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Frequently asked questions

In our FAQs we answer frequently asked questions about our products and the online shop. If the answer to your question is not there, please feel free to contact us.

Onlineshop

    • When do I have to enter a VAT ID number?

      If you are a customer from another EU country, please enter your VAT ID number when registering. This will prevent you from being charged German sales tax. Deliveries to other EU countries will take place tax-free if the VAT ID number is correct. Non-EU customers may not enter any other tax number in the VAT ID field as this will result in an error during registration. These include, for example, Great Britain, USA, Canada, Switzerland,... Customers from Germany are always charged German sales tax. Entering your VAT number is therefore optional and does not change anything.

    • Why does my registration with VAT Id fail?

      Our shop tells you what the problem is. Maybe the name of your company is not exactly written as in the VAT register or format of the number is not correct. You can easily check the correct writing of your company as it is in the VAT register on this website: https://www.experte.de/ust-id-pruefen
      If you get: "An error occurred while processing the data for the requested EU member state, and your request could not be processed." the validation instance is technically not reachable at the moment. This is a problem you cannot resolve yourself. The only possibility is to try again later or tomorrow.

    • We are a university/college/school/authority and can only purchase on account. Is that possible for you?

      Yes, if our system recognizes that you belong to this group based on the contact details you have entered, you will automatically be given this payment method to choose from. If the purchase on invoice is not displayed, please send us an email to shop@maku-industrie.de with your contact details and we will manually give your user account authorization to purchase on account.

    • To which countries does the delivery take place?

      Customers from various European countries as well as North America and some other countries can order directly in the online shop. A current, complete list can be found here: Shipping information

    • How long is the delivery time?

      In Germany, delivery is usually via UPS within 1-2 working days. This time for the transport of goods is already included in our delivery time information for the items. For further information and other countries please check Shipping information.

    • Why can't I order by express even though the products are in stock?

      Normally, this problem occurs when "Prepayment" is set as the payment method. Change the payment method to a method where payment is made immediately upon completion of the order, such as PayPal, credit card, Amazon Pay,... After that, an express shipping option should also be available.

Quick couplings

    • Is it called quick coupling or quick-release coupling?

      Both terms can be used and mean exactly the same thing. We use the quicker, shorter term: quick coupling.

    • What is the universal standard compressed air coupling on the compressor?

      This is typically a 7.2 bore series 26 brass standard air coupling. Depending on the required sealing material and connection thread or connection hose, several products can be used: Pneumatic standard

    • What does single or double shut-off mean?

      In the case of connection systems that shut off on one side, a valve is installed only in the quick coupling, which prevents the medium from escaping after the connection has been separated. In the case of double shut-off connections, the plug also contains a valve that prevents leakage. Caution: Quick coupling and plug must be matched to each other. A double shut-off quick coupling (item number with KB) also requires a plug (item number with SB) that is capable of doing so.

    • Can I mix and match a shut-off quick coupling and a straight-through plug?

      If the quick coupling is a single shut-off variant, it is possible to couple it with a plug with a free passage. However, a plug designed for shut-off on both sides also requires a double-shut-off quick coupling in order to be able to be coupled.

    • How do I find the right plug for my quick coupling?

      For quick couplings and plugs, you will find a list of all fitting counterparts further down the page.

    • Which seal in the quick coupling do I need for hydraulic oil/steam/petrol?

      Depending on the medium, a different sealing material is required in the quick coupling. Eventually, the media will attack the seal, causing it to swell or become brittle, allowing the connection to leak over time. A list of which sealing material is suitable for which medium can be found here: Resistance table O-rings

    • What does "two-hand operation" mean?

      With two-hand operation, the quick coupling and plug can only be connected if the sleeve on the quick coupling is pulled during the coupling process.

    • When do I need a pressure eliminator?

      The pressure eliminator enables problem-free coupling even under dynamic or residual pressure. A miniature valve automatically releases the pressure in the connecting element when coupling. However, this only works if one side is depressurized. The component with the pressure eliminator must be installed on the pressurized side.

    • What does "dead space free" mean?

      With so-called dead space-free connections, there is no escaping volume between the quick coupling and the plug when disconnected. The entire medium remains behind the shut-offs on the quick coupling and plug side. As a result, there is no leakage of a residue of the liquid that is between the two valves in standard connections. These low-leakage quick couplings contain KL in their item number.

    • Can quick couplings be used without the danger to mix up?

      You can use coded quick-release couplings and plugs, for example, to prevent the lines from being mixed up when changing connections on a control panel. The coding is done both in color and mechanically (different shapes), so that a wrong connection is impossible. To the coded quick couplings

Hoses

    • What does the specification 8 x 12 mm mean for hoses?

      The hose has an inner diameter of 8mm and an outer diameter of 12mm. The wall thickness of the hose is therefore 2mm.

    • What is the whiplash effect?

      When uncoupling conventional quick couplings, the released plug can fly out of the coupling like a bullet and whip the hose line connected to it around (whiplash effect). This potential hazard does not occur when using suitable safety quick couplings (self-venting couplings). To the self-venting quick couplings

Push-in connectors

    • Can a push-in connection be removed again?

      Yes, the push-in connections have a release ring. If you press this in the direction of the housing, the hose can be pulled out again. With each rmoval, the hose wears out heavily. For interfaces that have to be separated frequently, we always recommend using quick couplings.

Other products

  • What is the difference between a balancer and a spring balancer?

    A tool suspended from the spring balancer pulls back when released. With the balancer, the rope remains extended and the tool remains hanging at this height.

Ermeto fittings

    • What is the difference between series L and series S Ermeto fittings?

      Series S is designed for higher pressure ratings, while series L is more compact. With EO-2 and EO-PSR fittings, up to 800 bar (PN) is possible in series S and up to 500 bar (PN) in series L. Thanks to these high pressure ratings, series L can also be used where previously only series S was an option. This saves costs and assembly forces and helps in tight installation spaces. You can find more details in our technical section: Function of fittings

    • What is the difference between EO-PSR and EO-2?

      With the EO-PSR (progressive stop ring), the ring bites into the tube with two cutting edges and handles both sealing and holding functions. With the EO-2, these functions are separated: a retaining ring bites into the tube while an elastomeric sealing ring provides the seal. This makes the EO-2 fitting particularly leak-free and gas-tight. Both systems comply with the standards for 24° cutting ring fittings. More information: EO-PSR fitting and EO-2 fitting

    • How can I tell that an EO-2 fitting is fully assembled? Do I need to retighten it?

      Before assembly, there is a gap between the sealing ring and the retaining ring. Once this gap closes, assembly is complete. You can feel this as a distinct stop point and verify it by visual inspection; the tube end can remain in the fitting. Once the functional nut is wrench-tight, approximately 1/4 to 1/6 of a turn is sufficient. An EO-2 fitting does not need to be retightened, even after years of operation. Go to the EO-2 fitting

    • How often can I loosen and reassemble an EO-2 fitting?

      As often as you like. The sensitive sealing surface of the fitting does not wear or widen in the process. If the seal is damaged, the sealing ring can be replaced individually without cutting off the tube end. All replacement seals are marked to prevent mix-ups.

    • Can I use EO-2 functional nuts with my existing fitting bodies?

      Yes. The EO-2 functional nut fits all EO tube fittings. When converting from EO progressive ring or EO weld cone fittings, simply use EO-2 functional nuts with the same fitting bodies. In the functional nut, the sealing ring and retaining ring are captively joined, so they cannot be forgotten or installed the wrong way round. Go to Ermeto fittings

    • Which fitting is suitable for stainless steel tubes?

      For stainless steel, there is the EO progressive ring DPR, which is specially designed for the requirements of stainless steel. With the EO-2 fitting, the integrated assembly tool even allows stainless steel tubes to be assembled directly without an additional pre-assembly process. Both are available in series L and S. EO progressive ring DPR | Ermeto fittings in stainless steel

    • What is an O-Lok® fitting and what pressures is it suitable for?

      The O-Lok® fitting is a face-seal fitting consisting of a fitting body, a sleeve, a Trap Seal (elastomeric seal) and a nut. It achieves pressure ratings of up to 630 bar and complies with the standards SAE J1453 and ISO 8434-3. The tube end is given a 90° flange using the Parflange® process or is fitted with a solder sleeve. The seal should be inspected at every disassembly and replaced if necessary. Go to the O-Lok® fitting

    • What is a Triple-Lok® fitting?

      The Triple-Lok® fitting consists of just three parts: fitting body, sleeve and nut. The tube end is flared to 37° and clamped between the sealing seat and the sleeve. The seal is metal-to-metal, without an additional gasket. The fittings are designed for nominal pressures of up to 500 bar with a 4x safety factor and comply with SAE and ISO standards. Go to the Triple-Lok® fitting

    • Which tubes can I use with Triple-Lok®, and can I use inch tubing?

      Seamless or welded tubes, as well as seamless drawn, normalized tubes, are recommended. Usable materials include steel, stainless steel, copper and aluminium. The sealing surfaces in the sealing area must be round and smooth, free of scratches, impact marks, spiral machining marks, cracks or weld beads. Metric and inch tubes can both be used by simply exchanging the sleeve.

    • Where can I find assembly instructions for Ermeto fittings?

      Parker provides detailed tube assembly instructions. They cover, among other things, the assembly procedure, EO progressive ring PSR/DPR, EO-2, EO2-FORM, weld cone, O-Lok® and Triple-Lok®, the selection of the assembly method, and manual tube bending. Assembly instructions (PDF) | Go to the Correct tube assembly page