Route: /engineering-tools/dth-hammer-duty-comparison-tool/ (proposed until route reconciliation).

1. Purpose and Engineering Decision

A DTH hammer should be compared using the exact equipment identity and the pressure-flow duty supplied by the hammer manufacturer or other accepted technical source. Pressure and airflow must remain paired. A compressor with more nominal CFM is not automatically suitable if that flow is unavailable at the hammer's required working pressure.

Comparison mode	Primary result
Hammer vs hammer	Pressure-flow evidence and configuration differences
Hammer vs compressor	Duty coverage at the same pressure
Multiple operating cases	Minimum / normal / maximum documented duty
Alternative bit / shank	Change-control warning and revalidation
Evidence audit	PASS / HOLD / FAIL with reason trace

2. Required Asset - Hammer Duty Evidence Comparison Worksheet

Field	Hammer A	Hammer B / alternative	Evidence requirement
Manufacturer / model	Enter	Enter	Exact identity
Hammer variant / generation	Enter	Enter	Do not infer from family name
Bit diameter	Enter	Enter	Actual or intended
Shank type	Enter	Enter	Exact designation
Working pressure	Enter	Enter	Documented pressure
Air consumption	Enter	Enter	Documented flow
Flow basis	FAD / SCFM / actual / other	Same	Must be defined
Operating case	Min / normal / max	Same	Source-specific
Source document	Manual / catalogue / letter	Same	Title + revision/page
Qualification	Notes	Notes	Site/rig restrictions
Decision	PASS/HOLD/FAIL	PASS/HOLD/FAIL	Reason required

3. Keep Pressure and Flow Together

Hammer Duty = (Required Pressure, Required Airflow, Defined Flow Basis, Defined Configuration)

The pair must not be separated. A hammer requirement of 'X m3/min' without its corresponding pressure is incomplete, and a maximum hammer pressure without air-consumption evidence is equally incomplete.

4. Compressor Candidate Must Be Compared at the Same Pressure

Duty Margin_flow = Q_compressor,available_at_required_pressure - Q_hammer,required

Duty Margin_pressure = P_compressor_supported - P_hammer,required

The available compressor flow should come from a model-specific performance table, not the largest flow shown elsewhere in the brochure.

5. Source-Backed Portable Compressor Evidence Examples

The uploaded portable-compressor brochures demonstrate why pressure-flow pairing matters. These are compressor examples only, not hammer requirements.

Candidate example	7 bar	10 bar	12 bar	14/15 bar	Source note
M81 / M82	8.4 m3/min	6.8 m3/min	6.1 m3/min	5.5 m3/min @14 bar	Model-specific technical table
M31E	3.15 m3/min	2.6 m3/min	2.3 m3/min	1.9 m3/min @14 bar	Electric portable technical table
M13 / M13E	1.20 m3/min	1.00 m3/min	0.90 m3/min	0.75 m3/min @15 bar (M13E)	Small portable technical table
M50	5.0 m3/min	Not shown in supplied M50 table	Not shown	Not shown	Do not invent intermediate points

This comparison table is intentionally literal. If a pressure point is not published in the supplied source, the worksheet leaves it unavailable instead of interpolating silently.

6. Exact Hammer Identity

A similarly named hammer, a different generation or an undocumented rebuild must not inherit another tool's published duty automatically.

7. Operating Case Register

Case	Use	Rule
Minimum documented duty	Lower supported operating point	Do not call this normal duty unless source says so
Normal / recommended duty	Primary comparison case	Preferred selection anchor
Maximum documented duty	Upper supported case	Check compressor envelope and rig limitations
Special condition	Water, deep hole, flushing, alternative bit	Keep separate until source defines requirement

8. Flow Basis

Hammer documents and compressor brochures may use different flow conventions. No conversion is made if the source state is unknown.

Flow statement	Treatment
m3/min FAD	Use as reference flow after basis confirmation
SCFM / Nm3/h	Normalize to common reference basis
Actual flow at pressure	Convert only with pressure and temperature state
Unlabelled CFM	HOLD until source basis is established

9. Pressure Basis

Working pressure may be shown as bar(g), bar(a), psi(g) or another basis. A pressure unit conversion does not create missing hammer performance data.

10. Compressor Evidence Register

Candidate	Required fields before PASS
Portable compressor	Model, pressure version, available flow at required pressure, reference basis, ambient/altitude qualification
Booster-assisted package	Primary compressor duty, booster inlet requirement, booster flow/pressure envelope, interstage losses
Rental package	Exact supplied model/configuration, hose/manifold arrangement, accessories and site derating basis

11. Site Qualification Before Final Acceptance

Factor	Why it matters
Altitude	Lower inlet density can affect compressor/engine capability
Ambient temperature	Can affect cooling and available performance
Hose / drill-string loss	Reduces pressure available at hammer
Leakage	Reduces flow delivered to the tool
Water / groundwater condition	May change flushing and operating behaviour
Simultaneous air users	Hammer-only duty may not equal total compressor duty
Rig limitations	Connections, swivel, drill string and controls can constrain usable duty

12. Worked Validation Case A - Pressure-Flow Pairing

Synthetic calculator test: Hammer requirement is entered as 6.0 m3/min at 12 bar on a confirmed common reference-flow basis. Candidate X is documented at 8.4 m3/min at 7 bar but 6.1 m3/min at 12 bar.

Flow margin at 12 bar = 6.1 - 6.0 = +0.1 m3/min

The tool compares 6.1 m3/min, not the 8.4 m3/min headline flow. The result may be technically close and should remain subject to site loss, derating and reserve review.

13. Worked Validation Case B - Higher Flow at Wrong Pressure

Synthetic calculator test: Hammer duty is 6.2 m3/min at 12 bar. Candidate Y can provide 7.0 m3/min, but only at 7 bar, with no published 12 bar operating point.

A higher low-pressure CFM value does not prove high-pressure suitability.

14. Worked Validation Case C - Missing Hammer Source Basis

Synthetic calculator test: an enquiry says 'hammer requires 350 CFM' but provides no model, pressure or flow basis.

Required action: obtain hammer identity, applicable manual/catalogue entry, pressure, airflow and basis before compressor acceptance.

15. Worked Validation Case D - Alternative Hammer

Synthetic calculator test: the rig changes from Hammer A to Hammer B after mobilisation. The two hammers share nominal size but have different shank and published duty.

Nominal size similarity is not accepted as evidence that the original compressor duty remains valid.

16. PASS / HOLD / FAIL Logic

Status	Meaning
PASS - evidence coverage	Required pressure-flow pair is covered by model-specific compressor data and qualifications are accepted
HOLD - information gap	One or more governing inputs are missing, mismatched or unverified
FAIL - duty not covered	Documented compressor capability does not meet the required pressure-flow pair

PASS means the documented air-supply duty is covered. It does not guarantee penetration rate, completed depth, water yield or project duration.

17. Margin Policy

Any reserve allowance must have a stated reason: site uncertainty, leakage, line losses, future demand, simultaneous users or a project-specific acceptance rule.

18. Link to Annular Velocity

A satisfactory hammer-flow comparison does not by itself prove cuttings transport.

19. Input Model

Input group	Field	Validation
Hammer	Manufacturer/model/variant	Required
Tooling	Bit diameter + shank	Required
Duty	Pressure	Required
Duty	Airflow + basis	Required
Evidence	Document title/revision/page	Required for final PASS
Compressor	Model / pressure version	Required
Compressor	Available flow at required pressure	Required
Site	Altitude / ambient / losses	Explicitly accepted or unresolved
Decision	PASS/HOLD/FAIL + reason	Required

20. Validation and Guardrails

Condition	Required behaviour
Hammer model missing	HOLD
Pressure missing	HOLD
Flow basis missing	HOLD
Candidate flow taken from different pressure	Block comparison
Unsupported interpolation between compressor points	Block unless supplier method explicitly permits
Hammer-only duty used as total project demand	Warn and require other users/losses review
Alternative hammer or bit introduced	Invalidate prior acceptance until rechecked
PASS used as drilling-performance guarantee	Show limitation warning

DTH Hammer Duty Comparison Tool

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