Shasta systems include an Argon pathway configuration that allows argon consumption to be minimized at the end of a synthesis run. This is achieved by using a manual 3‑way valve in combination with a secondary argon solenoid that is automatically controlled by the software.
Default Configuration (Recommended)
The system is designed so that argon is continuously supplied to the bottle pathways while the instrument is idle.
To achieve this:
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The manual 3-way valve is set to Bypass (Port #2) by default at the factory
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In this position, argon is supplied to the bottle pathways without requiring software-controlled solenoid actuation
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This is the default and recommended configuration for most customers
Continuous argon pressurization helps maintain positive pressure in the bottle pathways and protects reagent integrity.
How the Argon-Saving Feature Works
Shasta systems use high-precision regulators on reagent and amidite bottles. These regulators are designed with a controlled, intentional leak to maintain accurate and stable pressure control.
Because of this design:
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A small amount of argon consumption while the system is idle is expected behavior
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This does not indicate a system leak or malfunction
When the manual valve is configured to use the Main pathway (Port #4):
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Argon is routed through Solenoid #2
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This solenoid is labeled “Main” in the software
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Solenoid #2 is automatically opened at the start of synthesis and closed at the end of synthesis
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This prevents argon from flowing to the bottle pathways when the system is idle
This software-controlled behavior is what enables argon savings after a synthesis run is complete.
Valve Positions Explained
The manual valve has three selectable positions, indicated by the arrow on the top of the valve:
1. Bypass (Port #2) – Default
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Automatically supplies argon to the bottle pathways
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No software interaction required
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Recommended for normal operation
2. Main (Port #4)
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Requires Solenoid #2 to be opened by the software
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Argon flows only during active synthesis
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Helps reduce argon usage when runs are complete
3. N (Neutral / Off)
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No argon flow through either pathway
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Not recommended for routine use
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Intended for service or troubleshooting scenarios only
Important Notes
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Continuous argon pressurization helps offset the controlled leak inherent to the precision regulators and reduces the risk of ambient air or moisture entering the bottle pathways
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Customers are not generally advised to adjust the manual valve unless directed by Sierra Bio service personnel
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Improper valve selection may result in no argon flow or unintended system behavior