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SI Tech THETIS Exhaust Valve — Combined Drysuit Dump Valve
€59.60 tax incl.
( 49,67 € tax excl. )
Availability:
In stock
Reference:
91741
The SI Tech THETIS is a combined automatic and manual exhaust valve designed for drysuits. It provides precise buoyancy control by regulating residual air venting during ascent, making it equally suited to recreational divers new to drysuit diving and experienced technical divers managing complex decompression profiles.
SI Tech THETIS Drysuit Exhaust Valve: Combined Purge System
When buoyancy control in a drysuit becomes critical — particularly during a rapid ascent or an accidental inversion — the quality of the exhaust valve determines whether the ascent stays controlled or turns unmanageable. The SI Tech THETIS is a combined exhaust valve: a single body integrating two operating modes — automatic venting via differential pressure and manual purge by direct pressure on the push button.
Design and Differential Mechanism
The THETIS operates on a diaphragm valve principle: a flexible seal opens as soon as the suit's internal pressure exceeds ambient pressure by an adjustable threshold, venting excess air without any input from the diver. This differential threshold — the opening pressure — is set by rotating the outer valve body, allowing sensitivity to be tuned to the dive profile and the diver's build. In manual mode, pressing the central button mechanically opens the seal for an immediate purge, regardless of the current differential pressure.
The valve body is machined from a corrosion-resistant material compatible with both salt water and fresh water environments. The O-ring seal between the valve and the suit is sized for standard fitting on the industry-common drysuit bore diameters. The compact profile minimises external protrusion, reducing snag risk in confined environments such as wrecks, caves, or dense underwater vegetation.
SI Tech is a Swedish manufacturer with several decades of specialisation in drysuit accessories — inflator valves, exhaust valves, wrist seals, and closure systems. The brand equips suits from numerous European manufacturers and is well established in technical diving, ice diving, and professional diving circles for the reliability of its components.
Applications
The THETIS exhaust valve covers a broad range of drysuit users:
- Recreational divers in cold water: automatic venting simplifies buoyancy management for divers new to drysuits by reducing the need for manual intervention during ascent.
- Technical (tek) divers: fine adjustment of the differential threshold allows the valve to be tuned to extended decompression profiles, where precise buoyancy control at each stop is essential.
- Ice diving and extreme cold water: the manual mechanism remains fully operable with thick gloves, thanks to the large-diameter central button that requires no fine motor control for emergency manual purging.
- Professional and scientific divers: the machined body's robustness and compatibility with work drysuits make it a common choice for extended operations in industrial or scientific environments.
Fitting and Compatibility
The THETIS fits the standard drysuit bore, typically located on the left arm or torso depending on the suit configuration. Installation is achieved by tightening the inner lock nut — no specialist tooling required beyond a spanner wrench or SI Tech's own fitting tool. The valve is compatible with membrane drysuits and compressed neoprene drysuits, provided the bore diameter meets SI Tech's standard specifications. When replacing an existing valve, verify bore diameter compatibility against SI Tech specifications before fitting.
For full guidance on drysuit equipment maintenance and use, refer to our non-PPE diving equipment guide on Proteushop.
Key Features
- Dual automatic/manual operation: a single body combines differential automatic venting and manual push-button purge, eliminating the need for two separate valves on the suit.
- Adjustable differential threshold: rotating the outer body sets the automatic opening pressure, enabling fine-tuning to the dive profile and diver preference.
- Large-format central button: operable with thick ice diving or cold-water gloves without requiring fine dexterity for emergency manual purging.
- Corrosion-resistant body: compatible with salt water and fresh water, built for long service life under intensive use by professional and technical divers.
- Universal standard fitting: compatible with the standard bore of membrane and compressed neoprene drysuits from major European manufacturers.
Official Documentation
91741
Specific References
- Manufacturer reference
- SITECH11330
The SI Tech THETIS is a combined automatic and manual exhaust valve designed for drysuits. It provides precise buoyancy control by regulating residual air venting during ascent, making it equally suited to recreational divers new to drysuit diving and experienced technical divers managing complex decompression profiles.
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