Automatic switching valve

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With continuing attention to the drawings wherein applied reference numerals indicate parts similarly hereinafter identified, the reference numeral 1 indicates a valve body for incorporation into a pressure system having multiple pressure sources such as CO.
sup.
2 tanks at 2 and 3 each equipped with standard outlet valves and controls (not shown).
First and second valve spools at 4 and 5 are each biased by first and second spool springs 6 and 7 in spring chambers 8 and 9.
Spool end chambers are at 10 and 11 each having an outlet at 12 and 13.
A spool end 4A and 5A permit at least a flow to the outlets.
Serving each spool is an inlet port at 14 and at 15 at tank pressure.
The spools 4 and 5 are each provided with lateral and axial bores 4B-5B to direct gas pressure from an inlet port 14-15 to a valve body passageway at 16 and at 17 respectively.
The passageways at 16 and 17 serve to direct a pressurized gas flow to end chambers 10 or 11 receiving the other spool.
Accordingly, each spool may, when open, direct a pressure flow to the end chamber of the other spool.
Outlets 12 and 13 deliver pressure flows in sequence to a separator valve chamber 20-21 to shift a separator spool 22 to isolate the outlets 12 and 13 from one another.
An outlet line at 23 is provided with a pressure regulator at 24 for controlling pressure to an outlet such as a soft drink carbontating device not shown.
In operation, with the spools positioned as in FIG.
1, a pressurized gas flow from cylinder 2 enters inlet port 14 and is directed by valve spool passages 4B to passageway 16 and hence to end chamber 11 of spool 5.
Spool 5 is accordingly lifted from its seated position against the action of spring 7 to allow an unrestricted pressure flow out outlet 13, through repositioned separator valve spool 22 and utlimately to outlet line 23.
As cylinder 2 pressure diminishes, the pressure in end chamber 11 will fall below the value necessary to fully compress spring 7 and the latter will shift spool 5 downward toward a seated position