Design, Engineering, Prototyping.

The Nitrox Controller is used by Dive Shops to automate and make safer the process of blending Nitrox.  It can be used with either of the two commonly used technologies, the semi permeable membrane systems that vent excess nitrogen, or the Nitrox Stik Continuous Gas Blender that adds oxygen from a tank.

The Need:

My buddy, Brian, owns a dive shop and a dive boat (www.DiveOahu.com).  His shop fills SCUBA tanks and he recently purchased a Nitrox Stik Continuous Gas Blender system to make Oxygen Enriched Air (Nitrox).  His system uses large O₂ tanks and a patented blending “Stik” to homogeneously mix air and pure oxygen at the inlet of a high-pressure air compressor.  The gas that comes out of the compressor is air, enriched up to 40% oxygen.

While the system works great, it needs to be continuously monitored, and the flow rate of oxygen must be constantly adjusted to maintain the desired mix.  Safe blending practices dictate that a well-trained person be continuously present to safely operate any gas blending system, including the Nitrox Stik Continuous Gas Blender.

However....  We've all done our share of staring at meters and gages that don't move;  it's extremely boring.  Unless we are disciplined enough to maintain our vigil, we probably won't do it properly.  More often than not, we end up doing other things "while" we are watching.  Unfortunately, this leads to complacency in our watching practices, and we become unsafe operators.  The Nitrox Controller helps mitigate this very real concern.

Brian was becoming complacent, and invariably, he would be attending to some other urgent matter at the shop when the compressor shut down.  He would run to turn off the O₂ supply as soon as he heard the compressor shut down, but there was always a period of time when pure oxygen was being vented into the compressor intake area.  If the compressor was restarted without ensuring that the oxygen had dissipated, the compressor could take in a high concentration of oxygen, potentially damaging the compressor internals.

The Solution:

Brian wanted something that would take the hassle out of blending Nitrox so he would be free to do other things in the Shop.  He was also concerned about the safety of an  unattended system venting pure oxygen into the compressor intake area.  We put together a Nitrox Controller system with a number of features that addressed all of his needs:

• Maintains Desired O₂ Mix within Close Tolerance (+/- 0.1%).
• Medical Grade Oxygen Sensor.
• Easy to Calibrate.
• Electronically Controlled Proportional Valve to Control the Addition of Oxygen.
• Auto Shutdown Feature Closes the Oxygen Control Valve when the Compressor Turns Off.
• Buzzer to Alert Operator if Oxygen Concentration is not within 2% of Set Point Value.
• Nitrox Controller Automatically Shuts Oxygen Control Valve in the event of a High Oxygen Condition (40%) or System Malfunction. 
• Wire Lengths Long Enough to Allow Mounting the Controller Visibly in the Shop while the Nitrox Stick, Compressor and Oxygen Cylinders are in a Separate Location.

Watch the Nitrox Controller Video.  Big File (45 Meg), down load takes a while, please be patient.

Click here to see our Suggested Nitrox System Configuration.

The Nitrox Controller is available with electrical connections on the back of the enclosure for a cleaner installation appearance.

Nitrox Controller Installation and Operating Instructions are provided below in PDF format for the Nitrox Stik Continuous Gas Blender installation.

View the Nitrox Controller Operating Instructions Placard.

View the Nitrox Controller Installation Instructions:   Quick Version,  Comprehensive Version.

The University of Hawaii at Hilo just sent us a great letter commending us on our Nitrox Controller.  UH Hilo Letter to RDD

How to determine the actual flow rate of your compressor.

Customer submitted Nitrox Stik and Nitrox Controller Pictures.

The schematic below illustrates how the Nitrox Controller is incorporated into the Nitrox Stik Continuous Gas Blender technology to make Enriched Air for SCUBA.

The patented Nitrox Mixing Stik Continuous Gas Blender and additional information about Enriched Air Nitrox (EANx) for SCUBA is available from Enviro Dive Services.

The schematic below illustrates how the Nitrox Controller is incorporated into the Nitrogen Separating Membrane technology to make De-Nitrogenated Air (DNAx) for SCUBA.  In this configuration, the Auto Shutdown feature is not used.  A temperature compensation circuit is used to counter act the effect of heating the oxygen sensor.

The schematic below illustrates how the Nitrox Controller is incorporated into a low pressure version of the Nitrox Stik Continuous Gas Blender technology to make Enriched Air for surface supplied diving.

Nitrox Controller installation and set-up is simple with common tools.

Nitrox Controllers for use with the Nitrox Stik Continuous Gas Blender are available for purchase from Rubber Duckie Designs for $3700 (for up to 14 CFM compressors) and $4500 (for 15  CFM and larger compressors) and come complete with all necessary parts.

In order to purchase the correct sized Nitrox Controller for your Nitrox Stik Continuous Gas Blender, you should know the actual flow rate of your compressor.  How to determine the actual flow rate of your compressor.

Nitrox Controllers for use with Nitrox Membrane Systems are available for purchase from Rubber Duckie Designs for $4700 for systems capable of generating 40% Nitrox at 20 CFM .  You may need to obtain some brass fittings to connect the Solenoid Operated Control Valve to your specific application.

Call Derek at (808) 392-8252 or email at Derek@RubberDuckieDesigns.com for more information.

Nitrox Controller Support Download Page : contains the materials that initially came with your Nitrox Controller.

The Nitrox Safety Valve is an inexpensive alternative to the Nitrox Controller.

Last modified: 12/23/08