QF2A cylinder valve
QF2A cylinder valve
O-ring Seal Valves
Elements
Two-piece spindle, soft seated, brass body
Description
These valves have a non-rising upper spindle & threaded lower spindle. It uses O-ring/s to create a seal around the upper spindle. The top spindle is designed to fail first, allowing valve maintenance & package content recovery in the event of a failure, even when the cylinder is full. These valves come in key, toggle, handwheel & handle operation.
Handwheel operation
The upper spindle is fitted to a handwheel to operate the valve by hand. This restricts imparting of high torques by the user to operate it, preventing damage to the operating mechanism & facilitating high cycle life.
Key operation
The upper spindle is usually manufactured from Stainless steel as the valves are expected to withstand high torques in the field.
Application
These valves are easier to operate than packed valves due to absence of packing load on the upper spindle & hence used for a wide range of pressure & non-corrosive gas applications where low torque operation is desired.
Diaphragm Seal Valves (QF2A cylinder valve)
Elements
Handwheel operated, two-piece spindle, soft seated
Common valve body materials
Stainless steel, Brass
Description
These valves use diaphragms for gland sealing which gives the valves superior leak integrity. The gland nut threads into the valve body & clamps the outer edges of the diaphragms against a ledge in the valve body to form a seal. The lower spindle assembly is non-threaded & non-lubricated, encased in a spring which forces it away from the seat when the valve is opened. The upper spindle is threaded into the gland nut. The valve opening is restricted by the stroke of the diaphragm, limiting the flow through the valve.
Application
The design is highly suitable for toxic, pyrophoric & high purity gas. Due to high torque required to close the valve by overcoming cylinder pressure X area of the diaphragm plus the spring force, the use of these valves is limited to cylinder pressure up to 200 bar.
