In short: choose a 4-inch or 5-inch DTH hammer by matching the target hole diameter, the exact hammer model’s published bit range, and the compressor’s delivered flow at the required operating pressure. Do not choose from nominal hammer size alone. A 4-inch and a 5-inch hammer can overlap around some hole diameters, but their bit shanks, top-sub threads, air demand, drill-pipe requirements, and rig capability may be different.
This guide is for quarry and mine contractors, water-well drillers, distributors, and industrial buyers comparing 4-inch and 5-inch down-the-hole hammer systems before an RFQ. It focuses on the practical variables that decide whether the selected hammer can drill the required hole efficiently with the air and drill string actually available on site.
Selection rule: start with the finished hole diameter, check the manufacturer’s approved bit range for the exact hammer, then verify air supply, shank, top-sub thread, drill pipe, rig torque/feed, and ground conditions as one system.
Why 4-Inch and 5-Inch DTH Hammer Ranges Overlap
Nominal hammer size is a useful class label, but it is not a universal hole-size limit. The bit must be larger than the hammer body so compressed air and cuttings can return through the annular space between the hammer and borehole wall. If the hole is too tight for the hammer body, airflow around the tool is restricted. If the hole is much larger than the intended production range, flushing efficiency and drilling economics can deteriorate.
OEM data shows the overlap clearly. Mincon currently lists its 4-inch MP-series hammers for 110–130 mm holes and its 5-inch MP-series for 127–152 mm holes. Epiroc lists COP 44 Gold at 110–130 mm and COP 54 Gold at 134–152 mm, while the COP 54 Gold Slim extends the 5-inch-class example down to 127 mm. These are manufacturer- and model-specific ranges, not values that should be copied across brands.
The buying implication is important: a 127–130 mm hole can fall near the upper end of some 4-inch hammer ranges and the lower end of some 5-inch ranges. In that overlap, the better choice depends on the exact hammer, available compressed air, rig configuration, bit/shank system, desired production rate, and operating conditions.
4-Inch vs 5-Inch DTH Hammer: Buyer Comparison
| Decision point | 4-inch class | 5-inch class | What to verify |
|---|---|---|---|
| Typical hole-size role | Commonly used for smaller production holes within the model’s published bit range | Used when the required hole moves into a larger bit range or when the selected system is designed around a 5-inch hammer | Exact hammer data sheet, not a generic inch-size chart |
| Air requirement | Usually lower than a comparable larger hammer, but rises with pressure and model design | Usually requires greater delivered airflow; compressor suitability becomes more critical | Hammer air consumption at intended pressure and field compressor output |
| Bit shank | Uses the shank specified by the 4-inch hammer | Uses the shank specified by the 5-inch hammer | Shank drawing, chuck/retainer, foot-valve or tubeless configuration where applicable |
| Top-sub thread | Often paired with smaller drill-pipe connections, depending on model | Often uses larger connections, depending on model | Hammer top sub and drill-pipe thread must match or use an approved adapter |
| Rig requirement | Can suit compact DTH rigs where torque, feed and air package are sized accordingly | Requires confirmation that rig rotation, feed, handling and air package support the larger system | Rig model and manufacturer-approved DTH configuration |
Step 1: Define the Finished Hole Diameter First
The blast design, water-well program, foundation design, or other drilling requirement should define the finished hole diameter. That dimension sets the first physical boundary for hammer selection.
Do not begin with “we want a 5-inch hammer.” Begin with “we need a 127 mm finished hole” or “we need 140–152 mm production holes.” Then compare the required diameter with the exact hammer and bit combination offered by the supplier.
For example, Epiroc’s current product data places COP 44 Gold in a 110–130 mm recommended range and COP 54 Gold in a 134–152 mm range, with COP 54 Gold Slim at 127–152 mm. Mincon’s current 4-inch family spans 110–130 mm, while its 5-inch family spans 127–152 mm. The overlap reinforces why the model data sheet is the final authority.
Step 2: Check the Compressor at Working Pressure, Not by Nameplate CFM Alone
A DTH hammer is an air motor and impact system at the bottom of the hole. Compressed air drives the piston and then exits through the bit to flush cuttings. The compressor therefore has to supply the hammer’s required airflow at the intended operating pressure, after real system losses.
Before ordering, verify:
- hammer air consumption at the planned pressure;
- compressor free-air delivery at that pressure, not only a maximum-flow headline;
- hose and drill-pipe internal diameter;
- line length, couplings, swivel and other restrictions;
- altitude and ambient conditions where they materially affect compressor output;
- other pneumatic consumers operating simultaneously;
- water injection or other flushing conditions required by the job.
Do not convert a generic “4-inch hammer” or “5-inch hammer” label directly into one universal CFM requirement. Different hammer designs consume different amounts of air, and consumption changes with pressure. Use the specific hammer curve or current manufacturer specification.
Epiroc’s surface-rig range illustrates the system relationship. Its PowerROC D45 is configured around 4-inch DTH drilling for 90–130 mm holes, while larger D55 and D60 configurations cover broader hole and hammer ranges with larger installed air packages. Those rig air-capacity figures should not be treated as hammer-consumption values; they simply show that the rig, compressor, hammer class, and hole range are engineered together.
Step 3: Match the Bit Shank and Top-Sub Thread
A hole diameter match does not make the bit compatible with the hammer. The bit shank must match the hammer chuck and retaining system exactly. The top sub must also match the drill pipe or a verified adapter arrangement.
When moving from a 4-inch to a 5-inch hammer, buyers often discover that the change affects more than the hammer body. The bit shank, top-sub thread, drill-pipe diameter, breakout tooling, spare parts, and sometimes the rig handling setup can all change.
For mixed-brand or replacement purchases, send the supplier:
- current hammer brand and model;
- bit shank designation or drawing;
- top-sub thread;
- drill-pipe outside diameter and thread;
- photos and measurements if part numbers are unavailable.
PerfoMax Example: CIR90 vs CIR110
PerfoMax currently lists two models that show how a 4-inch-to-5-inch comparison should be handled as a complete system rather than by nominal size alone.
| Current PerfoMax model | CIR90 | CIR110 |
|---|---|---|
| Nominal class | 4-inch class | 5-inch class |
| Current listed hole range | 105–130 mm | 120–165 mm |
| Current listed pressure range | 10–25 bar | 18–25 bar |
| Current listed air requirement | Approximately 8–20 m³/min depending on pressure; the product page recommends checking compressor output for the intended operating point | PerfoMax currently specifies a larger air package and lists approximately 25 m³/min as the comparison requirement |
| Bit shank / system note | DHD340 / CIR90-class interface | CIR110-class interface; not interchangeable with CIR90 bits |
| Top-sub connection | API 2-3/8 Reg or API 2-7/8 Reg configurations are currently listed | API 2-7/8 Reg or API 3-1/2 Reg configurations are currently listed |
The ranges overlap between 120 and 130 mm, but that does not mean the two systems are equivalent there. For a buyer already operating a CIR90-compatible bit and pipe system with adequate air, the 4-inch configuration may remain the lowest-change option within its approved range. For a larger target hole or a fleet designed around the CIR110-class string, the 5-inch system may be the more appropriate starting point. Final configuration should be confirmed in the quotation and technical agreement.
Review the PerfoMax CIR90 DTH Hammer, CIR110 DTH Hammer, or the broader DTH Hammer Selection Guide for the current product data.
Step 4: Check Drill Pipe and Annular Clearance
The hammer, pipe, and borehole form the cuttings-return path. The drill pipe must carry the required compressed air without excessive restriction while leaving enough annular space for cuttings to travel back to surface. Poor hole cleaning can reduce penetration, recuttings, increase wear, and contribute to sticking.
Do not select pipe only from the top-sub thread. Confirm pipe outside diameter, inside air passage, wall section, thread, length, straightness, and rig handling. PerfoMax currently offers 76 mm DTH drill pipe with API 2-3/8 Reg thread for compatible configurations, but that product should only be paired with a hammer whose selected top sub is verified to match.
Step 5: Use Rock and Application as Confirmation Variables
Hole diameter and air supply define whether the system is physically viable; rock and application refine the choice. Hardness, abrasiveness, fracturing, water, hole depth, inclination, and production target affect bit face, button configuration, operating settings, wear, and economics.
A larger hammer is not automatically better in harder rock. If a 5-inch hammer forces the rig beyond its practical air or handling capacity, the nominal increase in impact potential may not produce a better drilling result. Conversely, pushing a smaller hammer at the extreme end of its approved hole range may be uneconomic in a high-production application. Compare the full system and actual field objective.
Common 4-Inch vs 5-Inch DTH Selection Mistakes
- Choosing from nominal inch size only: published hole ranges overlap and vary by model.
- Using hole diameter as the only variable: the compressor, shank, thread, pipe and rig still have to match.
- Using compressor nameplate flow without pressure: air consumption must be checked at the intended operating pressure.
- Treating rig air capacity as hammer consumption: rig specifications describe the complete machine, not the isolated hammer’s air curve.
- Assuming 4-inch and 5-inch bits interchange: different hammer classes often use different shank systems.
- Ignoring pipe and annular clearance: a system that impacts well but cannot evacuate cuttings will not drill efficiently.
- Ordering before verifying the installed system: a photo of the hammer, bit shank, top sub, and pipe thread can prevent an expensive mismatch.
RFQ Checklist: What to Send Before Selecting the Hammer Size
For a faster and more reliable technical recommendation, include:
- target finished hole diameter and acceptable range;
- typical and maximum hole depth;
- application: quarry blast hole, mine production, water well, foundation, geothermal, or other;
- rock type, abrasiveness, fractures, water and current drilling problems;
- drill rig make/model and rotation/feed capability;
- compressor make/model, rated flow at operating pressure, and working pressure used on site;
- altitude if materially different from the compressor’s standard rating condition;
- current hammer model and bit shank if replacing an installed system;
- drill-pipe outside diameter, thread and length;
- required quantity, destination and preferred commercial terms.
You can also browse the current DTH Tools collection, then send an RFQ with the known system details.
Frequently Asked Questions
Can a 4-inch DTH hammer drill a 5-inch hole?
Some 4-inch-class hammers are published for holes near 5 inches, but the exact model determines the limit. Mincon currently lists its 4-inch MP-series at 110–130 mm, and Epiroc lists COP 44 Gold at 110–130 mm. Do not apply those ranges to another hammer without checking its current data sheet.
When should I move from a 4-inch to a 5-inch DTH hammer?
Consider the 5-inch class when the required hole is outside the 4-inch model’s approved range, when the selected 5-inch system gives a better fit to the production objective, or when the rig and drill string are already designed around that class. The compressor must also supply the larger hammer at its required pressure and flow.
Does a 5-inch DTH hammer always drill faster than a 4-inch hammer?
No. Penetration depends on the complete drilling system, including available air, pressure, bit and shank design, rock, rotation, feed, flushing, wear, and hole size. A larger hammer that is under-supplied with air can perform worse than a correctly matched smaller system.
Can I size the compressor from hammer inch size alone?
No. Use the exact hammer manufacturer’s air-consumption data at the intended operating pressure. Then check whether the compressor can deliver that flow under actual site conditions after hose, pipe, altitude, and simultaneous-air-use effects are considered.
What is the most important information to include in a DTH hammer RFQ?
Start with hole diameter and depth, rig model, compressor flow and pressure, current hammer/bit shank, drill-pipe thread, rock condition, and application. Those inputs allow the supplier to verify the hammer, bit, pipe, and air system together instead of guessing from nominal size.
Technical References
- Epiroc — COP Gold Series: model-specific recommended hole ranges
- Epiroc — Surface DTH drill rigs: hammer, hole-range and installed-air examples
- Mincon — 4-inch DTH hammer range
- Mincon — 5-inch DTH hammer range
Last reviewed: August 11, 2026. Hole ranges, air requirements, connection options and product availability are model-specific and can change. Verify the current hammer data sheet, rig documentation, and supplier quotation before purchase or system modification.