code/modules/plumbing/plumbers/_plumb_machinery.dm

/obj/machinery/plumbing	Basic plumbing object. It doesn't really hold anything special, YET. Objects that are plumbing but not a subtype are as of writing liquid pumps and the reagent_dispenser tank Also please note that the plumbing component is toggled on and off by the component using a signal from default_unfasten_wrench, so dont worry about it