A plastic distribution system based on PA12 and push-fit fittings is suitable for workshops and light to medium-duty industry up to the working pressure typical for these systems. The conditions are correct sizing of diameters according to air consumption, quality filtration and drying, and installation according to the manufacturer's instructions. For heavier operations with high demands on mechanical resistance, an aluminium system remains the better choice. If you are not sure what type of distribution system your operations need, the technical support of Kompresory-vzduchotechnika will verify the design before purchase.
In short:
- Plastic PA12 distribution systems with push-fit joints can handle working pressure up to 16 bar, but are less resistant to mechanical damage and aggressive environments.
- Aluminium systems are more suitable for demanding operations with higher requirements on mechanical resistance and long-term stability of parameters.
- When sizing the distribution system, it is key to calculate the actual air consumption and add a reserve for future expansion instead of precisely planning the diameter.
- Installation of plastic pipes requires precision, correct deburring, insertion into the fitting, and secure fastening, while a pressure test reveals any leaks.
- A combination of an aluminium backbone with plastic branches is the most effective solution for balancing performance, durability, and costs in workshops and medium-sized operations.
Contents
- Plastic or aluminium: how to choose the material for air distribution
- Components and fittings: what a complete plastic distribution system includes
- How to size a plastic distribution system: procedure and calculation examples
- How the installation of a plastic distribution system proceeds step by step
- Connection to the compressor: air filtration and drying
- Maintenance of the air distribution system: what to check and how to fix faults
- Expert recommendation from Kompresory-vzduchotechnika for distribution system design
- Why conventional advice on sizing often fails
- Design and installation of the distribution system with Kompresory-vzduchotechnika
- Frequently asked questions
Plastic or aluminium: how to choose the material for the air distribution system
The choice between a plastic and an aluminium compressed air distribution system is not governed by price, but by operating conditions: pressure, temperature, mechanical load, and the environment through which the piping will run.
Plastic pipes made of PA12 can handle working pressures within the usual range used for these products and working temperatures within the range specified by manufacturers in technical datasheets, typically from light frost up to +60 °C. They are lightweight, do not corrode, and are installed without soldering or thread cutting. The push-fit system works on the principle of a plug-in connection with an O-ring; the pipe is simply pushed into the fitting and the joint is ready within seconds. It is precisely this speed of installation without special tools that reduces labour costs and the time needed for installation, which is especially noticeable in larger distribution systems with dozens of branches.
However, the limitations of plastic become apparent elsewhere. Push-fit joints have lower mechanical resistance to impacts and vibrations than welded or pressed aluminium joints, and in more aggressive chemical environments (solvents, certain oils) the pipe material or seals may degrade. For this reason, plastic is not suitable for facilities with intensive machine traffic, where mechanical damage to the piping is a risk, nor for environments with a high concentration of aggressive vapours.
Aluminium systems, such as the modular AIRnet solution designed according to the EN 13480-3 standard, can handle working pressure corresponding to common standards for this type of system, and thanks to their smooth internal surface, they have low pressure losses even over long runs. They are necessary where the distribution system must handle higher flow rates, where mechanical damage is a risk, or where operation requires long-term stable parameters without the risk of the plastic ageing.
In practice, a combination of both materials often proves effective. The backbone line, i.e. the main run from the compressor to the distribution points, is handled in aluminium for maximum durability and low pressure losses. The individual branches to the work stations are then completed with a plastic air distribution system, which is faster and cheaper to install.
Decision criteria for material selection:
- Working pressure and its stability – is the operation approaching the 16 bar limit, or is there a reserve?
- Mechanical risk – is a forklift operating in the area, can tools fall onto the piping, is there a risk of impact?
- Chemical environment – are there solvents, oils, or aggressive vapors in the air?
- Length and scope of the distribution system – is it a small workshop, or a large hall with dozens of outlet points?
- Budget and installation time – is there time available for a more complex installation, or is the priority a quick commissioning?
The combination of an aluminum backbone plus plastic branches is in practice the most efficient compromise between performance and cost, because it concentrates the investment in durability where it is actually needed, and saves money in places with lower risk.
Components and couplings: what a complete plastic distribution system includes
A complete plastic compressed air distribution system consists of more than just pipes. It functions as a system of several types of components, which must match each other in terms of pressure and material.
- PA12 pipes – form the backbone as well as the branches of the distribution system. Typical diameters for smaller workshops range from 15 to 28 millimeters for branch lines and around 32 millimeters for the main line. In larger facilities with higher consumption, pipes of 32 to 63 millimeters are used.
- Push-fit fittings – elbows, T-pieces, reducers, and couplings that allow assembly without tools. Quality fittings have integrated O-rings resistant to the oil contained in the compressed air system.
- Distribution boxes – local collection points from which air is distributed to individual workstations. They increase workplace flexibility, as they allow additional expansion with another outlet point without intervening in the main line.
- Shutoff valves and quick couplings – ball valves for isolating individual branches during servicing, and quick couplings for connecting pneumatic tools or hoses.
- Condensate separators and condensate drains – located at the lowest points of the distribution system, where moisture condenses, and at the inlets to distribution boxes.
- Pressure gauges – mounted at key points of the distribution system, usually at the outlet from the compressor station and at more distant end points, to allow monitoring of pressure drop.
- Mounting accessories – clamps, brackets and fasteners for securing the piping to the wall or ceiling according to the manufacturer's recommended spacing.
At critical points, such as transitions to the compressor, main shutoff valves or pneumatic tool connections, brass or steel fittings are often chosen instead of plastic ones. These materials better withstand repeated screwing, vibration from the compressor and mechanical stress when connecting hoses. The combination of "plastic on the run, metal at the contact points" is a common approach that extends the service life of the entire compressed air distribution system in the workshop without unnecessary extra cost.
How to size a plastic distribution system: procedure and calculation examples
Sizing a compressed air distribution system follows simple logic: first you determine how much air the system actually needs, then you select a diameter that will carry this consumption with an acceptable pressure drop, and finally you verify the design at the most distant end point.
Step 1: Determining the total flow rate. You add up the consumption of all pneumatic tools and machines that may be operating simultaneously, not the theoretical consumption of all equipment at once. In a workshop with multiple guns, it is common to assume that not all of them run continuously, so a simultaneity factor is used (usually 0.5 to 0.7 depending on the type of operation).
Step 2: Selecting the main line diameter. According to manufacturers' catalogue tables, for a given combination of flow rate and line length, the minimum diameter is selected that ensures a pressure drop within the recommended limit.
Step 3: Calculating pressure losses. Pressure loss increases with pipe length, the number of bends and fittings, and decreases with a larger diameter. A practical rule for workshop and smaller industrial distribution systems is to keep the total loss on the main line below 0.3 bar between the compressor station and the most distant take-off point.
Step 4: Verification at the end point. The most distant or highest-positioned workstation is the most critical point of the entire system. If the pressure drops there below the value required for correct tool operation, the entire design must be recalculated with a larger diameter or a shorter run.
Example calculation: a small workshop with three guns
The workshop uses three pneumatic blow guns, each with a consumption of around 250 litres per minute at peak load. With a simultaneity factor of 0.6, the actual peak consumption comes to approximately 450 litres per minute. For this consumption and a run of up to 20 metres, a 32 mm diameter backbone pipe with 15 to 20 mm branches to individual stations is usually sufficient.
Sample calculation: small production workstation with five outlets
An operation with five outlet points (a combination of blow guns and smaller pneumatic tools) and a total peak consumption of around 900 litres per minute over a run exceeding 40 metres already requires a 40 to 50 mm backbone to keep pressure loss within an acceptable range. Here it is worth considering an aluminium backbone with plastic branches.
Practical recommendations for forward-looking design:
- Design the backbone diameter with a reserve of one to two sizes above the current requirement, rather than sizing it exactly to the current consumption.
- Position distribution boxes so that they allow additional outlets to be connected without intervening in the main line.
- Keep in mind that every future branch will increase the pressure loss on the backbone, so a reserve in diameter pays off financially as well, since it avoids a complete rebuild of the distribution system.
- For operations anticipating production expansion, it is better to invest in a backbone one size stronger right at the first installation.
A detailed procedure with specific pressure loss tables and recommended diameters for various scenarios can be found in a separate guide to sizing compressed air distribution systems.
How the installation of plastic piping proceeds step by step
Installing compressed air with plastic piping is faster than with welded systems, but the precision of individual steps determines how long the distribution system will last without leaks.
- Route preparation. Check the strength of the walls or ceiling for mounting, calculate the minimum bend radii according to the pipe manufacturer's specification, and plan the spacing of brackets, usually every 50 to 100 centimetres depending on the diameter.
- Cutting and deburring. Cut the pipe at a right angle using special pliers or a saw designed for plastic, then remove burrs from both the inner and outer edges. Burrs are the most common cause of O-ring damage when inserting into the fitting.
- Cleaning the pipe end. Before inserting into the fitting, wipe the pipe end with a dry cloth to prevent shavings or dust from entering the joint.
- Insertion into the push-in fitting. Insert the pipe with even pressure all the way to the stop, not at an angle. Most push-fit systems have a visual mark on the pipe or fitting that confirms the correct insertion depth.
- Joint inspection. After insertion, try gently pulling the pipe back. A properly made joint will lock and not loosen. If a joint is questionable, disassemble it and redo it.
- Pipe fixing. Secure the line using clamps and brackets at the recommended spacing so that the piping does not transfer its own weight onto the joints.
- Pressure test. Before commissioning, the distribution system is tested at a pressure of 1.5 times the rated working pressure for 30 to 60 minutes. Monitor the pressure drop on the pressure gauge and check all joints using a foam test solution.
Professional tip: A leak in a push-fit joint is most often detected by a hissing sound when the compressor is switched off and the workshop is quiet. If the pressure keeps dropping during the test even after a visual check of all joints, focus on the points where the pipe changes direction — insertion is most often imperfect there.
The most common installation error is insufficient insertion of the pipe into the fitting, whether due to burrs or failure to align with the depth mark. The second typical error is overtensioning the pipe between brackets, which leads to mechanical stress on the joints during temperature changes. A detailed installation checklist can be found in the guide to setting up a compressed air distribution system step by step.
Connecting to the compressor: air filtration and drying
A plastic compressed air distribution system is more sensitive to the quality of the air passing through it than an aluminum system, because moisture and contaminants damage the seals in push-in fittings more quickly. Filtration and drying are therefore not an add-on, but a condition for long service life.
Quality air treatment prevents the accumulation of condensate and mechanical contaminants, which otherwise shorten the service life of plastic pipes and joints. Moist air also promotes corrosion of metal fittings in the system and increases the risk of condensate freezing during winter months in unheated workshops.
For workshop operation, a combination of a cyclone separator and a membrane or adsorption dryer with an achieved dew point of around +3 to +5 °C is usually sufficient. Industrial operations with higher demands on air dryness, such as paint shops or food industry lines, choose adsorption dryers with a lower dew point and multi-stage filtration.
Recommended placement of air treatment components in the distribution system:
- Main filter and dryer right after the compressor's air receiver, before the split into the backbone line.
- Secondary filters at distribution boxes leading to sensitive applications (spray guns, measuring instruments).
- Condensate drains at every lowest point of the line and at the entry to vertical branches.
- Pressure safety margin between the maximum working pressure of the plastic piping (up to 16 bar) and the set pressure of the compressor; a margin of at least 1 to 2 bar is recommended.
The basic principles of how the whole system works, including the role of the compressor and air treatment, are described in the article on how pneumatics works in industry.
Maintenance of the air distribution system: what to check and how to fix faults
Regular inspection of the compressed air distribution system reveals minor leaks before they manifest as a loss of compressor performance or unnecessary energy costs.
Monthly, it is advisable to check noisier joints by listening and to visually inspect the visible piping routes. Annually, a more thorough inspection is recommended, including a pressure test of the entire system and a check of the condition of the filters and dryer.
- Leak diagnostics – an ultrasonic leak detector or a simple foam spray will reveal even small leaks that are inaudible during normal listening checks.
- Pressure drop measurement – a portable pressure gauge placed at the beginning and end of the line will show whether the losses are increasing compared to the designed values.
- Most common faults – a loose push-fit connection (solution: disassemble, check the O-ring, reinsert), an O-ring damaged by aging (replace with an original part), a clogged condensate drain (cleaning or replacement).
- When to call service – in case of repeated leaks at the same spot, pressure drop even after checking the connections, or during a planned inspection of the entire compressed air system including the compressor station.
A service intervention should include not only repairing the specific fault, but also checking whether a systemic problem has occurred, such as a poorly dimensioned line or inadequate air treatment.
Expert recommendation from Kompresory-vzduchotechnika for distribution design
A typical inquiry that smaller workshops bring to Kompresory-vzduchotechnika concerns distribution for three to five work stations with a combination of blow guns and manual pneumatic tools. For production facilities, it is often about expanding an existing distribution system to add a new line or workstation.
Before consulting a technician, it makes sense to have basic data ready: the expected number of stations and their current air consumption, the required working pressure at the end tools, and an estimate of the line length from the compressor. With these details, the diameter design and material choice can be verified during a single consultation, instead of fixing mistakes after installation.
Zdeněk, who handles technical consulting on compressed air systems at Kompresory-vzduchotechnika, has long observed that the most common cause of dissatisfaction with a plastic distribution system is not the material itself, but an undersized backbone diameter already at the design stage.
Why conventional dimensioning advice often fails
Most guides to compressed air distribution focus on which material is "better," while underestimating that ninety percent of real-world problems arise from poor dimensioning, not the choice of plastic or aluminum. I have seen facilities where a plastic push-fit distribution system has worked without a single failure for ten years, because it was designed with a margin. And I have seen aluminum installations where investing in a more expensive material did not save an undersized backbone.
Conventional advice also often overlooks that filtration and drying are not a cosmetic add-on, but directly affect how long push-in connections last. Condensate in the piping ages O-rings faster than UV radiation or temperature fluctuations.
If I had to recommend a single priority to readers, it would be this: before deciding on the material, calculate the actual consumption with a simultaneity factor and add a margin for future expansion. The material is the second decision, not the first.
— Zdeněk
Design and installation of distribution systems with Kompresory-vzduchotechnika
Kompresory-vzduchotechnika handles compressed air distribution comprehensively, from diameter calculations through component supply to installation and service, so you don't have to rely on estimates or combine deliveries from multiple vendors. We offer a turnkey design including technical consultation, supply of both plastic and aluminum components, an installation team, and service support for any later modifications or inspections.
Proper air treatment is also part of every functional distribution system. Our range includes compressed air treatment units for removing impurities, as well as dryers for condensate removal, which extend the lifespan of the entire distribution system. For operations with higher working pressure, robust treatment units up to 18 bar are also available.
If you're not sure what pipe diameter and what type of air treatment your workshop or facility needs, ask the Kompresory-vzduchotechnika technical support team for a design proposal or price quote before ordering materials.
Frequently Asked Questions
Up to what pressure is a plastic compressed air distribution system safe?
Plastic systems made of PA12 material with push-in fittings can handle a working pressure of up to approximately 16 bar, though the exact value varies depending on the manufacturer and fitting type, so always check the technical data sheet of the specific product.
What pipe diameter should be chosen for a small workshop?
For smaller workshops with a few blow guns, pipes of 15 to 28 millimeters for branch lines and 32 millimeters for the main line are usually sufficient, but the exact diameter depends on the number of outlets and the length of the route.
How long does a plastic distribution system last compared to an aluminum one?
With proper installation, filtration, and air drying, a plastic distribution system will last for many years without issues, but aluminum systems generally withstand mechanical loads and harsher environments better, making them more durable in demanding industrial settings.
How is leak tightness tested after installation?
The distribution system is tested at 1.5 times the nominal working pressure for 30 to 60 minutes, during which the drop is monitored on the pressure gauge and the joints are checked using a foam test solution.
When is it better to combine plastic with aluminium?
The combination pays off where the main backbone line needs higher mechanical resistance and low pressure losses, while individual branches to workstations can be solved more quickly and cheaply with a plastic distribution system. Kompresory-vzduchotechnika recommends this modular approach as a common standard for medium-sized operations.