Question 1

What sizes does industrial tubing come in?

Accepted Answer

Our standard range covers metric sizes from 4 mm to 16 mm outside diameter (model codes 0425 through 1612) and fractional sizes from 1/8″ to 1/2″, with 3/4″ additionally available in PU and high-pressure composite. Tolerance is ±0.10 mm on both diameters in every family.

Question 2

Is tubing sized by OD or ID?

Accepted Answer

By both, plus the wall between them. A fitting accepts one specific OD-and-wall combination, so two tubes with the same OD but different walls are not interchangeable. The size and wall thickness guide shows how to measure each figure.

Question 3

What does 6/4 mean on a pneumatic tube?

Accepted Answer

It is the outside and the inside diameter in mm: 6 mm OD and 4 mm ID, which gives a wall of 1.0 mm.

Question 4

Does the same OD always mean the same ID?

Accepted Answer

No. Wall thickness determines the inside diameter for a given outside diameter, and a different wall thickness changes both the bore and the pressure rating.

Question 5

How do you accurately calculate tubing wall thickness from outside and inside diameter?

Accepted Answer

Nominal wall thickness is calculated using the formula: W = (OD − ID) ÷ 2. For example, an 8 × 5.5 mm polyurethane tube has a nominal wall thickness of (8.0 − 5.5) ÷ 2 = 1.25 mm. In precision extrusion, wall concentricity should be verified around the full 360-degree circumference.

Question 6

How do I convert inch tubing sizes to millimeters?

Accepted Answer

One inch equals 25.4 mm. Convert the nominal size, then check the actual tolerance from the model table, because the nominal figure is not the exact measurement.

Question 7

What tube goes in a 6 mm push-in fitting?

Accepted Answer

A tube with a 6.0 mm OD, such as the 4.0 × 6.0 mm models (YN-PU 0640, YN-PA6 0640, YN-PA12 0640). A 1/4″ tube has a 6.35 mm OD and belongs in a 1/4″ fitting.

Question 8

Can I use 1/4″ tube in a 6 mm fitting?

Accepted Answer

Use the size the fitting is marked for. The two ODs differ by 0.35 mm, more than the ±0.10 mm tolerance of the model, so they do not swap.

Question 9

How do I know which size to order?

Accepted Answer

Take the fitting specification first: it defines the outside diameter the fitting accepts. Then confirm the inside diameter needed for flow and the wall thickness needed for pressure, using the model table.

Question 10

Can I order a size that is not listed?

Accepted Answer

Custom diameters, walls and coil lengths are confirmed case by case against quantity and application. Send the full requirement through the quotation checklist rather than assuming from the chart.

Question 11

Is PU pipe the same as PU tubing?

Accepted Answer

For compressed-air work, yes: both names describe flexible polyurethane tubing sold on a roll. Data sheets use “tubing” and give the OD and ID, which is the safest way to specify it.

Question 12

What tolerance should I write?

Accepted Answer

Write the tolerance shown in the model row of the table for your model, with its unit. Each row states it, so the specification and the data match.

Question 13

Should I specify Shore hardness?

Accepted Answer

Only if your fitting or application calls for it. Shore A is read on a 0–100 scale under ASTM D2240, and readings on different Shore scales cannot be converted into each other. Hardness alone does not set how flexible a tube is, because wall thickness and construction also matter, so give the bend radius too. Fitting grip is best checked against the fitting maker’s tubing and fitting compatibility chart; for example, the Parker Series U catalog lists 90–95 Shore A for its polyurethane tube and refers to such a chart.

Question 14

What is pneumatic tubing made of?

Accepted Answer

The common families are polyurethane, nylon 6, nylon 12 and polyethylene. Fluoropolymers such as PTFE, FEP and PFA are used where chemical resistance or cleanliness is the deciding requirement.

Question 15

Is nylon stronger than polyurethane tubing?

Accepted Answer

For pressure, generally yes — nylon (PA6/PA12) carries higher working pressures and resists abrasion better, while polyurethane wins on flexibility and flex life. The right pick depends on whether the line moves; the selection checklist compares them point by point.

Question 16

Is PA12 more flexible than PA6?

Accepted Answer

Generally yes. PA12 has the smaller minimum bend radius at 10 of the 14 sizes in our tables; at four metric sizes (8/6, 10/6.5, 10/8 and 12/8) PA6 has the smaller radius. PA6 carries more pressure at nine of the ten metric sizes.

Question 17

Can I replace PA6 tubing with PA12 in the same push-in fittings?

Accepted Answer

Matching nominal OD is the starting point. Check tolerance, wall thickness, hardness, medium, temperature and the fitting manufacturer’s approved tubing specification before changing material. Pressure and minimum bend radius also change between the listed PA6 and PA12 models.

Question 18

Why does PA6 soften when stored in humid warehouses?

Accepted Answer

The supplied PA6 data sheet lists lower tensile properties in the conditioned state than in the dry state. Review the conditioning and operating environment when specifying PA6; use the pressure rating for the chosen model and service conditions.

Question 19

Is polyether tubing the same as polyurethane tubing?

Accepted Answer

Polyether is a grade within the polyurethane family: both are elastic thermoplastics, and the two ranges share the same sizes, tolerances and fitting compatibility. The YN-PUR range is the polyether-TPU grade, specified separately because its pressure ratings and moisture behavior differ.

Question 20

Which grade should I use in a humid environment?

Accepted Answer

Polyether is the default for warm, humid or water-adjacent service; general-purpose polyurethane is the grade that suffers from hydrolysis in those conditions. If the medium itself is aggressive rather than the air, compare the fluoropolymer options instead.

Question 21

Can I use the same tube for air and water?

Accepted Answer

Sometimes, but not automatically. Water changes the pressure and temperature picture, and additives or treatment chemicals may not suit the tube compound. Confirm the medium with the model data.

Question 22

Can PE tubing be used for compressed air?

Accepted Answer

Yes, within the working pressures in the table — 3 to 8 bar depending on size. Confirm that the fittings you use accept PE hardness and tolerance, and leave margin below the table value if the line cycles frequently or runs warm.

Question 23

Does the PE tubing listing establish drinking-water approval?

Accepted Answer

No drinking-water or food-contact approval is established by this product listing. Request the relevant model-specific evidence when your project requires it.

Question 24

Do I need a different tube for a moving axis?

Accepted Answer

Usually yes. Repeated flexing favors a more flexible compound and a longer bend radius, and the cycle count becomes part of the specification rather than an afterthought.

Question 25

How do I specify flame resistant tubing for a pneumatic assembly?

Accepted Answer

Provide the tubing model, dimensions, fittings, operating conditions and the exact fire-test standard or grade required by the project. Request a report identifying the tested product and conditions. The family name and a RoHS chemical report do not establish the required flame-test result.

Question 26

Which sizes of coiled air tubing are available?

Accepted Answer

The tables list metric sizes from 4/2.5 mm to 16/12 mm and inch sizes from 1/8 in to 3/4 in, in PU and in polyether. Check the product page for the exact models.

Question 27

What working pressure does coiled tubing have?

Accepted Answer

Working pressure is a model-specific rating that applies to the complete assembly at a stated temperature. We do not quote a single value. Send your pressure and temperature and we confirm the model.

Question 28

What is FEP tubing and when is it preferred over PFA?

Accepted Answer

FEP is a melt-processable fluoropolymer used for fluid tubing. The YN-FEP sheet lists a finished-product service temperature range of -196°C to +200°C, clear and transparent color options, and size-specific pressure and bend-radius values. Compare these specifications and a sample with the required chemical and optical conditions.

Question 29

What is FEP tubing made of, and what does FEP stand for?

Accepted Answer

FEP stands for fluorinated ethylene propylene, a melt-processable fluoropolymer. The supplied data sheet lists a melting temperature of approx. 260°C and a finished-product service temperature range of -196°C to +200°C. Send your specific medium and operating conditions for review before ordering.

Question 30

What does PFA stand for, and what is PFA tubing?

Accepted Answer

PFA stands for perfluoroalkoxy, a melt-processable fluoropolymer. The supplied data sheet lists a melting temperature of approx. 300-310°C and a finished-product service temperature range of -200°C to +260°C. Send your specific medium and operating conditions for review before ordering.

Question 31

Is FEP tubing the same as Teflon or PTFE tubing?

Accepted Answer

Teflon is a brand name used for several fluoropolymers, including FEP, PFA and PTFE. FEP and PTFE are different materials, so check the material designation and the data sheet rather than the brand name. The FEP product page covers the FEP models listed in its specifications table.

Question 32

Is PFA a type of Teflon?

Accepted Answer

Teflon is a brand name, while PFA is the generic name of the fluoropolymer, and tubing sold under other brand names can also be made from PFA. The PFA product page lists YUANNAI TUBE PFA models; the material grade is stated on the data sheet.

Question 33

Is PFA chemically more resistant than FEP?

Accepted Answer

Use the selected resin grade and chemical compatibility data at the actual concentration, temperature and pressure. Compare the relevant chemical-resistance information and service limits, then confirm the specific tubing against the process requirements.

Question 34

Why does PFA cost more than FEP?

Accepted Answer

Compare quotations for the same size, grade, quantity and documentation. Resin grade, manufacturing process, testing and packaging can change the quotation; specify these requirements together for a meaningful FEP/PFA comparison.

Question 35

Can I see the fluid inside fluoropolymer tubing?

Accepted Answer

FEP tubing is transparent and allows visual flow confirmation. PFA is near-transparent. PTFE is translucent to opaque and does not allow the operator to see the fluid inside.

Question 36

Can FEP and PFA be heat-welded or thermal-formed?

Accepted Answer

Both are melt-processable fluoropolymers. Discuss the required bend shape or formed connection, dimensions, wall and tooling with the supplier, and approve a sample made using the proposed process. The source sheets list different melting temperatures; process settings should follow the actual grade and equipment.

Question 37

Which fittings work best with FEP and PFA tubing (Swagelok / flare fittings)?

Accepted Answer

Choose fittings approved for the exact material, OD, wall, pressure, temperature and medium. For compression or flared connections, follow the fitting manufacturer’s tubing specification and assembly instructions, then review the assembled connection under the intended service conditions.

Question 38

Is burst pressure the same as working pressure?

Accepted Answer

No. Burst pressure is the failure point in testing. Working pressure already includes a safety factor. The two figures must never be compared or substituted.

Question 39

Does working pressure change with temperature?

Accepted Answer

Yes. As temperature rises, the material’s strength decreases and the working pressure must be derated to the value stated at that temperature in the model table.

Question 40

Can I use the 23C rating at 60C?

Accepted Answer

No. Use the rating at the actual operating temperature. If the table does not list that temperature, confirm with the supplier before proceeding.

Question 41

Why do pressure ratings differ at the same size?

Accepted Answer

Material strength and construction differ: the same 8 × 5 size is rated from 7 bar (PU) to 29 bar (PA6) in the tubing size chart. Use the material whose rating covers your working pressure at the actual operating temperature, with margin for cycling.

Question 42

What is the highest working pressure you list for plastic tubing?

Accepted Answer

Among PA6, PA12 and composite tubing, the highest listed working pressure is 41 bar, for YN-PA6 0425 (4 mm OD × 2.5 mm ID) at 23 °C. Every size and its rating is on the product page.

Question 43

Is PA12 or PA6 better for high pressure?

Accepted Answer

At most sizes PA6 is rated higher. PA12 is generally the more flexible of the two, so it is chosen when the line has to bend as well as hold pressure. Compare your exact OD and wall in the tubing size chart.

Question 44

Is composite tubing the high-pressure option?

Accepted Answer

It is the flexible option. Its working pressure sits between 12 and 19 bar across the metric sizes, lower than PA6 at small sizes and close to PA12 at larger ones. Choose it for tight bends and moving machinery.

Question 45

Does a thicker wall increase the pressure rating?

Accepted Answer

Yes. At the same outer diameter, a smaller inner diameter gives a thicker wall and a higher rating. For 8 mm OD PA12 the listed working pressure is 29 bar at 8 × 5 and 17 bar at 8 × 6.

Question 46

Is bend radius measured to the inside or the outside of the curve?

Accepted Answer

Most manufacturers quote it to the centerline of the tube. The convention is not universal, so confirm how the supplied radius is defined before comparing two suppliers.

Question 47

What tubing material is the most chemically resistant?

Accepted Answer

In the published charts we cite, fluoropolymers rate highest: the Professional Plastics chart rates PFA excellent and FEP good in every category it covers. Even they have exceptions, such as molten alkali metals and fluorinating agents, so confirm the specific medium and temperature.

Question 48

Is nylon tubing chemical resistant?

Accepted Answer

Nylon is rated good against oils, greases, alcohols and aromatic hydrocarbons in the Professional Plastics chart, but poor against concentrated acids and halogens. That is why nylon tubing is common on oil and fuel lines and is not chosen for acid service.

Question 49

Is polyurethane tubing chemical resistant?

Accepted Answer

Partly. BASF reports that TPU tolerates lubricating oils and short-time contact with dilute acids and alkalis, but is attacked by concentrated acids and alkalis, swells considerably in aromatic solvents, alcohols and esters, and is dissolved by some polar solvents. Check each fluid, including lubricant additives.

Question 50

Can one tube handle both acids and solvents?

Accepted Answer

Only the fluoropolymer rows in the table are rated for both categories without a weak column. For nylon, polyurethane or polyethylene, acids and solvents usually call for different materials, so list every medium the line will see.

Question 51

Does a chemical resistance chart guarantee a tube will last?

Accepted Answer

No. Charts are general guides for polymer families, with no stated warranty, and resistance depends on exposure time, temperature, concentration, pressure and the exact grade. Treat a chart as a first filter and test a sample under your real conditions.

Question 52

What is the difference between antistatic, static-dissipative and conductive tubing?

Accepted Answer

The ESD Association separates them by resistance: conductive below 1 × 10^4 ohms, static dissipative from 1 × 10^4 up to 1 × 10^11 ohms, and insulative above that. “Antistatic” is a general word, so state the resistance range and test method in your specification.

Question 53

What resistance range do you offer for antistatic PU tubing?

Accepted Answer

It is a custom compound, so the target range is agreed for the project and confirmed on samples. Send the range and the test method you require with your quotation request.

Question 54

Does the SGS RoHS report prove antistatic performance?

Accepted Answer

No. It is a chemical test for restricted substances on one polyether antistatic sample. Antistatic performance needs a resistance measurement by an agreed method.

Question 55

Does static-dissipative tubing need to be grounded?

Accepted Answer

A dissipative material lets charge transfer to ground or to other conductive objects, so charge can only be carried away if there is a path. Plan the connection through the fittings and the rest of the line.

Question 56

Which PU is used for antistatic tubing?

Accepted Answer

Our SGS-tested sample is a polyether antistatic tube. The compound for your project is agreed during technical review against the medium, humidity and temperature of the application.

Question 57

Is multi-lumen tubing the same as multi-core or multi-bore tubing?

Accepted Answer

Yes, in general: all describe tubing with two or more channels in one piece. Suppliers use different names, so describe the number of channels, their sizes and how they are joined.

Question 58

Is multi-lumen tubing the same as a tube bundle?

Accepted Answer

No. A tube bundle carries separate tubes in a shared jacket. Multi-lumen tubing joins the channels along their length. Tell us which one you mean.

Question 59

Can the lines be separated at the ends?

Accepted Answer

It depends on the construction. Single-extrusion multi-bore tubing is generally not separated cleanly, which also affects push-in fittings. State the requirement in your brief and approve a sample.

Question 60

Can each line have a different size or color?

Accepted Answer

Send the requirement. Channels extruded together share one compound, so mixed colors or materials usually call for a different construction, which we review with you.

Question 61

Do you list standard sizes and pressure ratings?

Accepted Answer

No. It is a custom structure, so dimensions and ratings are agreed against your drawing or sample and the operating conditions.

Question 62

What is your minimum order for tubing?

Accepted Answer

500 m per specification for standard products and from 3,000 m per specification for custom products. The final figure is confirmed by material, specification, color, packaging and order quantity.

Question 63

How long is the lead time?

Accepted Answer

5–12 working days for standard products, 8–15 working days for FEP, PFA and composite tubing, and 10–20 working days for custom products. It starts after the technical specification is confirmed and the agreed payment is received.

Question 64

Can I get a sample before a bulk order?

Accepted Answer

Yes. Standard specifications are sampled at 1–3 m. The customer pays the sample fee and shipping, and the fee can be credited against the first bulk order within 6 months. Request a sample.

Tubing FAQ: sizes, materials, pressure and ordering

Sizes and how to specify tubing

Materials and selection

FEP and PFA tubing

Pressure, temperature and bend radius

Chemical resistance

Antistatic PU and multi-lumen tubing

Ordering, samples and pricing

Documents, certificates and testing

Air flow and pressure drop

Related pages