When it comes to fire sprinkler inspections, it is best to have them inspected annually, at minimum. If you want to be NFPA compliant, in particular NFPA 25 compliant, you want to be inspecting at various intervals as fire sprinkler systems are made of varying parts. You could do so: * Monthly -- primarily for gauges. * Quarterly - For a more extensive inspection. * Annually - can focus on pipework for the system. * Every Five years - and lastly, to thoroughly inspect all internal pipework relating to the system.