A system comprising: an agent cylinder, comprising a valve port and a check valve in the valve port; and a gauge tool having an inlet arranged to removably connect to the valve port of the agent cylinder having the check valve, the gauge tool comprising: a valve body extending along a first axis between a first valve body end and a second valve body end, the valve body defining a valve seat, the inlet, and an outlet extending along a second axis that is disposed transverse to the first axis, wherein the inlet extends through the valve seat along the first axis; a valve member movably disposed within the valve body, the valve member extending between a first valve member end and a second valve member end along the first axis, wherein the valve member includes a protrusion that extends from the first valve member end and extends into the inlet; and a drive member connected to the second valve member end, responsive to actuation of the drive member relative to the first axis, the valve member is movable between a first position that inhibits a fluid flow between the inlet and the outlet and a second position that facilitates the fluid flow between the inlet and the outlet; configured such that the fluid flow is facilitated between the inlet and the outlet of the gauge tool while the protrusion of the valve member engages the check valve in the valve port of the agent cylinder; and configured such that the fluid flow is inhibited between the inlet and the outlet of the gauge tool while the protrusion of the valve member is spaced apart from the check valve in the valve port of the agent cylinder. an agent cylinder, comprising a valve port and a check valve in the valve port; and a gauge tool having an inlet arranged to removably connect to the valve port of the agent cylinder having the check valve, the gauge tool comprising: a valve body extending along a first axis between a first valve body end and a second valve body end, the valve body defining a valve seat, the inlet, and an outlet extending along a second axis that is disposed transverse to the first axis, wherein the inlet extends through the valve seat along the first axis; a valve member movably disposed within the valve body, the valve member extending between a first valve member end and a second valve member end along the first axis, wherein the valve member includes a protrusion that extends from the first valve member end and extends into the inlet; and a drive member connected to the second valve member end, responsive to actuation of the drive member relative to the first axis, the valve member is movable between a first position that inhibits a fluid flow between the inlet and the outlet and a second position that facilitates the fluid flow between the inlet and the outlet; configured such that the fluid flow is facilitated between the inlet and the outlet of the gauge tool while the protrusion of the valve member engages the check valve in the valve port of the agent cylinder; and configured such that the fluid flow is inhibited between the inlet and the outlet of the gauge tool while the protrusion of the valve member is spaced apart from the check valve in the valve port of the agent cylinder. a valve body extending along a first axis between a first valve body end and a second valve body end, the valve body defining a valve seat, the inlet, and an outlet extending along a second axis that is disposed transverse to the first axis, wherein the inlet extends through the valve seat along the first axis; a valve member movably disposed within the valve body, the valve member extending between a first valve member end and a second valve member end along the first axis, wherein the valve member includes a protrusion that extends from the first valve member end and extends into the inlet; and a drive member connected to the second valve member end, responsive to actuation of the drive member relative to the first axis, the valve member is movable between a first position that inhibits a fluid flow between the inlet and the outlet and a second position that facilitates the fluid flow between the inlet and the outlet; configured such that the fluid flow is facilitated between the inlet and the outlet of the gauge tool while the protrusion of the valve member engages the check valve in the valve port of the agent cylinder; and configured such that the fluid flow is inhibited between the inlet and the outlet of the gauge tool while the protrusion of the valve member is spaced apart from the check valve in the valve port of the agent cylinder.