From:
http://www.alliantpowder.com/getting_started/safety/storage_handling.aspx
Considerations For Storage Of Smokeless Powder
Smokeless powder is intended to function by burning, so it must be protected against accidental exposure to flame, sparks or high temperatures.
For these reasons, it is desirable that storage enclosures be made of insulating materials to protect the powder from external heat sources.
Once smokeless powder begins to burn, it will normally continue to burn (and generate gas pressure) until it is consumed.
D.O.T. approved containers are constructed to open up at low internal pressures to avoid the effects normally produced by the rupture or bursting of a strong container.
Storage enclosures for smokeless powder should be constructed in a similar manner: 1. Of fire-resistant and heat-insulating materials to protect contents from external heat. 2. Sufficiently large to satisfactorily vent the gaseous products of combustion which would result if the quantity of smokeless powder within the enclosure accidentally ignited.
If a small, tightly enclosed storage enclosure is loaded to capacity with containers of smokeless powder, the enclosure will expand or move outwards to release the gas pressure - if the powder in storage is accidentally ignited.
Under such conditions, the effects of the release of gas pressure are similar or identical to the effects produced by an explosion.
Hence only the smallest practical quantities of smokeless powder should be kept in storage, and then in strict compliance with all applicable regulations and recommendations of the National Fire Protection Association (scroll down to read).
Recommendations For Storage Of Smokeless Powder
STORE IN A COOL, DRY PLACE. Be sure the storage area selected is free from any possible sources of excess heat and is isolated from open flame, furnaces, hot water heaters, etc. Do not store smokeless powder where it will be exposed to the sun's rays. Avoid storage in areas where mechanical or electrical equipment is in operation. Restrict from the storage areas heat or sparks which may result from improper, defective or overloaded electrical circuits.
DO NOT STORE SMOKELESS POWDER IN THE SAME AREA WITH SOLVENTS, FLAMMABLE GASES OR HIGHLY COMBUSTIBLE MATERIALS.
STORE ONLY IN DEPARTMENT OF TRANSPORTATION APPROVED CONTAINERS.
Do not transfer the powder from an approved container into one which is not approved.
DO NOT SMOKE IN AREAS WHERE POWDER IS STORED OR USED. Place appropriate "No Smoking" signs in these areas.
DO NOT SUBJECT THE STORAGE CABINETS TO CLOSE CONFINEMENT. STORAGE CABINETS SHOULD BE CONSTRUCTED OF INSULATING MATERIALS AND WITH A WEAK WALL SEAMS OR JOINTS TO PROVIDE AN EASY MEANS OF SELF-VENTING.
DO NOT KEEP OLD OR SALVAGED POWDERS. Check old powders for deterioration regularly. Destroy deteriorated powders immediately.
OBEY ALL REGULATIONS REGARDING QUANTITY AND METHODS OF STORING. Do not store all your powders in one place. If you can, maintain separate storage locations. Many small containers are safer than one or more large containers.
KEEP YOUR STORAGE AND USE AREA CLEAN. Clean up spilled powder promptly. Make sure the surrounding area is free of trash or other readily combustible materials.
