MIlkboy,
The end user, seller and buyer need to all have an interest in the success of a seal. A guarantee takes the burden off the end user. The seller may or may not care and the manufacturer should care.
Manufactuer is either foolish or trying to keep out the compition if providing a guarrantee for anything other than workmanship and materials. Things they have direct control.
In determining if it will work for 2 years, a design a feasibilty study should be conducted with all parties invovled. During this study most if not all of the potential failure mechansims can be determine. Then the discussion should turn to how the seal will react to the failure methods. This can help provide why you need a new seal or what you need from the seal.
A properly functioning seal is a sign of a well maintain and aligned machine and process.
It may be a more realistic goal to get 4 times the service from the existing device than a "2-year target". Often times a small amount of maintenance will greatly extend component life in rotating equipment.
Cheers,
Mecoman
