Helical coil nylon pipe overview
A helical coil nylon pipe is a PA12 tube coiled at the factory for oil-air and MQL lubrication lines. When the system stops, oil settles into the lower loops as a small reservoir; on restart, the airflow carries that oil to the bearing at once, so the point does not start dry.
This page covers the coiled reservoir tube only; straight runs belong to straight nylon tube, and the atomizing hardware to the MQL trace lubrication cooling system.
How the coil prevents dry starts
At standstill, gravity pulls oil into the bottom loops, leaving about 0.5 – 1.5 mL. On restart, airflow at typically 2 – 6 bar pushes this oil to the point first, covering the first 30 – 60 seconds. The coil also damps pressure pulses while the system runs.
Specification
| Material | PA12 standard; PA11 optional (-40°C to +100°C) |
| Outside diameter | 4.0 mm standard; 6.0 mm and 8.0 mm on request |
| Inside diameter | 2.0 mm (4 x 1.0 mm wall); 2.3 mm (4 x 0.85 mm wall, light) |
| Working pressure | up to 20 bar (290 psi) at +20°C; derate 1% per 1°C above +60°C |
| Burst pressure | 60 bar minimum (PA11 heavy-duty 80 bar minimum); a 3:1 burst-to-working ratio |
| Temperature (PA12, oil service) | -40°C to +80°C |
| Coil count | typically 3 – 7; 3 – 5 for standard oil-mist systems; 5 – 7 for feed lines over 2 m |
| Bend radius, 4 mm tube | about 15 mm static / 25 mm dynamic |
| Tube hardness | Shore D 60 – 65 |
| Compatible media | mineral oil, synthetic ester oils, fatty alcohols (MQL oils), NLGI 000 – 0 fluid grease |
| Not compatible | water-glycol, phosphate ester, concentrated acids and alkalis, ketones |
| Supply form | 50 m and 100 m coils; natural, blue, black, red |
Sizing the coil
The 4.0 mm OD covers most oil-air bearing lines; 6.0 mm and 8.0 mm are on request for higher flow. Standard oil-mist systems run on 3 – 5 coils; feed lines over 2 m take 5 – 7 coils so the reservoir matches the longer refill distance. Coil diameter and pitch can be customized.
Installation notes
Mount vertically or near vertically, oil inlet at the top; horizontal mounting sharply reduces the reservoir effect. Place the coil within 0.5 – 1.0 m of the point, with a 100 – 200 mm straight tube from outlet to bearing. Keep the natural pitch and clamp at 150 – 200 mm spacing.
Fittings and line checks
Pair the tube with 24° cone compression fittings or 4 mm push-to-connect line fittings; barbed fittings stop at 10 bar. At standstill, the lower 2 – 3 coils should show a visible oil film. Flush before switching oil type so residues cannot sludge the 2.0 mm bore. Straight sections use 4 mm nylon pipe.
Honest limitations
- The coil is a passive reservoir, not a metering device or accumulator; restart behavior also depends on coil volume, orientation, oil viscosity, line routing, and the check valve.
- The rating is 20 bar at +20°C, derated 1% per 1°C above +60°C; check high-temperature or pressure-shock duty first, and barbed fittings stop at 10 bar.
- Water-glycol, phosphate ester, concentrated acids and alkalis, and ketones must not enter the tube; flush before changing oil type or sludge can block the 2.0 mm bore.
Where it is used and how to order
Typical placements are CNC spindle bearings, ball screw nuts, and linear guide carriages on machines with frequent start-stop cycles, plus oil-mist lines on high-speed grinding and milling spindles and on textile, printing, and packaging machinery. For outdoor runs, choose black UV-stabilized PA12 or PA11, routed inside a guard. Send line length, oil type, and point count through the inquiry form to confirm sizing.
Frequently Asked Questions
Helical coil or straight nylon tube: which one do I need?
Pick the coil where frequent start-stop risks dry starts, or where the tube follows moving parts; pick straight tube for fixed runs with budgeted volume and pressure drop. Many lines use both.
How many coils should the helix have?
Three to five coils suit a standard oil-mist system; feed lines longer than 2 m call for five to seven. More coils add air resistance without adding useful reserve.
Should I choose 4 mm, 6 mm, or 8 mm tube?
The 4.0 mm OD standard covers most oil-air bearing duties; 6.0 mm and 8.0 mm are on request for higher flow or multi-point lines.
Where is the best mounting position?
Vertical or near vertical, inlet at the top, within 0.5 – 1.0 m of the point, with a 100 – 200 mm straight tube to the bearing; horizontal mounting loses most of the reservoir effect.
How can I tell the reservoir is working?
At standstill, look for an oil film in the lower two to three coils; after restart, mist should reach the point within seconds, with no bearing temperature spike.
Which fittings work with this tube?
Use 24° cone compression fittings or 4 mm push-to-connect fittings; Shore D 60 – 65 tube hardness suits both. Barbed fittings stop at 10 bar.
Can the tube carry synthetic ester or other MQL oils?
Mineral oil, synthetic ester oils, fatty alcohols, and NLGI 000 – 0 fluid grease suit PA12; PA11 gives a wider chemical margin. Water-glycol, phosphate ester, strong acids and alkalis, and ketones do not.
Can the coil be used outdoors?
Natural and blue PA12 turn brittle under long UV exposure; outdoors, specify black UV-stabilized PA12 or PA11 and still protect the tube with a sheath or enclosure.
What if the coil loses its shape?
Replace it. Creep under sustained load or tight bending pulls the pitch out of shape and shrinks the reservoir. Keep the natural pitch, clamp at 150 – 200 mm spacing, and use factory-formed coils.
Who supplies this helical coil pipe?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, manufactures PA12 and PA11 helical coil tube for oil-air and MQL lines. Send your line layout through our quote page or write to inquiry@isohitech.com.
