Abstract: A residual life indicating system for a filter includes a main filter, a sampling filter, and a sensor. Both the main filter and the sampling filter receive an ambient gas meant to be filtered. The sensor connects to the sampling filter and senses the presence of a predetermined chemical in the gas that has been filtered by the sampling filter.

Abstract: A jerrycan holds liquid fuel. A cap for the jerrycan includes an air vent valve assembly having an umbrella-shaped check valve. The check valve is sensitive to a pressure differential between an interior of the jerrycan and the atmosphere. As fuel is dispensed from the jerrycan, a volume of an air chamber within the jerrycan increases, thereby decreasing the pressure in the jerrycan and creating a vacuum. The vacuum causes the rate at which fuel is dispensed from the jerrycan to decrease. The check valve dislodges when the pressure within the jerrycan becomes less than the pressure of the atmosphere and additional air is introduced into the jerrycan. The air fills the expanded volume of the air chamber, thereby increasing the pressure, eliminating the vacuum and causing the rate at which fuel is dispensed to increase.

Abstract: An air control assembly for a fuel burner having a combustion chamber and a nozzle includes a control device which controls the amount of air that flows into the burner and an assembly dependent on fuel pressure which actuates the control device. A fuel inlet path is provided for communicating fuel to the nozzle and a fuel return path is provided for communicating excess fuel away from the nozzle. The assembly dependent on fuel pressure includes a piston and rod device adapted for reciprocation in a piston chamber. A nozzle block is provided in which the piston chamber is defined and the nozzle is supported.