F24V30/00	7	Apparatus or devices using heat produced by exothermal chemical reactions other than combustion	F24V30/00	F24V30/00		1291
F24V40/00	7	Production or use of heat resulting from internal friction of moving fluids or from friction between fluids and moving bodies	F24V40/00	F24V40/00		736
F24V40/10	8	the fluid passing through restriction means	F24V40/10	F24V40/10		109
F24V50/00	7	Use of heat from natural sources, e.g. from the sea	F24V50/00	F24V50/00		281
F24V99/00	7	Subject matter not provided for in other main groups of this subclass	F24V99/00	F24V99/00		526
