You spent weeks choosing the insert and the grade, and then you aimed the coolant with whatever hose was already bolted to the turret. That hose is doing half the work of the cut, and nobody specified it. A modular coolant line is the cheapest part of the setup and the easiest one to get exactly right, because it is built from a handful of pieces that screw together by hand. Here is the whole system, in the order you would build one.
The system in a minute and a half, from the manufacturer.
What a jointed line actually is
A Hirt-Line hose is not a hose. It is a chain of short stainless steel elements, each with a ball on one end and a socket on the other, held together by a union nut you tighten by hand. Every joint is a ball joint, so the line bends wherever you want it and stays there.
That last part is the whole point. The reason a plastic segmented hose drifts out of position is that coolant pressure and spindle vibration slowly push it back. The manufacturer builds these in stainless and rates the system to 100 bar—about 1,450 psi—and states that neither coolant pressure nor machine vibration will move the aim once the nut is tight.
First decision: which of the four systems
There are four sizes, and they are not interchangeable. Pick by the flow you need, then stay in that family.
| System | Bore | Typical job | Parts we stock |
|---|---|---|---|
| Typ 0 (1/8") | 3.2 mm | Swiss-type, small part work, tight turret space | 25 |
| Typ 1 (1/4") | 5.8 mm | The default on most mills and lathes | 93 |
| Typ 2 (1/2") | 11 mm | High volume, grinding, roughing, flood over a wide zone | 67 |
| Typ 3 (3/4") | 19 mm | Large machines, washdown, chip flushing | 30 |
If you are between two, size up. A larger bore throttled by a smaller nozzle gives you flow in reserve; a small bore cannot be made bigger at the tip. And if you do need to cross families later, reductions exist: Typ 2 to Typ 1 and Typ 1 to Typ 0.
The five pieces every line is made of
Once you have the size, a line is always the same five things in the same order.
- An adapter at the machine end to match whatever thread the coolant manifold gives you.
- Basic elements—the straight links that make up the length.
- A junction, if the line needs to split or turn hard.
- A nozzle at the tip. This is the part that decides what the coolant actually does.
- A nut on every joint and a spanner if you want it tighter than hand tight.
Adapters: the piece people forget to order
The adapter is the only part that has to match something you did not choose. In the 1/4" system alone we stock straight threads in 1/8", 1/4", and 3/8"; tapered PT versions of the same; metric M10×1 and M14×1; and an 8L for hydraulic tube fittings.
Basic elements: length is a part number
Elements come in fixed lengths, and you chain them. In the 1/4" system: L19, L36, L54, L73, L100, and L300, in millimeters.
Short elements buy you articulation; long ones buy you reach with fewer joints. A line made entirely of L19 elements will curl into any shape you like and has a joint every 19 mm to leak from if you are careless. A line of two L300 elements and one short one at the tip is rigid where it should be and adjustable exactly where it matters.
Junctions: one feed, several targets
Elbows, T-pieces, Y-pieces, and a four-way star. There are rigid and flexible versions of most: the flexible ones articulate at the junction itself, and the rigid ones hold a fixed angle.
For a bigger split, the manifold block takes one 1/2" feed and gives three 3/8" outlets, with plugs for the outlets you are not using yet. That is how you feed three nozzles around one tool from a single port.
Nozzles: the part that does the work
Everything upstream just delivers pressure to this piece. The nozzle decides the shape of the stream, and that is what separates coolant that cools from coolant that splashes.
The 2-DU-10, a Ø10 mm round nozzle in the 1/2" system, is running. German narration, but the picture is the point.
| Nozzle | What it gives you | Use it when |
|---|---|---|
|
Round, straight Ø2.0 to Ø12 mm |
A single coherent jet that carries to a point | You need to reach one spot: a drill, a boring bar, or the cutting edge of a turning insert |
|
Flat / slot 18×2.5 up to 70×1.0 mm |
A wide sheet of coolant | Grinding wheels and face mills, where the zone is a line rather than a point |
|
90° 2× or 5× Ø2 mm |
Jets perpendicular to the line | There is no room to point the hose at the cut, only alongside it |
|
Multi-hole e.g., 9× Ø1.5 mm |
Several small jets covering an area | Washing chips out of a pocket, or soaking a zone rather than hitting a point |
|
Blank no hole |
Nothing, on purpose | Capping a branch so the pressure goes where you want it |
There are plastic versions of several nozzles—the KU prefix. They cost less, and they are the sensible choice where a nozzle gets knocked by a part or an operator and has to be treated as a consumable.
The pieces that make it a system instead of a hose
- Mini ball valves, including a stainless V2A version. Shut off one branch without shutting off the machine, so you can run a two-nozzle setup and use one of them.
- Quick coupling. Pull a whole prebuilt line off and put another on between jobs.
- Manual adjustment nut. A knurled nut you can set by hand when the line gets re-aimed often.
- Spanners—SW-11, SW-16, SW-19, SW-27. Hand tight holds; a spanner holds at pressure.
A multi-nozzle installation on a grinding machine, which is where the flat nozzles earn their keep.
Starting from zero: buy the set
If this is your first line, the basic set is the shortcut. It gives you an assortment of elements, a nozzle, and the fittings to get one line running, and after that you buy singles for what the next job needs.
0-GS for the 1/8" system, 1-GS for the 1/4", 2-GS for the 1/2", and 3-GS for the 3/4".
Questions we get
Which Hirt-Line system size do I need?
Match it to flow, not to the size of the machine. Typ 1 (1/4", 5.8 mm bore) covers most mills and lathes and is the one to default to. Typ 0 (1/8") is for Swiss-type and small part work where space is the constraint. Typ 2 (1/2") is for grinding, roughing, and anywhere you need real volume. Typ 3 (3/4") is for large machines and chip flushing. If you are between two, size up: you can always restrict flow at the nozzle.
My machine ports are NPT. Which adapter do I need?
Check whether the adapter is parallel or tapered, because the basic sets ship with the parallel one. Hirt-Line makes both: 2-AD-12 is parallel, 2-AD-12PT is tapered, and the same PT pairing exists across the sizes. Both are cut to the 55° British form rather than the 60° American one, and a parallel male thread will not seal in a tapered NPT port no matter how hard you pull on it.
What saves you is the pitch. At 1/2" and 3/4" the British taper and NPT both run 14 threads per inch, so the PT adapter engages an NPT port properly and seals with a thread sealant. At 1/4" and 3/8" they do not—NPT is 18 threads per inch against 19—so those will start, feel wrong, and never seal. Use a liquid thread sealant rather than PTFE tape: tape shreds, and the shreds end up in the coolant looking for the smallest nozzle you own. Tell us the port size and form, and we will confirm the part before you order.
Can I connect this to the Loc-Line hose I already have?
Yes. There is a Loc-Line adapter in the 1/4", 1/2", and 3/4" systems. A common way in is to leave the plastic hose on the machine and replace only the last stretch and the nozzle, which is the part that drifts out of aim and the part that decides the shape of the stream.
What pressure will it take?
The manufacturer rates the system at 100 bar, about 1,450 psi, and builds it in stainless steel. The relevant practical point is not the burst number but that at normal shop pressures the aim does not move: the joints are metal ball joints held by a union nut rather than friction between plastic segments.
Will this work on a low-pressure flood system?
Yes. The 100 bar figure is a ceiling, not a requirement. Most shop flood systems run somewhere between 10 and 30 psi, and the system is as much at home there as on a high-pressure pump. What changes is the variable you have to respect: at low pressure you are delivering volume rather than velocity, so the bore of the line and the open area of the nozzle matter more than the pressure gauge does. Size up rather than down—Typ 2 has an 11 mm bore against Typ 1's 5.8 mm—and keep the total nozzle opening inside what your pump can actually fill.
Round nozzle or flat nozzle?
Round for a point, flat for a line. A drill, a boring bar, or the nose of a turning insert is a point, so a round nozzle that keeps the jet coherent is what carries coolant there. A grinding wheel or a face mill is working along a line, and a flat nozzle lays a sheet across it. Using a round nozzle on a wide zone is how you end up with one wet spot and a hot cut.
Do I need the spanner, or is hand tight enough?
Hand tight assembles and holds the shape. Under pressure, a spanner is what stops a joint from weeping. They are inexpensive and sized per system: SW-11 and SW-16 for the smaller lines and SW-19 and SW-27 for the larger.
Can I run two nozzles from one coolant port?
Yes, and it is usually the better setup. Use a T-piece or Y-piece for two, the four-way star for three, or the manifold block if you want one 1/2" feed turned into three 3/8" outlets. Add a mini ball valve on a branch you do not always want running. One thing to plan for: a split divides the flow; it does not duplicate it. On a low-pressure system the nozzle at the cut will notice the moment the second branch opens, which is exactly why the valve belongs on the branch you run intermittently.
Can I use a spare coolant port for chip flushing?
That is one of the most common reasons a second line gets built. Plenty of machines have a bulkhead port nobody ever used, and a dedicated flush line off that port beats splitting the one feeding the cut, because it does not take flow away from the nozzle doing the cooling. Put a mini ball valve on it, and you can shut the flush off for a finishing pass without touching the machine's coolant settings.
The full range, all four systems and every component, is on the Hirt Line overview page. And if the question is where to aim the thing once it is built, Thursday's TechTips takes that up.
Browse the Hirt Line systems. →
Component names, sizes, and system bores in this article are taken from the Hirt-Line range as stocked by FM Carbide. The 100 bar pressure rating and the stainless construction are the manufacturer's stated specifications. Videos are from the Hirt-Line manufacturer's own channel; several are narrated in German and are included for what they show. Tell us the machine, the port thread, and the operation, and we will put the line together for you.
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