A high pressure valve (100, 200, 300) comprising: a housing (40, 50, 30) having a chamber, a first port configured to allow fluid to flow therethrough, a second port configured to allow fluid to flow therethrough, the chamber providing fluid communication between the first port and the second port; a pin movable within the chamber between an open position in which the first port and the second port are in fluid communication and a closed position in which the first port and the second port are not in fluid communication; a back-up ring that guides the pin, the back-up ring having a concave geometry on its lower face; a seal having an inner diameter through which the pin passes and an end surface with a spherical geometry configured to match the concave surface of the back-up ring, wherein high pressure in the chamber causes the seal to deform inwardly against the pin and to flare an outer diameter wall of the back-up ring outwardly; a lever having a first end coupled to the pin and a second end, the lever having a pivot point that is pivotally secured to the housing; a variable force generator connected to the second end of the lever and configured to move the pin between the open position and the closed position; and a controller coupled to the variable force generator, the controller being configured to adjust a force applied to the second end of the lever by the variable force generator to control the movement of the pin between the open position and the closed position, wherein the high pressure valve is configured to operate at a pressure of at least 137.90 MPa (20,000 psi) as measured in the chamber. a housing (40, 50, 30) having a chamber, a first port configured to allow fluid to flow therethrough, a second port configured to allow fluid to flow therethrough, the chamber providing fluid communication between the first port and the second port; a pin movable within the chamber between an open position in which the first port and the second port are in fluid communication and a closed position in which the first port and the second port are not in fluid communication; a back-up ring that guides the pin, the back-up ring having a concave geometry on its lower face; a seal having an inner diameter through which the pin passes and an end surface with a spherical geometry configured to match the concave surface of the back-up ring, wherein high pressure in the chamber causes the seal to deform inwardly against the pin and to flare an outer diameter wall of the back-up ring outwardly; a lever having a first end coupled to the pin and a second end, the lever having a pivot point that is pivotally secured to the housing; a variable force generator connected to the second end of the lever and configured to move the pin between the open position and the closed position; and a controller coupled to the variable force generator, the controller being configured to adjust a force applied to the second end of the lever by the variable force generator to control the movement of the pin between the open position and the closed position, wherein the high pressure valve is configured to operate at a pressure of at least 137.90 MPa (20,000 psi) as measured in the chamber.