The figure shows how the “Typhoon” vacuum runners work. Left: the traces left by the burning die lubricant indicate the passage of the metal: entering from the bottom, it flows right and left to the vertical arms, and moves upwards to hit the trigger piston, being then diverted to rejoin the main streams. At the top, the configuration of the channels causes the metal to swirl with a
pattern resembling that of a typhoon (figure at top right), this rapid rotation of the liquid metal making it all the more certain that the metal does not enter the vacuum exhaust channel. When the valve closes, the very small amount of residual gas remaining in the valve is trapped, forming a pocket near the vacuum exhaust channel.
Typhoon valve runners guarantee reliable closure
The shape of the vacuum channels strongly affects reliability. Incoming metal at very high speed shows an atomized metal front. The front should be directed towards a “security zone” where it is imprisoned, and then should be conducted as late as possible near the evacuation piston. Such an arrangement can much reduce the incidence of failures.
Recommendation about managing the heat flux
VDS strongly recommends cutting the vacuum channels on the side opposite to that carrying the closure mechanism. This ensures that the heat removed from the liquid metal will mainly flow along paths that do not disturb this high precision mechanism.