The Swagelok alterative fuel service (AFS) ball valve was launched in 2004, and it has been well accepted in both alternative fuels and general industry markets. At the time of its release, the AFS ball valve was the only 1/2 in. ball valve certified to NGV 3.1, NGV 4.6 and ECE R-110 standards in the marketplace.
The NGV and ECE specifications. These specifications dictate pressure, temperature, cycle life, rebuild requirements and material compatibility for the AFS ball valve. The stringent, NGV 4.6, requires 40,000 cycles at rated pressure with a rebuild allowed at 16,000 cycles for the AFS ball valve.
While continuing to meet these important industry standards, Swagelok has modified the materials of construction of the AFS ball valve in response to end-user requests for more robust performance.
The AFS ball valve’s standard materials of construction include:
PTFE coating to the 316 stainless steel ball. Previously, the ball was uncoated. The PTFE coating provides a lower and more consistent torque over a number of cycles.
316 stainless steel processed to ASTM 276 for the stem material instead of 316 stainless steel processed to ASTM 479. ASTM 276, condition B, demonstrates better resistance to fatigue.
WL-21 assembly lubricant in place of WL-8 lubricant. WL-21’s composition is the same as WL-8’s, but better resists a condition called washout, where high-pressure surges essentially wash the lubricant out of the valve.
In addition, the pressure classification of the AFS valve for NGV 3.1 was increased from 3,600 psig (248 bar) to 4,500 psig (310 bar).
A rebuild kit is also available for customers that have AFS ball valves in service and wish to upgrade them.