PU Tubing Guide – Ester vs Ether (UV & Water Resistant Options)

🛒 View standard PU tubing (Ester) → [here]

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Compare Ester vs Ether below

Application	Recommended Material
Indoor compressed air	Ester PU
Outdoor use / sunlight	Ether PU
High humidity	Ether PU
Water exposure	Ether PU
Oil / grease environments	Ester PU

When Should You Use Ether PU Tubing?

Ether-based polyurethane tubing should be selected where standard PU may degrade over time, particularly in:

Outdoor installations exposed to UV

Systems with moisture or condensate

Washdown or cleaning environments

High humidity industrial applications

Ether PU provides enhanced hydrolysis resistance, preventing cracking, embrittlement and premature failure.

Polyurethane Airline Tubing – Technical Specification Table

This section includes the most commonly requested metric and imperial sizes, with OD/ID, working pressure, burst pressure, bend radius, roll lengths, and part numbers.

Metric PU Tubing – OD/ID, Pressure Ratings & Part Numbers

OD (mm)	ID (mm)	Working Pressure	Burst Pressure	Min Bend Radius (mm)	Roll Length (m)	Part Number
4	2	22 bar / 312 psi	66 bar	15	200	PU-0420 + colour
4	2.5	15 bar / 217 psi	45 bar	15	100	PU-0420-100M + colour
4	2.5	15 bar / 217 psi	45 bar	15	200	PU-0425 + colour
6	4	14 bar / 203 psi	42 bar	25	100	PU-0640-100M + colour
6	4	14 bar / 203 psi	42 bar	25	200	PU-0640 + colour
8	5	15 bar / 217 psi	45 bar	30	100	PU-0850 + colour
10	6.5	14 bar / 203 psi	42 bar	40	100	PU-1065 + colour
11	8	6 bar / 85 psi	18 bar	35	100	PU-1180 + colour
12	8	13 bar / 188 psi	39 bar	50	100	PU-1280 + colour
16	12	9 bar / 130 psi	27 bar	100	50	PU-1612 + colour
16	13	5 bar / 70 psi	18 bar	100	50	PU-1613 + colour

Colour Options

Standard colours: Blue (BL), Black (B), Orange (OR)

Optional colours:

Red (R), Yellow (Y), Transparent (T), Green (G), White (W)

Buy Polyurethane tubing online.

Physical Properties – Tested to ASTM Standards

Property	Value	Standard
Hardness (Shore A)	98A	ASTM D-2240
Tensile Strength	600 bar	ASTM D-638
Ultimate Elongation	490–590%	ASTM D-638
Taber Abrasion	30–40 mg	ASTM D-1044
Tear Strength	155 bar	ASTM D-732

These results confirm the tubing’s suitability for high-cycle pneumatic applications.

QC Summary Report – Polyurethane (PU) Tubing Material

Material: Polyurethane Pellets (Grade EB-98A3)

Batch No.: 10118923

Shipment Date: 05 November 2025

Order No.: 25001251-SO

Download the test report

1. Test Results Overview

Hardness (Shore A – ASTM D2240)

Specified Range: 96 – 99

Result: 98

Status: Pass

Melt Index MI (8.7 kg / 205°C) – ASTM D1238

Specified Range: 30.00 – 50.00 g/10 min

Result: 37.23 g/10 min

Status: Pass

Moisture Content (IR Balance – Coating P. Method)

Specified Range: 0.00 – 0.30%

Result: 0.18%

Status: Pass

2. Summary

All measured parameters fall within the supplier’s controlled limits.
The polyurethane material meets the required QC criteria and is classified as Qualified / Acceptable for Use.
This batch is suitable for extrusion of high-performance PU pneumatic tubing.

3. Additional Notes

Material grade EB-98A3 is consistent with previous Shako/TPU supply batches.

No deviations, defects, or anomalies were recorded during testing.

QC documentation includes the original supplier inspection report and authorised signatures.

The material’s melt index, hardness, and moisture levels confirm stable processing behaviour for tubing extrusion.

QC Summary – PU Pellet Material (Batch EB-98A3)

All QC parameters (Shore hardness, MI, moisture content) fall within the supplier's controlled limits. This confirms the material is suitable for extrusion of PU pneumatic tubing.

Polyester vs Polyether Polyurethane (PU) – Full Material Science Comparison

Polyurethane airline tubing is manufactured using two primary material families: polyester-based PU and polyether based PU. Each type has distinct mechanical, chemical, and environmental characteristics that make it more suitable for certain applications.

This expanded comparison clarifies the technical differences to help engineers, OEMs, and pneumatic system designers choose the right formulation for their environment.

Polyester-Based Polyurethane (Standard Grade)

Polyester PU is the industry standard for general-purpose pneumatic airline tube.

Key Characteristics

Outstanding abrasion resistance
Ideal for high-cycle pneumatic systems where tubing regularly rubs against machine frames, tools, or cable tracks.

Excellent oil and fuel resistance
Performs well in environments exposed to lubricated air, hydrocarbons, compressors, and machining oils.

High tensile strength & mechanical rigidity
Offers precise dimensional stability, making it ideal for tight tolerances in push-in fittings.

Cost-effective
Typically around 10–30% cheaper than polyether formulations.

Limitations

Not recommended for high-humidity, wet, or water-contact environments
Polyester PU can hydrolyse over time, leading to:
Volume swell Reduction in mechanical strength Tube softening Hazy or cloudy appearance

Reduced hydrolytic stability
Long-term exposure to water or moisture accelerates degradation.

Typical Shelf Life

Approx. 3 years (assuming indoor dry storage)

Best suited for

Indoor pneumatic machinery

Dry factory environments

Robotics and pick-and-place systems

Air tools and automation

OEM machine-building using push-fit fittings

This is the default material for Shako’s standard PU airline tubing.

Polyether-Based Polyurethane (Premium Upgrade)

Polyether-based PU is the premium airline tubing choice, designed for harsh environments with moisture, water spray, condensation, outdoor conditions, or fluctuating temperatures.

Key Characteristics

Superior hydrolysis resistance
Unlike polyester PU, polyether PU does not readily break down in the presence of water.
It remains stable in water up to 50°C, even for extended periods.

Excellent low-temperature flexibility
Maintains elasticity and bend radius in cold environments where polyester PU can stiffen.

Fungus and microbial resistance
Critical for food processing, agriculture, HVAC, and damp industrial facilities.

High UV resistance
Ideal for tubing exposed to direct sunlight, outdoor installations, and solar heating effects.

Longer working life
Typically 5+ years, making it almost double the longevity of polyester PU.

Limitations

Higher cost
Generally 20–40% more expensive than polyester versions.

Water temperature limits
Although durable in ambient or warm water, it is not recommended for running water over 70°C.

Best suited for

Outdoor pneumatic systems

High-humidity environments

Water spray areas, washdown zones, and coolant exposure

Food and beverage equipment

Marine/aquaculture automation

Cold rooms and refrigerated production

Polyether PU is not the standard Shako supply, but it is available as an optional upgrade from the manufacturer.

Side-by-Side Technical Comparison

Property	Polyester PU (Standard)	Polyether PU (Optional Upgrade)
Abrasion Resistance	★★★★★ Excellent	★★★★☆ Very Good
Oil Resistance	★★★★★ Excellent	★★★☆☆ Moderate
Hydrolysis / Water Resistance	★★☆☆☆ Poor	★★★★★ Excellent
UV Resistance	★★★☆☆ Good	★★★★★ Excellent
Low Temperature Flexibility	★★★☆☆ Good	★★★★★ Excellent
Tensile Strength	★★★★★ High	★★★★☆ High
Shelf Life	~3 years	5+ years
Cost	Lower	Higher
Outdoor Suitability	Limited	Excellent
Best For	General Pneumatics	Wet / Outdoor / Cold Environments

Practical Engineering Summary

Choose Polyester PU tube if:

✔ You need a tough, abrasion-resistant tube
✔ The installation environment is dry
✔ Cost efficiency is important
✔ The system uses lubricated air
✔ You require excellent rigidity for push-in fittings

Choose Polyether PU tube if:

✔ The tubing is exposed to water spray or condensation
✔ The environment is outdoor or UV-exposed
✔ The application involves refrigeration or low temperatures
✔ Hygiene, mould resistance, or hydrolysis stability is critical
✔ Maximum tubing lifespan is a priority

Final Recommendation

For standard indoor pneumatic systems, polyester PU offers the best balance of price and performance.

For humid, outdoor, cold, or wet environments, upgrading to polyether PU dramatically improves service life and reliability.

PU vs Rubber Elastomers – Comparative Performance Chart

PU demonstrates excellent performance in:

Tensile strength

Elongation

Resilience

Tear strength

Abrasion resistance

Impact resistance

Compared against: NBR, EPDM, SBR, FPM, CR, IIR, NR, SIL.

PU ranks among the top for durability and dynamic mechanical performance.

Frequently Asked Technical Questions

What is Shore Hardness (Shore A – ASTM D2240)?

Shore Hardness is a standardised measurement of how resistant a material is to indentation. For elastomers like polyurethane (PU), this is measured using the Shore A scale, defined under the international test method ASTM D2240.

How the test works

A Shore A durometer uses a spring-loaded indenter that presses into the surface of the material with a controlled force.
The depth of the indentation is translated into a number on the Shore A scale:

0 Shore A → very soft, gel-like materials

40–60 Shore A → flexible rubbers (e.g., soft silicone)

90–98 Shore A → tough elastomers like high-performance PU

100 Shore A → extremely hard elastomers, almost rigid

Why PU Tubing is Typically Shore 95–98A

This hardness level provides:

High abrasion and wear resistance

Excellent dimensional stability under pressure

Low permanent deformation (low compression set)

Tight bend radius without collapsing

Long life under repeated flexing

This makes 98A PU ideal for:

Pneumatic airline systems

Push-in fittings (no cutting or leakage from deformation)

Robotic applications with constant movement

Industrial environments with mechanical abrasion

Why this matters in real-world pneumatic systems

The correct hardness ensures:

The tube stays round inside a push-fit fitting

The wall doesn’t collapse during tight bends

The tube resists scratching, gouging and wear

The internal bore stays smooth for optimal airflow

It maintains performance across temperature changes

A softer tube (70–80A) would kink more easily and perform poorly under pressure. A harder tube (100A) would lose flexibility, making installation difficult.

What is Melt Index MI (8.7 kg / 205°C)?

The Melt Index (MI) — also called Melt Flow Index (MFI) — is a standard measure of how easily a plastic melts and flows when heated. For polyurethane pellets used in PU tubing, this property is critical because it directly affects extrusion quality, surface finish, dimensional accuracy, and mechanical performance.

The test method is defined by ASTM D1238, the global standard for measuring the flow rate of thermoplastics.

How the Melt Index Test Works

During the MI test:

The material is heated to a standard temperature of 205°C.

A weight — in this case 8.7 kg — is placed on a piston above the molten polymer.

The molten polymer is forced through a precision die.

The amount of material that flows out over 10 minutes is weighed.

The result is expressed as:

Grams of polymer per 10 minutes (g/10 min)

What Melt Index Numbers Mean

A higher MI means the molten polyurethane flows more easily (lower viscosity).

A lower MI means the material is thicker when molten (higher viscosity).

The acceptable range for your PU tubing material is:

30.00 – 50.00 g/10 min

This tells us:

The material flows smoothly during extrusion

The surface finish of the tubing will be uniform

OD/ID tolerances will remain consistent

There is no excessive shear or degradation during extrusion

What is Polyurethane Moisture Content (IR Balance)?

Moisture Content refers to the amount of water absorbed into the polyurethane (PU) pellets before extrusion. Even small amounts of moisture can significantly affect clarity, mechanical strength, surface finish, and dimensional stability of PU airline tubing.

The Shako QC report, the moisture content was measured using the IR Balance Method, also known as Infrared Moisture Analysis — a precise and rapid technique used in polymer quality control.

(The batch measured 0.18%, well within the specification of 0.00–0.30%, see test report here.)

Applications of PU Airline Tubing

Pneumatic control systems

Solenoid valve actuation lines

Automation and robotics

Packaging machinery

High-speed pick-and-place

Air tools

Automotive air systems

Industrial production lines

Why Choose Connexion PU Tubing?

Manufactured using premium pellets

Consistent quality backed by ASTM standard testing

Wide colour and size range

Fast UK delivery with large stock holdings

Full technical support & material documentation

Compatible with all push-in and pneumatic fittings

Request Ether PU Tubing

We supply Ether-based PU tubing in all standard sizes and coil lengths.

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• Pricing
• Lead times
• Technical selection advice

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