Inside the HYDPRO D01 Dry Suit Valve System

May 28, 2026

Inside the HYDPRO D01 Dry Suit Valve System

HYDPRO is based in Sori, Genoa. Underwater air management is the entire operation. Inflators, OPVs, hoses, connectors, dry suit valves. We've been carrying their hoses since we first wrote about why their construction stands out, and the D01 dry suit valve system applies the same discipline to the part of your kit that controls suit volume on every dive.

The patented tech, in plain terms

Two pieces of HYDPRO engineering define the D01 series.

HYDPRO D01 Rugged Dry Suit Exhaust Valve 3D

The first is the Pentagon system on the D01 Rugged exhaust valve. HYDPRO redesigned the geometry of the sealing membrane so its surface area is considerably wider than conventional designs. That gives the airflow more room to move. Per HYDPRO, the result is up to four times the exhaust capacity of competing valves. The same wider membrane self-seals as soon as residual pressure reaches zero, which keeps water from tracking in past the membrane when you hold the manual dump open a beat longer than you needed to.

HYDPRO D01 Stealth Dry Suit Inflation Valve 3D

The second is the piston loading system on the D01 Stealth inlet valve. The piston gives a wide inflation flow with gradual activation, so you can trickle gas in or fill fast without a step change in feel. The button is sized big enough to find and press with dry gloves on, and shaped to resist accidental activation from a hose pressing against it. The whole valve sits on a low-profile body that does not catch lines or accessories. A 359 degree rotation mechanism lets you orient the inflator connection for the hose routing that fits your rig.

Adjustable dump range

The D01 Rugged adjusts from 40 mbar of overpressure, the highest value allowed by regulation, down to fully open at 0 mbar. The wide range matters in technical diving where you might want to run minimum suit volume in low-clearance environments like caves or wrecks, and still have the option to dial it back up for travel or training dives.

Easy installation, easier service

For installation, the D01 series uses HYDPRO's S-Fit (34 mm) or L-Fit (38 mm) suit-port interface. The L-Fit is the same size as Apeks dry suit valves. A qualified drysuit technician fits the valve, with HYDPRO's D01 Tightening Key Set used to torque valve components to specification during installation and reassembly. Confirm your suit's port size before ordering.

For service, HYDPRO's design choice is that a serviceable valve stays safer over its life than a sealed valve that gets discarded when something wears out. The D01 Rugged uses a bayonet-mount design that lets a technician open the valve for cleaning and service without specialized disassembly. The D01 Unlock Tool releases the bayonet mount. The Substitution Kit D01 carries the wear parts, the seals and other consumables produced to HYDPRO's original-component specification, for a normal service.

Service is for trained technicians. These are life-support parts. But the option to service rather than replace is built into how the D01 series is designed.

Testing and certification

HYDPRO runs 181 laboratory tests on the D01 series, covering mechanical function, physical properties, and resistance to environmental conditions. Every valve is built to specifications validated by that test program. Per HYDPRO, the D01 series is certified to UNI EN 14225-2:2005, the European standard for dry suits.