Posted By George Wedgwood
An annual inspection is recommended by Croners 'Guide to Fire Safety' but I would advise more frequent examinations depending on the siting of the appliances - e.g. if kept in damp places, they should be given thorough examination which includes the body integrity - to minimise any danger that perforation has occurred or rusting/corrosion is taking place. The point here is specifically made in respect of gas cartridge operated devices, which only suffer stress when discharged - this can occasionally blow out the bottom if coroded! If they are sited in public places, they may be subject to tampering and again a more frequent inspection may be necessary. George

Posted By David Thomas
Stuart
BS5306 Part3 2000 Clause 4 is the technical reference.
The frequency of inspections should be not less than monthly unless circumstances warrant more frequently.
So you are required to check that the extinguishers are "in place" (ie not proping open a fire door) and that they have not been discharged.
I carry out the former on a daily basis - assisted by large vertical luminous sign marked MISSING - on my regular building walks. It is good practice to carry out a monthly physical check of the gauges to ensure all the same reading. Even if one hasnt been discharged the contents may have leaked or evaporated.
Also check the pins are still in situ, people/bags/goods dragged past quite often move the pins, a loose or missing pin could lead to an inadvertant discharge.
All extinguishers should be subject to an annual check by a "qualified" person, and it shouldnt cost too much if you use a reputable small concern, preferably by recommendation.

dave