Direct answer: a pneumatic rock drill water hose is compatible only when the complete connection matches the drill—not merely when the hose looks close in size. Confirm the exact drill model and manual, water-inlet thread, fitting gender, sealing method, hose inside diameter (ID), working-pressure rating, line length, and water-supply pressure at the tool. A hose can screw onto an adapter and still be wrong if the thread form, sealing seat, bore, or pressure envelope does not match.
For YT28-class air-leg drills, many references show a water hose around 12–13 mm ID, but that is a useful screening clue rather than a universal purchasing specification. The PerfoMax YT28 page therefore requires the selected hose and water connection to be confirmed on the quotation and supplier data sheet. This guide explains how maintenance teams, contractors, and buyers can make that confirmation before ordering a replacement line.
What must match on a pneumatic rock drill water hose?
Treat the water line as a small system with five interfaces. All five must pass before the hose is accepted.
| Compatibility point | What to verify | What a mismatch can cause |
|---|---|---|
| Rock drill identity | Manufacturer, exact model, revision, and water-inlet location | Ordering a hose for a visually similar but different drill |
| Inlet connection | Thread family, nominal size, pitch, gender, seat, and required seal | Cross-threading, leakage, a false “tight” condition, or cracked fittings |
| Hose bore | Actual inside diameter and the minimum bore through fittings | Restricted flushing, unstable flow, or unnecessary bulk and weight |
| Pressure envelope | Required pressure at the running drill and hose working-pressure rating | Poor flushing, internal backflow risk, hose damage, or unsafe failure |
| Installation | Length, bend radius, abrasion protection, restraint, cleanliness, and shutoff | Kinks, contamination, snagging, premature wear, or uncontrolled discharge |
Start with the exact drill model and controlled document
Do not select a water hose from “YT-type,” “jackleg,” or “air-leg drill” alone. Similar drills can use different inlet hardware or locally fitted adapters. Record the nameplate model, photograph the inlet from two angles, and obtain the current operator manual or supplier drawing. If the drill has already been modified, record the adapter as a separate component rather than assuming it is original.
The current PerfoMax YT28 air-leg pneumatic rock drill page identifies the hose and water connection as configuration items to confirm before quotation. Its listed 34–42 mm hole range and H22 × 108 shank are product references; they do not define the water fitting. The written quotation and attached data sheet should control the delivered connection.
How to identify the inlet thread and sealing method
A nominal pipe size is not a complete thread specification. Two fittings may have similar outside diameters yet use different thread standards, pitches, tapers, or sealing faces. Before choosing an adapter, verify:
- whether the drill inlet is male or female;
- the thread family stated by the manual or drawing, such as a BSP or NPT designation where applicable;
- whether the thread is parallel or tapered;
- the pitch or threads per inch;
- whether sealing occurs on the thread, a cone, a flat washer, an O-ring, or another seat; and
- the available engagement length without bottoming against an internal shoulder.
Use a thread-pitch gauge and caliper only as identification aids. A caliper reading cannot by itself distinguish every thread form. If the inlet is worn, corroded, painted, or damaged, compare it with a known sample or controlled drawing. Never force an uncertain adapter to “prove” compatibility: a few partially engaged turns can damage the inlet body.
Do not stack adapters to solve an unknown connection
Multiple reducers can create a narrow internal passage, extra leak points, and a long lever arm that loads the drill inlet when the hose moves. One correctly specified adapter is preferable. If conversion is necessary, document the drill-side thread, hose-side connection, minimum through-bore, material, pressure rating, and sealing method.
Hose ID, fitting bore, and length must be considered together
The hose inside diameter controls the available flow area; the outside diameter mainly reflects the wall and reinforcement. Procurement descriptions that state only “half-inch hose” can be ambiguous, because the label may refer to a nominal family rather than a measured bore. Ask for the actual hose ID in millimetres and confirm the smallest bore through every tail, nipple, valve, filter, and quick coupling.
Several YT-class and comparable jackleg references list water hoses around 12–13 mm ID. Other drills and connection packages differ. Use the value from the exact model’s manual, then maintain that bore through the assembled line unless the manufacturer authorizes a change.
Longer hose, tight bends, small fittings, partially closed valves, and loaded strainers all increase pressure loss. That means a correct tank or manifold reading does not guarantee correct pressure at a running drill. When the installation is long or shared among several drills, check pressure near the tool under flow—not only with the outlet closed.
Match water pressure to the drill—not to a generic rule
Water pressure must be high enough to deliver stable flushing at the bit, yet remain within the drill manufacturer’s operating envelope. The Secoroc YT28 operator instructions use about 3 bar water pressure and 5 bar air pressure at the tool as model-specific references. Those figures should not be transferred automatically to another rock drill.
Many pneumatic drill instructions also require water pressure to remain below the working air pressure so water cannot be driven backward into the pneumatic mechanism. Follow the exact start-and-stop sequence in the supplied manual. A common YT28 instruction is to establish the air supply before water and shut off water before air; the purpose is to reduce backflow into the drill. If the site uses a pump, pressure booster, elevated tank, or fluctuating mine-water main, add appropriate regulation and verify pressure while drilling.
The hose assembly’s working-pressure rating must exceed the maximum pressure it can actually see, including pump shutoff pressure and pressure spikes—not just the normal gauge reading. Confirm the rating for the assembled hose, crimp, adapters, valve, and coupling. The lowest-rated component governs.
Choose fittings and hose construction for the work environment
A technically matched bore and thread can still fail early if the hose is unsuitable for the site. Review:
- Abrasion: protect the line where it drags over broken rock, rails, or sharp steel edges.
- Flexibility: the hose must follow drill and air-leg movement without kinking at the tail.
- Bend radius: keep the first bend away from the fitting and follow the hose maker’s limit.
- Temperature: check cold-weather flexibility and the freezing risk in stopped lines.
- Water quality: select lining and fittings compatible with the site water.
- End retention: use an approved crimp or manufacturer-specified tail and clamp arrangement.
- Restraint and routing: prevent whipping, snagging, crushing, and contact with moving controls.
Do not select the water hose by copying the larger compressed-air hose. The two lines have different duties, bore requirements, fittings, and pressure-control roles. Mark or route them so crews cannot interchange them during setup.
Water cleanliness is a compatibility requirement
Flushing passages are small enough that rust flakes, scale, sand, sealing-tape fragments, or hose-cutting debris can restrict flow. Clean the supply, flush a new hose before connecting it, and keep protective caps on open ports. A strainer may be appropriate where the approved system requires it, but its element and clean pressure loss must not starve the drill.
After fitting a new line, verify that flow reaches the drill steel and bit without abnormal leakage. If flow remains weak after the external hose, regulator, and fittings pass inspection, use the published YT28 water-flushing troubleshooting guide to check internal items such as the water needle and passages. Do not compensate for an internal restriction by raising water pressure beyond the manual limit.
Replacement measurement workflow
- Isolate energy. Shut off, depressurize, and drain the air and water lines before disconnecting fittings.
- Identify the drill. Record manufacturer, model, serial or revision where available, and existing adapter details.
- Photograph before removal. Capture the inlet, fitting stack, hose routing, valve, and restraint.
- Inspect the inlet. Clean it and check for crossed threads, corrosion, cracks, or a damaged sealing face.
- Measure and identify. Record thread gender, major diameter, pitch, engagement length, and seat style.
- Measure the flow path. Confirm hose ID and the minimum bore through every fitting.
- Confirm pressure data. Use the drill manual for required pressure and the hose maker’s data for working and burst ratings.
- Confirm length and routing. Allow full air-leg travel and drill positioning without tension, loops that snag, or bends below the permitted radius.
- Flush the line. Remove manufacturing debris before connecting it to the drill.
- Test safely. Pressurize gradually, inspect for leaks, and verify water flow at the tool under operating conditions.
Common purchasing mistakes
- Ordering by model family only: the drill or adapter may differ from the assumed configuration.
- Using outside diameter as hose size: OD does not establish the available water bore.
- Calling any similar pipe thread “half-inch”: nominal size does not define thread family or seal.
- Checking static pressure only: restrictions may appear only while water is flowing.
- Ignoring fitting bore: a small adapter can cancel the benefit of a correctly sized hose.
- Raising pressure to overcome blockage: this can create backflow or damage instead of fixing the restriction.
- Reusing damaged clamps or tails: leakage and hose separation risks remain even when the new hose is correct.
- Leaving the hose unprotected: abrasion, kinking, and snagging shorten service life and create hazards.
What to include in an RFQ for the water-hose package
- rock drill manufacturer, exact model, and revision;
- photo of the nameplate, inlet, existing fitting, and hose end;
- drill-side thread, gender, pitch, sealing seat, and engagement length;
- required hose ID, length, material, reinforcement, and minimum bend radius;
- working water pressure at the tool and maximum possible supply pressure;
- fitting material, minimum through-bore, crimp or clamp method, and restraint;
- water source, temperature range, contamination risk, and any regulator or strainer;
- quantity, spare ratio, marking, inspection documents, and packing needs; and
- the controlled drawing or data-sheet revision that will govern acceptance.
FAQs about pneumatic rock drill water hoses
Is a 13 mm water hose correct for every YT28 rock drill?
No. Around 13 mm ID appears in several YT-class references, but the approved manual, supplied adapter, and quotation must control. Confirm actual ID, inlet thread, and fitting bore for the specific drill.
Can a BSP fitting be replaced with an NPT fitting of the same nominal size?
Not by assumption. The thread form, pitch, taper, and sealing method can differ. A partly engaged connection is not proof of compatibility and can damage the inlet.
Should water pressure equal compressed-air pressure?
Follow the drill manual. Many pneumatic drills require water pressure below working air pressure to reduce backflow risk. The Secoroc YT28 reference uses about 3 bar water and 5 bar air at the tool, but other models can specify different values.
Why is flushing weak with a new hose?
Check the valve, regulator, strainer, hose ID, fitting bore, kinks, line length, and pressure under flow. If the external line passes, inspect the drill’s internal water path rather than increasing pressure beyond the approved limit.
Can a quick coupling be added to make hose changes faster?
Only if its thread, seal, working-pressure rating, minimum bore, locking security, and contamination protection suit the approved system. A small or poorly secured coupling can restrict flow or disconnect unexpectedly.
Specify the complete connection before ordering
The most reliable replacement request is not “one YT28 water hose.” It is a controlled hose assembly tied to a specific rock drill, inlet, bore, pressure envelope, length, and installation. Send PerfoMax photos of the drill nameplate, water inlet, existing hose ends, and the required line length. The team can then review the connection alongside the active YT28 rock drill configuration and return the correct quotation basis.
Technical references consulted: Atlas Copco Secoroc YT28 operator instructions for model-specific air/water pressure and operating sequence; Ingersoll Rand YT28 product information for the current YT28 reference context; and manufacturer technical pages for comparable jackleg drill connection and hose examples. Always use the supplied manual and approved quotation for the final configuration.