The requirements for the location of portable fire extinguishers is governed by the Australian standard AS2444. There are no simple rules to follow because each building is different, both in its layout, and fire risks. There are some general guidelines for locating fire extinguishers on the wall, and for the travelling, distance to get to a fire extinguisher.
AS2444 specifies that the base of the extinguisher must be mounted at least 10cm off the floor, and the top of it should be no more than 1.2m above the floor. Within those boundaries, you want to mount the fire extinguisher, so it is not knocked by cleaning equipment, or kicked by passers-by. Ideally located at roughly elbow height so the user can grab the handle easily. If damage due to people traffic is an issue, you should consider locating it in a fire extinguisher cabinet. There is no specific qualification for installing a fire extinguisher, it is, after all, just screwing in a bracket. But the position of the fire extinguisher within the building is best determined by a fire service company. If the fire extinguisher is not correctly located, you may fail any fire safety inspections on the premises!
Within the boundaries of travel distance to the fire extinguisher, the area protected, and fire risk type, it is important to locate the fire extinguisher, so it is not too close to the possible source of a fire. If the fire extinguisher is too close to the fire you will not be able to grab it to put the fire out! For cooking oil or fat fire risk (type F risk) the fire extinguisher must be at least 2m from the risk. For electrical switchboards a 5kg carbon dioxide is recommended, no closer than 2m to the switchboard. Ideally, the fire extinguisher is also located near an exit. Fire extinguishers cannot be hidden behind boxes, doors or curtains, they must be easily accessible and in view!