AVM is the only company to build gas springs with a multi-lobe seal. The seal provides superior durability in dirty, wet environments over a standard lip seal but does require a more complex manufacturing process.
Gas springs with lip seals can be manufactured complete and charged last by blowing gas past the seal, this is not possible with a Multi-lobe seal requiring the gas spring be charged during the assembly process. The benefits of providing the customer a more durable seal make this a worthwhile proposition for AVM but there is a small cost disadvantage and so AVM also offers gas springs with a lip seal for standard applications (see the lip seal web page for more information).
If your application subjects the gas spring to severe environmental conditions a Multi-lobe seal will perform better than a lip seal gas spring. When developing the force required from the gas spring for your application, one should plan on a 1-2 % force loss per year. All gas springs manufactured today will loose some force over time because the gas molecules permeate through the rubber seal material regardless if it is a Multi-lobe or lip seal. The amount of force lost depends on a number of factors, and this should be calculated into the design to ensure the gas spring still lifts or balances the loads several years down the road.
Avm offers dynamic dampening with both Multi-lobe and lip seal designed gas springs, dampening can also be provided in some applications by varying the oil volume inside the gas spring.
Temperature plays a big part with gas springs. Output force will increase as the temperature rises and decrease as it drops. Gas springs function by utilizing compressed nitrogen gas to provide the force to extend the shaft via a differential in surface area of the piston. It is these gases that are affected by the temperature changes. In all applications, one must use a gas spring with enough force at the high end of the temperature range.
|Cylinder||Heavy gauge steel body; painted and cured to a glossy finish.|
|Piston Rod||Chromium-plated or Black Nitride hardened steel, precision-ground and highly polished.|
|Piston Assembly||Self-cleaning design automatically opens during each compression stroke to keep the piston area free of contaminants. Not offered by all manufacturers.|
|Sealing System||This is the area where most manufacturers differ in their approach. AVM uses a patented Triple-Lobe Rubber Seal, as well as a Rubber O-Ring Piston Seal.|
|Seal Backup System||Teflon ring, functions as a backup to the seal system, unique to AVM. Prevents seal wear.|
|Temperature Compensation||Optional feature, this module provides for an increase in the force when the temperature drops below approximately 40 F enabling the use of lower forces at room temperatures to provide easier closing efforts.|
|Nitrogen Gas Charge||Gas springs are charged with nitrogen most often to 1500 psi, but not more than 2500 psi. It does not react with any of the internal components. The amount of charge varies from 1/3 gram in the smallest springs to about 24 grams in the largest. Nitrogen is inert and is not flammable.|
|Glycol Fluid||Lubricant for internal components. Also provides dampening to slow down movement of liftgate just prior to full open. This is a high viscosity index synthetic oil with a pour point of -70 F.|