BACK UP SEALING B006
The best mechanical seal in the world is going to fail some day. You need back up sealing if:
- The product you are sealing is dangerous. You’ll need some means of protecting people in the area.
- The product is costly.
- The product presents an environmental hazard if any of it leaks into the atmosphere, or on the ground.
- You produce a lot of batch operations and you cannot afford a failure in the middle of the batch.
The dual seal is the most logical of the back up choices. If the first seal fails the second seal takes over.
- The API (American Petroleum Institute) gland, shown below, is another choice.
- The disaster bushing (DB) will prevent leakage from spraying directly to the atmosphere.
- Although not a positive seal, the leakage will be directed down the drain pipe (Q) where it can be collected.
- Oil refineries often connect “Q” to a flare where volatile gases can be burned off.
- In some designs the disaster bushing (DB) is replaced with several rings of packing.
- Another function of the non-sparking disaster bushing is to help stabilize the shaft in the event of a bearing failure.