Originally Posted by avionstream
Thanks, that helps a lot. I bought a bigger than stock extinguisher and have a good place to mount it horizontally next to the door. Is shaking or turning it over periodically really necessary? Jim
If you are ever present when the fire inspector shows up you might observe that he reads the fire ext. placard to determine if it's still within the date-of-service/expiry... and if it is... then he turns it upside-down and gently "whacks" it with a hit from a rubber mallet... to knock the dry powder loose within the container.
Merely turning it upside down is not really adequate. The intent to to dislodge powder which becomes "packed" from inactivity. Dry chemical powders become almost SOLID from the vibration of driving down the road as the powder becomes packed. ( I once disassembled a large commercial dry-powder extinguisher when it's gauge read zero. The internal pickup/discharge tube was packed so firmly with powder it required me to jam a metal rod down the tube to dislodge the packed extinguishant. The main charge was a solid cylinder until I whacked it with a rubber mallet, whereupon it instantly returned to a loose-powder.
Lubricate the seals/O-rings with WD-40, reassemble the valve, re-charged with 150 psi of dry nitrogen (CO2 will also work if you have a welding setup)...and VOILA!.... it's returned to service (on my private property.)
Don't dent the soft container...but give it a good whack (on the firm edge of the cylinder-bottom/rim) while holding it upside down, at regular intervals ...in an RV, at the beginning of each trip during the departure-inspection would be a good rule, IMO.