The vented port-cap includes a check-valve, which admits air into the barrel of the hydrant when the pressure inside is lower than the pressure outside. After an inspection of the hydrant, the hydrant can be left to drain by itself, even though the port-cap has been replaced and tightened.
대표청구항▼
The invention claimed is: 1. Port-cap for a fire-hydrant, wherein: the port-cap is so structured that the port-cap can be fastened to, and can close-off, a hose-port of a fire-hydrant; the port-cap is so structured that the port-cap can be unfastened from, and removed from, the hose-port; the port-
The invention claimed is: 1. Port-cap for a fire-hydrant, wherein: the port-cap is so structured that the port-cap can be fastened to, and can close-off, a hose-port of a fire-hydrant; the port-cap is so structured that the port-cap can be unfastened from, and removed from, the hose-port; the port-cap includes an air-hole, which, when the port-cap is fastened to the hose-port, connects the interior of the barrel of the fire-hydrant to the outside atmosphere; the port-cap includes a check-valve; the check-valve is arranged in the port-cap to open the air-hole when the atmospheric pressure outside the fire-hydrant exceeds the pressure inside the barrel of the fire-hydrant; the check-valve is arranged to close the air-hole when the pressure inside the barrel exceeds the pressure outside; and the port-cap includes an air-hole-cap, which is arranged to cover the air-hole in the port-cap. 2. Port-cap of claim 1, wherein: the check-valve includes check-valve-components, being a ball, a ball-seating, a spring, and a check-valve body; the check-valve body is arranged to hold the spring urged against the ball, and the ball thereby urged against the ball-seating; and the check-valve body is fast with the port-cap body. 3. Port-cap of claim 2, wherein: the port-cap includes a port-cap body, having a hollow open-ended skirt-portion; a female screw-thread is formed inside the skirt-portion, whereby the port-cap can be screwed onto a corresponding male screw-thread on the hose-port of the fire-hydrant; and all the check-valve-components are entirely contained within the skirt-portion of the port-cap. 4. Port-cap of claim 3, wherein all the check-valve-components are entirely contained within the skirt-portion of the port-cap, to the extent that, when the port-cap is viewed in side elevation, no check-valve-component, nor any portion thereof, is visible protruding outside the skirt-portion. 5. Port-cap of claim 2, wherein the ball-seating is machined directly into the metal of the port-cap body. 6. Port-cap of claim 2, wherein: the ball, the ball seating, the spring, and the check valve body are all of metal; the ball-seating is machined directly into the metal of the check valve body; and the check-valve-components form a self-contained pre-assembled sub-assembly, having been pre-assembled before the check valve is made fast to the port-cap body. 7. Port-cap of claim 2, wherein the check-valve body is threaded, and is screwed to a corresponding thread in the port-cap body. 8. Port-cap of claim 1, wherein the check-valve is structured to open when the atmospheric pressure outside the fire-hydrant exceeds the pressure inside the barrel of the fire-hydrant by less than about one psi. 9. Port-cap of claim 1, wherein the check-valve is structured to open when the atmospheric pressure outside the fire-hydrant exceeds the pressure inside the barrel of the fire-hydrant by more than about ? psi. 10. Port-cap of claim 1, wherein, the air-hole-cap includes a tortuous air passage. 11. Apparatus including the port-cap of claim 1 in combination with a dry-barrel fire-hydrant. 12. Apparatus of claim 11, wherein: the fire-hydrant includes a main-valve and a drain-valve; and the fire-hydrant includes a valve operator, for operating the hydrant between a main-valve-open/drain-valve-closed condition and a main-valve-closed/drain-valve-open condition. 13. Procedure for modifying a fire-hydrant having a port-cover, including removing the port-cover, and replacing same with a port-cap that falls within the scope of claim 1. 14. Procedure for inspecting a fire hydrant, being a fire hydrant that falls within the scope of claim 11, wherein: an operator unscrews the port-cap from the hose-port of the fire-hydrant; the operator then opens the fire-hydrant, and inspects the flow of water therefrom; the operator then shuts off the flow of water from the fire-hydrant; the operator then immediately replaces the port-cap, including screwing and tightening the port-cap back onto the hose-port; whereby, as a volume of water drains from the barrel of the fire-hydrant, a compensating volume of air enters the barrel through the air-hole in the port-cap; whereby the operator can walk away and leave the fire-hydrant to drain by itself, with the port-cap replaced. 15. Procedure of claim 14, wherein: the operator, having replaced the port-cap, listens for the hissing sound of air entering the barrel through the air-hole; and responsively to having heard the hissing sound, the operator walks away and leaves the fire-hydrant to drain by itself, with the port-cap replaced.
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