The Shearwater Research Black HP Wireless Air Integrated (AI) Transmitter screws in to the high pressure (HP) port of a first stage regulator and can communicate with the air integrated dive computer to allow them to display the cylinder gas pressure without the use of the typical HP hose.
When using more than one transmitter, use one black and one yellow for best reliability. The Black version is recommended as the first transmitter. If adding a second transmitter, e.g. for a sidemount setup, we recommend using the Yellow version as the second transmitter.
This Shearwater Research tank pressure wireless transmitter (OEM by Pelagic Pressure Systems), is compatible only with those specific models of Shearwater Research, Hollis, Oceanic, and Aeris brand dive computers that support hoseless air integration. This includes both the Shearwater Perdix AI and NERD 2 models, plus the Hollis DG03 model.
The transmitter is rated for depth up to 150 metres (500 feet), and has a user replaceable, widely available, 3V CR2 Lithium photo battery. Each transmitter has its own unique ID and multiple transmitters can be linked to compatible dive computers (up to two for the Shearwater).
Shearwater Research supplies the transmitter with a small zippered hard case. The Shearwater case included with the transmitter is a very snug fit, suitable for dry storage, but not suitable for boat use or damp storage.
The transmitter screws in to a high pressure (HP) port of the first stage regulator mounted on the tank to be monitored. The Scuba Doctor recommends that the Shearwater Research AI Transmitter be mounted on the end of a 15 cm (6 in) high pressure hose, rather than screwed in directly to a 1st stage regulator high pressure port.
An antenna inside the dive computer receives the signals when it is positioned within 1.8 m (6 ft) of the transmitter and within a zone parallel or at a 45 degree angle to the transmitter. Best reception is achieved when the dive computer and transmitter are within 0.9 m (3 ft) of each other. During a dive you may at times move the dive computer so that is out of the signal pattern of the transmitter, resulting in a temporary interruption of the link. The link may also be interrupted if the dive computer is within 0.9 m (3 ft) of a running DPV, or after a strobe light flashes. The link will be restored within 4 seconds after the dive computer is reoriented, moved back into range, or the interference clears. For technical diving, The Scuba Doctors recommends following the best practice of also including a standard analogue SPG on the regulator as a backup.
In rare cases, the body of some first stage regulator designs will have hose ports oriented such there is not room to accept a wireless tank pressure transmitter without interfering with hose routing. The solution is to use a standoff adapter, or some divers prefer to use a short 15 cm (6 inch) HP hose pigtail (do not forget the required Air Spool) in place of the standoff.
Shearwater Research HP Wireless AI Transmitter Features
- Compatible with Shearwater Perdix AI dive computer
- Wireless transmission of tank pressure to your dive computer
- Rated for depth up to 150 m (500 ft)
- Includes user replaceable 3V CR2 Lithium photo battery
- Nitrox compatible rated up to 40% O2
- Also compatible with Hollis, Oceanic, Aeris computers
- Two year warranty against manufacturing defects
Shearwater Research HP Wireless Transmitter Specifications
- Battery Type (user replaceable): 3V CR2 Lithium
- Battery Life: 300 Hours
- Depth Rating: 152 m (500 ft)
- Wireless Mode: Low Frequency RF 38kHz
About Gas Time Remaining (GTR) Calculations
Some dive computers have the ability to monitor a sensor that allows them to provide a digital display of the gas pressure in the dive cylinder. This feature is often referred to as 'air integration' (AI) but since nearly all modern dive computers are capable of handing a variety of breathing gases the term air is a misnomer. A few of the AI computers go a step further and use the tank pressure to calculate an estimate of the breathing gas time remaining (GTR). There are a variety of different methods and formulas for GTR calculations but they all share limitations such that, for specific divers and specific dives, the GTR displayed by your computer can be wildly inaccurate.
Just to be clear, the accuracy of the GTR is not a limitation of the computer or the transmitter but because there are simply too many unknowns to make the GTR anything other than a gross approximation. Beyond the obvious factors such as environment, depth variations in a multi-level dive profile, ascent rates, and stop times; the divers gas consumption rate will vary greatly depending on changes in equipment configuration and exertion. For this reason, GTR estimates are meaningless on most technical dives, and even some deeper sport dives, particularly if hunting.
Another factor that can affect the GTR depends on the algorithm used for making the estimate. Some methods require the diver to know and enter an RMV consumption rate along with the volume of gas available (i.e. 'tank size'). Other methods use an observed SAC rate to develop a prediction based on consumption history. Computers that calculate GTR based on observed SAC rate history are user friendly and less prone to configuration error but are particularly problematic when the diver uses different capacity cylinders on different dives.
While the GTR can be useful in warning inexperienced sport divers when gas consumption is abnormally high, The Scuba Doctor does not recommend relying upon dive computer GTR estimates to control or extend the dive time. Never allow the computer GTR estimate to become part of your dive plan, always closely monitor your actual tank pressure.
Please Note: We try to keep Shearwater Research products in stock. As we source them direct from Shearwater Research in Canada, it can take 7 to 14 days for more stock to arrive if we run out.
This product has a limited warranty of two (2) years.
Note: This item cannot be delivered outside of Australia.