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Hahn Gasfedern: Questions about products

Questions about products

Here we answer frequently asked questions about our gas springs, services, ditributors and technical specifications. This page lives from your input and is constantly being up-dated. Please send your questions.

1) How does a gas spring work?
For more information about the function of gas springs, please visit our website.

2) How long is the delivery time at HAHN?
The delivery time for HAHN standard springs in small volumes is around 1 week. For larger quantities and special productions, the delivery time is considerably longer. Please ask your contact partner at HAHN.

3)Can a fully functioning gas spring be returned?
Because HAHN manufactures its springs to order, it is not possible to return gas springs.

4) What should I do if I have a complaint?
If you have a complaint, please contact the person who has been dealing with your order, who will give you an RMA number (event number). Send us your gas spring with a delivery slip, which should give the RMA number and the reason for the complaint. We will deal with your concern as quickly as possible.

5) Why does the serial number / customer order number (CO number) change?
Our CO numbers are sequential, because of the wide range of gas springs that we offer. A number CO is given for each order. You will find the CO number on your gas spring.

6) What are gas springs filled with?
Gas springs are filled with nitrogen, which prevents oxidation inside the gas spring.

7) How high is the pressure in a gas spring?
The pressure is approved up to a certain maximum value, depending on model series. In the product range offered by HAHN, the filling pressure is between 10 and 160 Bar.

8) What does 'progression' mean?
Pushing in the piston rod reduces the volume in the cylinder and the gas is compressed. The associated increase in force is described as progression. This depends on the diameter of the piston rod and the volume of the cylinder.

9) Is there a difference between a gas spring's extension and compression force?
Yes. The contact between the seal and the piston rod and the piston on the inside of the pressure pipe creates a frictional force. This frictional force acts against the direction of movement of the piston rod. This means that, on extension, the gas spring force is reduced by the friction. To push the piston rod in, a force increased by the friction must be applied.

10) Does a gas spring need to be maintained?
No, gas springs are maintenance-free. To ensure that the function of the spring remains unimpaired, dirt on the piston rod can be removed with plain water.

11) Does a gas spring need to be protected from dirt?
It is not absolutely essential to protect a gas spring from dirt. However, it is recommended that a gas spring that is exposed to extreme dirt is protected, for example, with a wiper ring or a protective tube. The working life of the gas spring can be extended in this way. A wiper ring stops dirt getting inside the gas spring. If the conditions are particularly harsh (e.g. with road sweeping machines), you can protect the piston rod against external factors and thus against possible damage using a protection tube.

12) Within what temperature range can gas springs be used?
The temperature range within which a gas spring can be used depends on its seal. HAHN has gas springs for use at temperatures between -40° and +200°C. You will find more information about HAHN's LT gas springs and HT gas springs in our HT/NT gas springs flyer.

13) Do HAHN gas springs comply with RoHS requirements?
Yes. Our gas springs are all REACH-compliant and manufactured in accordance with the RoHS directives. In addition we are certified under DIN ISO 9001 and DIN ISO 1400.

14) How do I find my personal contact partner?
Our sales partners throughout the world are listed on our website. You can reach your personal contact partner for Sales Germany via our head office (tel.: +49(0)711 936 705 – 50, e-mail: info@hahn-gasfedern.de).

15) What is the right way to install gas springs?
Gas springs should always be installed with the piston rod downward, and tension springs with the piston rod upward. If gas springs are installed incorrectly, the seal is not in the oil, which increases the risk of the stick-slip effect, which in turn means that the gas spring is more likely to fall out faster. In addition, a gas spring which is installed the wrong way round has no end position damping. One way of avoiding this is to use gas springs with grease chamber. Here, installation is also possible the other way round, but here too there is no end position damping of the gas spring. You will find details about this in our Technical Regulations.

16) What is the right way to store gas springs?
Gas springs are not intended to be kept in stock. If gas springs are stored, the procedure is the same as for installing gas springs. Gas springs should be stored with the piston rod downward, and tension springs with the piston rod upward. You will find more information in our Technical Regulations.

17) Can storage damage occur?
If they are stored correctly (see "What is the right way to store gas springs?"), no pressure losses are likely, but the products should not be stored for longer than 1 year. The first time the gas springs are used (moving the piston rod in/out) after an extended period of non-use, a stick-slip effect may occur. In this case, more force is needed to move the piston rod in or out. If the gas springs are not stored correctly, the sticking of the seal to the piston rod can mean that the seal is damaged when the gas spring is used.

18) Can a stick-slip effect also occur with gas springs?
Using the springs for the first time (moving the piston rod in/out) can cause a stick-slip effect), and so more force is needed to move the piston rod in or out. This stick-slip effect describes the jerky sliding of solid bodies moved against each other. This effect can always occur if the static friction is greater than the dynamic friction.

19) What is the maximum stroke?
The maximum stroke is determined by the model series and the application. In addition to the standard strokes (see data sheets), it is possible to adapt the stroke lengths individually to your application and requirements. Our Internal Sales and our experienced Internal Technical Support team will be happy to advise you and support you with the design of the gas springs for your application.

20) What does a gas spring weight?
The weight of a gas spring is between 20 g and 10 kg.

21) Can a gas spring be repaired?
Whether a gas spring can be repaired depends on what is faulty about the spring. If your gas spring is no longer working properly, you can submit a complaint about your spring. You will find further information about submitting a complaint under Question 4. If you have any further questions, please contact the person dealing with your order.

22) What colours can I order my gas springs in?
The HAHN standard gas springs are painted in black. However, on request, cylinder tubes can also be galvanized or made in steel or stainless steel (V2A (AISI 304) and V4A (AISI 316)). In addition, our gas springs are also available on request in other colours. And if you are looking for something personalized, you can adapt your springs to specific look using our DipPrint process.

23) Can gas springs also be used as end stops?
Gas springs, tension springs and dampers can be used as end stops if the nominal force does not exceed +30% (no overstretching of compression of the product). That means that the products may only be subjected to compressive or tensile loading with their nominal force of +30%. Mechanical stops should be attached in addition, especially with high forces, to prevent compression / overstretching of the product.

24) Is there a length tolerance?
Yes. The tolerance is +/-2mm for piston rods and cylinder tubes.

25) What extension forces are possible?
HAHN supplies gas springs with extension forces of 5N-10.000N, depending on model series.

26) Can the extension force be adjusted?
Yes, if your gas spring has a valve, the gas spring can be refilled.

27) Do HAHN gas springs comply with the food hygiene requirements?
Yes. For special applications, e.g. in the medical industry, the chemicals and food industry and in ship and yacht construction, HAHN makes gas springs from high-quality stainless steel. These springs are rust-free and resistant to chemicals. As an option, an oil complying with FDA regulations can be used.

28) Does HAHN also supply gas springs to private customers?
HAHN Gasfedern supplies both private and industrial customers. HAHN supplies individual gas springs to customer specifications whether they order 1 spring or 1,000.

29) What is the custom tariff code for all HAHN products?
The custom tariff code for all HAHN products is 83024900.

30) CE marking
Gas Spring are generally not obligated to the CE marking. Our gas springs do not fall under the the machinery guideline 98/37/EG or 2006/42/EG

We will gladly answer any questions, see our contact form