Danish
Updated: 13 October 2026
Published: 30 September 2019
Guide to choosing pneumatic fittings
Six questions that help you choose the right fitting for your compressed air or low-pressure application
You find the right pneumatic fitting by looking at six factors: the application environment, the medium to be transported, the pressure and temperature requirements, the other components in the system, applicable regulations and the supplier's quality. The material, the seal and the retaining technique must match all six — otherwise you risk leakage, wear and downtime.
What is a pneumatic fitting?
Definition: A pneumatic fitting is a connector that joins tubes, hoses and components in a compressed air system or another low-pressure system. Fittings are also used for vacuum, water and other liquids. The range has grown considerably as low-pressure applications have become more widespread, which can make it difficult to find the fitting that best suits your needs. This guide helps you make the right choice.
Which materials are pneumatic fittings available in?
Choice of material: For many years, brass and stainless steel were the standard materials. New surface treatment techniques and alloys have improved their performance, and ranges of engineering polymer fittings have been added, making the selection even wider.
| Material | Properties | Typical application |
|---|---|---|
| Brass (often nickel-plated) | Robust and cost-effective | General industry and machine building |
| Stainless steel 303 | Good corrosion resistance | Damp environments and mildly aggressive media |
| Stainless steel 316L | High corrosion resistance | Food, pharmaceutical and marine environments |
| Engineering polymers | Lightweight and corrosion-free | Automation, food, pharmaceutical, packaging and compact machinery |
Which seal should the fitting have?
Seal material: Seal materials are developed to handle different gases and liquids, e.g. air, water, oil and grease. The seal must always be compatible with both the medium and the operating environment — otherwise the system cannot be kept tight. Typical seal materials are NBR (nitrile) for compressed air and mineral oil, and FKM for higher temperatures and more aggressive media.
How is the tube retained in the fitting?
Retention: The connection to the tube is crucial for keeping the system tight. Today there are four main techniques:
- Collet: The tube is pushed into a push-in fitting and held by a collet. It is released by pressing the release ring.
- Gripper ring: A toothed gripper ring in the push-in fitting holds the tube in place. Also released by pressing the release ring.
- Barbs: The tube or hose is pressed onto a barbed stem.
- Compression: A nut clamps a ring around the tube. The technique is used in universal fittings, among others.
Each technique has advantages and limitations depending on the application. Push-in fittings are quick to fit and remove, while barbed and compression fittings are often chosen where the connection rarely needs to be disconnected. At Hymatik you will find push-in fittings from Parker Legris, among others.
Which six factors should you consider?
Everyone has their own preferences and experience, but there are some universal rules you should always follow to avoid basic mistakes.
1. What is the application environment like?
Environment: Look at the air quality (dry, salty or dusty), the temperature, chemical contact (e.g. cleaning agents), vibrations and particles such as sparks or chips. If you work in potentially explosive areas, the equipment must comply with the ATEX Directive (2014/34/EU). Fittings without their own ignition source are often exempt, so always ask for the manufacturer's declaration of conformity.
2. Which gases and liquids are to be transported?
Medium: Know the exact properties of the medium so you can choose a material and seal that are compatible with it. This applies to compressed air, vacuum, water and oil alike.
3. What are the requirements for pressure, temperature and flow?
Performance: Determine the requirements for working pressure, temperature, flow and vibration, and compare them with the fitting's data in the data sheet. Check the permissible pressure at your operating temperature, as plastic tubing typically withstands less pressure at high temperatures.
4. What other components are in the system?
System: Fittings are a small part of a circuit with tubing, valves and couplings. All components must meet the same requirements. The tubing material (e.g. polyamide or polyurethane) and outside diameter must match the fitting, and the thread must match the port on the cylinder or valve.
5. Are there regulations and market requirements you need to meet?
Regulations: In some industries, e.g. food and pharmaceuticals, you must meet legal and operational requirements. These may be requirements for materials approved for food contact under EU Regulation 1935/2004 or FDA. Requirements like these are non-negotiable.
6. What is the manufacturer's quality and service like?
Supplier: Consider who the supplier is, and whether the supplier is also the manufacturer. This affects delivery time, support when problems arise and access to spare parts, both nationally and internationally. Also ask whether the manufacturer works to quality systems such as ISO 9001 or IATF 16949, which has replaced ISO/TS 16949 in the automotive industry.
Which thread should the fitting have?
Thread: The fitting's thread must match the port in the component. The most common types are BSPP (parallel), BSPT (tapered), NPT and metric threads. If you are in doubt, you can use our thread identification chart to identify the thread type and sealing form.
Checklist: How to choose pneumatic fittings
| Factor | What you need to determine |
|---|---|
| Environment | Air quality, temperature, chemicals, vibrations and particles |
| Medium | Which gas or liquid, and are the material and seal compatible? |
| Performance | Working pressure, temperature and flow |
| System | Tubing material, tubing diameter, thread and other components |
| Regulations | E.g. food approval or ATEX |
| Supplier | Delivery time, spare parts and quality systems |
Frequently asked questions (FAQ)
What is the difference between a push-in fitting and a compression fitting? A push-in fitting holds the tube with a collet or gripping ring, so the tube is simply pushed in. A compression fitting clamps a ring around the tube with a nut.
When should I choose stainless steel fittings? When the environment calls for high corrosion resistance, e.g. in the food and pharmaceutical industries or in marine environments. Stainless steel 316L is typically used here.
Can pneumatic fittings be used for vacuum and water? Many can, but always check the data sheet and make sure the seal is compatible with the medium.
How do I find the right thread? Use our thread identification chart to identify the thread type and sealing form.
See our range of pneumatic fittings
Do you have questions about choosing pneumatic fittings? Call +45 63 12 83 00 or write to ps@hymatik.com. Our pneumatics specialists are happy to help.
