Air-Leg Rock Drill Vibration Reports: ISO 28927-10 Scope and Buyer Checks

September 19, 2026

Air-leg pneumatic rock drill vibration test setup with handle sensor and controlled air supply

Short answer: do not accept an “ISO 28927-10 vibration value” for an air-leg or jackleg rock drill without checking the test scope. ISO 28927-10 covers many hand-held percussive machines, but its published scope explicitly excludes jackleg-type and push-feed rock drills because their feed force is supplied by an additional device rather than by the operator’s hands. For an air-leg drill, buyers therefore need a clearly identified measurement method, the complete test configuration, uncertainty, raw report traceability and a plan for site exposure assessment. A single acceleration number is not enough to compare suppliers or predict an operator’s daily exposure.

This guide is for mines, tunnelling contractors, quarries, distributors and procurement teams evaluating pneumatic air-leg rock drills. It explains what a defensible vibration report should contain, how to compare two offers and where laboratory evidence stops. It does not replace a competent occupational-hygiene assessment under the rules that apply at the operating site.

Why the test-standard claim must be checked first

ISO 28927-10:2011 specifies a laboratory method for vibration emission from hand-held percussive drills, hammers and breakers. Its scope also states that the method is not applicable to jackleg-type rock drills or push-feed rock drills. That exclusion matters for models in which a pneumatic leg supports and advances the drill: feed force, machine attitude and the interaction among the drill, leg, steel and rock are part of the operating system.

The practical procurement conclusion is conditional, not absolute. ISO 28927-10 can still help a buyer understand terminology or question a supplier’s method, but a supplier should not present an air-leg result as conforming to that standard when the machine configuration falls outside its stated scope. Ask the laboratory or manufacturer to identify the alternative method used and explain how the rig represents intended field use.

The UK Health and Safety Executive’s research report RR1164 also illustrates why test-code details matter. Its investigation of ISO 28927-10 for percussive drills, hammers and breakers examined how well a declared emission test represents real use. The broader lesson for procurement is straightforward: even where a standard is applicable, the declared value must be read together with the test method and operating conditions.

Three different questions that buyers should not mix

Question	Evidence needed	What it can support	What it cannot prove alone
What did this drill produce in a defined test?	Controlled measurement report with method, configuration, result and uncertainty	Comparison under matched and documented conditions	Daily operator exposure at a mine or tunnel
What happens during our actual drilling task?	Representative workplace measurement and task observation	Site-specific exposure assessment	Performance of every operator, rock type or maintenance condition
How should exposure be controlled?	Local legal requirements, competent risk assessment, operating time and control plan	Work planning, engineering controls, maintenance and health-surveillance decisions	Product acceptance based on one catalogue value

A product test and a workplace exposure assessment are related, but they are not interchangeable. HSE’s hand-arm vibration guidance treats magnitude together with exposure duration and actual use. Procurement should therefore use supplier data to screen and compare evidence, while the employer uses representative site data to manage exposure.

What a credible air-leg rock drill vibration report should identify

Request the full report or a controlled extract before technical approval. The evidence should be traceable to the exact configuration offered, not to an unspecified “equivalent” drill.

Report item	Buyer check	Why it matters
Machine identity	Model, revision, serial or sample ID, mass and handle configuration	Prevents a result from another model or prototype being reused
Air-leg identity	Leg model, length, support arrangement and control configuration	The leg changes support, feed behaviour and machine attitude
Drill string	Shank, steel length, bit type, bit diameter and wear condition	The striking and rock-contact system affects measured vibration
Operating supply	Air pressure at the tool inlet during drilling, hose arrangement and lubrication condition	Compressor or header pressure alone does not establish tool-inlet conditions
Test medium	Rock or test-block description, support and hole condition	Hardness, fractures, collaring and contact stability change the drilling response
Measurement method	Method name, edition, deviations, sensor type, mounting and handle position	Allows a reviewer to judge whether the method fits an air-leg machine
Result presentation	Frequency weighting, axes, averaging process, number of runs and reported uncertainty	A bare value in m/s² lacks the context needed for comparison
Traceability	Laboratory, test date, report number, instrument calibration status and approval signature	Makes the evidence auditable during supplier qualification

How to compare two supplier reports

First compare the evidence, then compare the result. A lower number from an undocumented or non-equivalent test should not outrank a higher number from a well-controlled, relevant report.

Confirm both products are the same machine class. Separate air-leg, handheld sinker and stoper configurations. Do not assume that a result for a free hand-held drill applies to a leg-fed drill.
Check whether each cited method covers the tested configuration. If a report cites ISO 28927-10 for an air-leg drill, require a written explanation of the scope issue and any deviations. “Tested according to ISO” is not enough.
Normalize the configuration. Compare the same or equivalent air leg, drill steel, bit diameter, test medium, operating pressure and lubrication state. Record every unavoidable difference.
Read uncertainty with the measured value. A result without uncertainty suggests more precision than the test can support. Where result ranges overlap, do not claim that one drill is definitively lower-vibration without further evidence.
Check repeatability. Look for multiple runs and a stated treatment of variation. One short run can hide instability caused by collaring, steel alignment or test-block variability.
Separate emission evidence from exposure planning. Use the comparison to select samples for a controlled field trial; do not convert an unmatched laboratory number directly into a safe daily operating time.

Convert Defensible Field Data Into an A(8) Screening Decision

A supplier vibration report and an operator exposure assessment answer different questions. For an air-leg drill, do not calculate a daily operating time from a catalogue value, an ISO 28927-10 claim that does not cover the tested jackleg configuration, or a short laboratory run with unknown field relevance. An exposure screen needs a representative frequency-weighted vibration magnitude for the real task and the operator’s actual daily trigger time.

When those inputs have been accepted by the site’s competent vibration assessor, the single-task screening relationship is:

A(8) = a_hv × √(T ÷ 8)

a_hv is the representative vibration total value in m/s² for the task and configuration being assessed.
T is actual daily trigger time in hours: the time the operating drill transmits vibration to the operator’s hands, not the full shift, hole-cycle or equipment-availability time.
8 is the eight-hour reference period used for A(8).

For several tools or processes in one day, combine their partial exposures by energy, not by adding the A(8) values directly:

A_total(8) = √Σ[a_hvi² × (T_i ÷ 8)]

Worked arithmetic example

Assume a competent field assessment establishes a representative value of 10 m/s² for one controlled jackleg-drilling task and observation establishes 30 minutes, or 0.5 hour, of actual trigger time per operator per day:

A(8) = 10 × √(0.5 ÷ 8) = 2.5 m/s².

This is illustrative arithmetic, not a PerfoMax product declaration or a universal safe-time recommendation. Under the UK HSE framework it reaches the exposure action value; the applicable action and limit values, measurement method, uncertainty treatment and control duties must be confirmed for the operating jurisdiction. A different drill, handle, leg, rock, bit, pressure, maintenance state, operator grip or trigger time can change the result.

Evidence state	Buyer or site decision allowed	Decision not supported	Next evidence required
Supplier gives one acceleration number with no method, configuration or uncertainty	HOLD REPORT	Supplier ranking, A(8), trigger-time limit or field release	Complete method, machine configuration, result definition, uncertainty and traceable report
Report cites ISO 28927-10 for a jackleg or push-feed configuration without resolving the published scope exclusion	HOLD METHOD CLAIM	Standards compliance, direct model comparison or exposure calculation	Written method justification, deviations, repeatability, uncertainty and evidence that the result represents the offered configuration
Controlled supplier or laboratory result is traceable but field representativeness is not established	PROCUREMENT SCREEN ONLY	Operator daily exposure or safe drilling duration	Controlled site trial and representative task measurement planned by a competent assessor
Representative field magnitude and measured trigger time are available for one controlled task	CALCULATE PARTIAL A(8)	Whole-shift approval if the operator uses other vibrating tools or conditions vary materially	Record uncertainty, task boundary and all other daily vibration exposures
Representative values and trigger times exist for every vibrating task in the shift	COMBINE DAILY EXPOSURE	Permanent release when work pattern, equipment or controls later change	Compare with the applicable jurisdictional values, implement the required controls and set a review trigger
Drill, air leg, handle, steel, bit, pressure, rock, maintenance condition or work pattern changes	REASSESS	Automatic transfer of the earlier A(8) result	Document the change and repeat or update the representative assessment

Copy-ready vibration evidence and exposure-screen record

Site, heading/quarry area, task and assessment date:
Operator group and representative work pattern:
Drill, air-leg, handle and configuration identifiers:
Drill steel, bit, hole, rock and flushing conditions:
Tool-inlet pressure, lubrication and maintenance state:
Measurement method, axes, weighting, sensor position and calibration:
Representative vibration magnitude and uncertainty:
Observed trigger-time method and daily trigger time:
Other vibrating tools/processes and their inputs:
Partial and combined A(8) result:
Applicable jurisdiction, action/limit values and competent assessor:
Required controls, operating boundary and reassessment trigger:
Decision: HOLD REPORT / PROCUREMENT SCREEN ONLY / FIELD ASSESSMENT COMPLETE / REASSESS:
Reviewer, approver and date:

This module completes the bridge from procurement evidence to a site exposure screen; it does not turn an unsuitable supplier test into an exposure measurement. The site’s occupational-health process remains the Owner for worker exposure controls and legal compliance.

Variables that can change the measured result

An air-leg rock drill is a system rather than an isolated motor. The reported value can move when the test changes any of the following:

Feed thrust and alignment: insufficient or unstable support can allow the steel to bounce or the machine to chatter; excessive thrust can alter impact and rotation behaviour.
Air pressure at the inlet: pressure loss through a long or undersized hose can change the drill’s operating condition even when the compressor gauge appears correct.
Drill steel and bit condition: bent steel, a damaged shank, worn carbide or an unsuitable bit can make the test non-representative of a new, matched system.
Rock and hole stage: collaring, steady drilling and breakthrough are different events. A report should state which stage was measured and how transitions were handled.
Handle, control and leg configuration: small design or assembly differences can affect the operator interface. The supplied configuration must match the tested one.
Maintenance condition: lubrication, chuck-bushing wear, fastener condition and internal wear can change vibration and should be recorded before testing.

These variables are also why a buyer should request test evidence for the offered configuration rather than copy a catalogue value from another market or model family.

Recommended RFQ clause

Provide vibration measurement evidence for the offered air-leg rock drill and leg configuration. State the measurement method and edition, explain its applicability to leg-fed machines, and list all deviations. Identify the drill, air leg, handle, drill steel, bit, test medium, air pressure at the tool inlet, lubrication condition, sensor position, frequency weighting, axes, number of runs, result, uncertainty, laboratory, test date, report number and calibration status. Do not state compliance with ISO 28927-10 for a jackleg or push-feed configuration unless the claim is supported by the standard’s scope and a documented technical justification. Supplier data will be used for procurement screening and will not replace site exposure assessment.

Add the clause to the technical schedule, not only the purchase-order notes. Require the supplier to identify any configuration change made after testing. If the offered drill is only a reference configuration at quotation stage, make the final report a document-hold point before shipment.

Common procurement mistakes

Accepting a number without a method. Units alone do not make a result comparable.
Assuming every “rock drill” falls under the same test code. Machine support and feed arrangement determine whether a scope statement fits.
Comparing unlike accessories. Different legs, steels, bits or pressure conditions can overwhelm the model-to-model difference.
Treating emission as daily exposure. Actual exposure depends on task duration, work practice, rock, maintenance and other site conditions.
Ignoring uncertainty. Ranking close values without uncertainty creates false confidence.
Buying an “anti-vibration” claim without controlled evidence. Ask what changed, how it was tested and whether the tested configuration is the one being supplied.

Pre-purchase acceptance checklist

Offered drill and air-leg model are uniquely identified.
Claimed standard or method is applicable, or the limitation is explicitly documented.
Test configuration matches the quoted product, drill string and intended drilling direction.
Tool-inlet air pressure and lubrication condition are reported.
Sensor position, axes, weighting, run count and averaging method are stated.
Measured result is accompanied by uncertainty.
Report number, date, laboratory and calibration traceability are present.
Any prototype or special test component is disclosed.
Field-trial plan keeps the compared configurations and operating conditions controlled.
Site safety team will assess representative operator exposure separately.

Frequently asked questions

Does ISO 28927-10 apply to an air-leg or jackleg rock drill?

Not to the jackleg and push-feed configurations excluded in the standard’s published scope. If a supplier cites it, ask which exact machine configuration was tested and require a technical explanation of applicability and deviations.

Can two vibration values in m/s² be compared directly?

Only when the method, machine class, support, accessories, operating conditions, result definition and uncertainty are sufficiently equivalent. If those items differ, the numbers may describe different tests rather than a real product difference.

Is the lowest declared value automatically the best buying choice?

No. Evidence quality comes first. A low value from an incomplete or inapplicable method may be less useful than a well-documented result that can be reproduced and checked during a field trial.

Can a supplier report set an operator’s safe daily drilling time?

Not by itself. Daily exposure depends on the measured vibration in representative work and the time actually spent exposed, together with applicable local requirements and controls. Use competent site assessment for that decision.

What should a buyer do if no applicable standardized air-leg test is available?

Require a documented, repeatable method with clear limitations; keep configurations matched; request uncertainty and traceability; and validate shortlisted equipment in a controlled site trial. The report should state what it demonstrates and what it does not.

Specify the evidence before comparing the equipment

PerfoMax can help procurement teams match an air-leg drill configuration and organize the technical information needed for an RFQ. Review the active YT28 air-leg pneumatic rock drill, browse the rock drill range, or use our published guide on choosing an air-leg rock drill for underground mining. Send the intended drilling direction, hole range, drill steel, bit, air supply, leg configuration and required vibration evidence with your enquiry so the quotation can be checked against one controlled configuration.