A check valve for cryogenic fluid includes: a valve body which is formed to have an inlet and an outlet open at both ends thereof, a valve seat which is formed inside the valve body to communicate with the inlet; a disk which is pivoted up and down at the upper end thereof about a pivot axis provided in the valve body to open and close the valve seat; and a sealing member which is made of a metal material shrinkable by cryogenic fluid introduced through the inlet, is provided in the circumferential direction of the valve seat, and when the disk closes the valve seat, is brought into close contact with the edge portion of the disk to produce sealing effects.

A check valve includes a housing having an upstream end and a downstream end. The housing includes a throughbore extending from the upstream end to the downstream end, an outer surface extending from the upstream end to the downstream end, and an access port extending from the outer surface to the throughbore. The access port includes an internal annular shoulder and one or more recesses extending into the internal annular shoulder. In addition, the check valve includes a valve seat disposed in the throughbore of the housing. Further, the check valve includes a check valve assembly at least partially disposed in the access port. The check valve assembly includes a flapper extending into the throughbore and configured to pivot relative to the valve seat between an open position spaced apart from the valve seat and a closed position engaging the valve seat. The check valve assembly also includes one or more flapper alignment members pivotally coupled to the flapper, wherein each flapper alignment member is slidingly seated in one of the recesses in the internal annular shoulder of the access port to align the flapper with the valve seat in the throughbore.

A swing check valve is disclosed, the swing check valve comprising a housing; a disc; and a sealing arrangement between the housing and disc. The sealing arrangement comprises a flexible disc seat; and a metallic body seat. The metallic body seat comprises an engagement surface for engaging the flexible disc seat, the engagement surface includes a raised portion for engaging the flexible disc. In an embodiment the metallic body seat comprises an engagement surface for engaging the disc seat, the engagement surface comprising a first portion for engaging a flexible elastomeric portion of the disc seat and a second portion for engaging a metallic portion of the disc seat after compressing the flexible elastomeric portion.

A blocking valve has an outer valve body housing a weighted paddle, the weighted paddle having a narrow upper portion with a hitch groove and a wider lower portion, the weighted paddle rotatable around a horizontal pivot, the weighted paddle to lie in a horizontal position during an active flow of liquid and to rotate to a vertical position with the upper portion above the lower portion when the flow of liquid is stopped, and a locking mechanism to engage with the hitch groove to lock the weighted paddle into a vertical position and to block the active flow of liquid when the active flow of liquid is resumed.

In accordance with at least one aspect of this disclosure, a system includes a first wire configured to electrically connect a valve stop to a voltage source, a second wire configured to connect a valve pin to a negative terminal of the voltage source, such that the valve stop, and a valve flap operatively connected to the valve pin are configured to create a closed valve circuit when the valve flap is in a fully open position with the valve flap contacting the valve stop, and an open valve circuit when the valve flap is not in the fully open position. A meter is operatively connected to measure an electrical characteristic of the valve circuit to determine when the valve flap is in the fully open position based on an open/closed status of the valve circuit.