σ(number × air per tool) × simultaneity. The peak can never be lower than the average, so the design basis is the higher of the two. Design capacity = design basis × (1 + leakage) × (1 + growth).
What to take from it. Leakage and growth allowances move the answer as much as any single tool. Where you can, replace catalogue figures with measured ones.
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.
Receiver storage sizing
Estimate the receiver volume needed to ride through a short burst of demand without the pressure falling below the limit.
The worked example below shows the method with fixed numbers. Turn on JavaScript to change the inputs.
Worked example
Inputs
- Burst demand above compressor output (m³/min free air): 5
- Burst duration (s): 20
- Allowed pressure fall (bar): 0.7
- Receiver volume you already have (litres; 0 to skip the hold-up check): 1520
Result
- Receiver volume needed: 2,412 litres
- 2.41 m³
- Practical size (with 25% margin): 3,016 litres
- Hold-up time of the receiver you have: 12.6 s before the pressure falls by 0.7 bar
Method. V = Q × t × P_atm / ΔP, where Q is the shortfall in free air (m³/min), t the time (min), ΔP the allowed pressure fall (bar) and P_atm = 1.013 bar. The same relation gives the hold-up time of an existing receiver: t = V × ΔP / (Q × P_atm). Isothermal; for a real system add a margin.
What to take from it. A receiver buys time. It does not create capacity: once it is spent the pressure keeps falling until the compressors catch up.