Why do pistons after 6 years of storage do not work anymore?

Question: Do you have a distributor in the USA. You supplied gas piston part # SDB8Z2060108Z2N 157234 49/04 to a UK gun safe manufacturer, to support the top lids of their Escritoire safes when opened. These pistons have failed & no longer hold the lids up. We need to replace these and request your assistance in locating 7 of these. These safes have been in inventory & crated for approx 6 years and the lids have been closed, why would pistons be failing? Answer: Thank you for your interest in these gas springs. In order to have new ones made, and only 7 pieces, the estimated cost per gas springs will be around 100-200 euros  (ex-works) Not sure if you want to spend that amount of money? Reason: these parts are usually manufactured per 100 pieces. You can get a better deal when you would purchase from the manufacturer of the escritoire safes direct. However if further interested we can quote you also with an exact price. Failure can be due to un proper installation, a leak of gas over time or when you have stored the gas springs wrong, the interior parts of the gas spring were not lubricated, as it was stored reverse up,  I  would assume that due to too long storage, the parts are not anymore working properly. Usually storage is limited to 2 years (if stored in ideal conditions)   1. Should a Gas Spring be mounted "Rod up" or "Rod down"? "Rod down" is the preferred orientation for mounting a Gas spring. An optimum design would permit the support to be oriented rod down through its entire actuation. There are several reasons for this: In order to achieve the damping or "cushion" at the end of the Gas spring's stroke, the piston assembly inside of the Gas spring must travel through oil at the end of the stroke. "Rod down" orientation ensures that the oil is in the proper location for full damping to occur. "Rod down" orientation ensures that the rod and sealing components are lubricated with every stroke of the Gas spring. This reduces seal wear and helps to inhibit corrosion. 2. What is the expected life of a Gas spring? When estimating the life of a Gas spring, one must first determine how much force the support can lose before the application becomes unacceptable. The time it takes to lose this amount of force is considered to be the life of the support. All Gas springs lose output force over time. The rate at which force loss occurs varies greatly between application and manufacturer. Many factors affect the rate of force loss, such as: size of the support, orientation, amount of cycles, ambient temperature, vibration, and the geometry of the application and time(cycle time). Considering all of the variables, it is very difficult to estimate life accurately without actual testing on the application. As noted above, all Gas springs will lose output force over time. It is recommended that the gas springs be periodically checked to ensure that they are functioning as intended. This inspection should be implemented as part of a planned maintenance activity, if possible. 3. How can a designer ensure the longest life for a Gas spring in an application? Orient the support "rod down". As explained above, this will continually lubricate the seal and rod and reduce permeation through the seal. Utilize the largest gas volume possible in the support. In general, use the minimum stroke required with the largest body possible. In a support with a large gas volume, small gas losses are imperceptible in the output force. The temperature of the Gas spring should remain well within the temperature limits. If temperature extremes will be encountered, it should be for a short duration and the support should not be cycled while at the extremes. Utilize the highest force Gas spring possible that still provides acceptable handling loads for the application. This will allow for some force loss without the loss of function of the application. Avoid side load, vibration, contamination and damage to the rod. Provide multiple mounting locations so that the support can be moved to accommodate for force loss as the support ages.   final reply from the customer: Thank you for your swift response. Great customer service, I’m very impressed. Yes that price is a little steep, I will contact the manufacturer of the escritoire safes and take it from there.