Shearwater Research HP Wireless Transmitter - Grey

In Stock
This wireless transmitter screws in to the high-pressure (HP) port of a first stage regulator and can communicate with the dive computer to allow them to display the cylinder gas pressure without the use of the typical HP hose.

The two different case colors indicate different timing of the data transmissions. In single transmitter applications we recommend the gray color. In two transmitter applications we recommend using the yellow as the second transmitter to minimize interference with each other.

Shearwater Research HP Wireless Transmitter - Grey

SR HP Wireless Transmitter - Grey
SR HP Wireless Transmitter - Grey
  • Compatible with Shearwater Perdix-AI computer
  • Wireless transmission of tank pressure to your computer
  • Rated for depth up to {500 ft | 150 m}
  • Includes user replaceable CR2 photo battery
  • Also compatible with Hollis, Oceanic, Aeris computers

This tank pressure wireless transmitter (OEM by Pelagic Pressure Systems = FCC ID MH8A), is compatible only with those specific models of Shearwater Research, Hollis, Oceanic, and Aeris brand dive computers that support hoseless air integration. This includes the Shearwater Perdix-AI, Teric and NERD 2 model dive computers currently sold by Dive Gear Express, but does NOT include the Shearwater Peregrine or Perdix without the AI designation. The transmitter is rated for depth up to { 500 ft | 150 m }, and has a user replaceable, widely available, CR2 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) . The transmitter is available in two different case colors that indicate slightly different timing of the data transmissions although both colors use the same 38kHz radio frequency. In single transmitter applications we recommend the charcoal grey color. In two transmitter applications such as sidemount or CCR, Shearwater recommends using the yellow color as the second transmitter to minimize interference with each other. (Our transmitters are of recent manufacture and our yellow stock is NOT subject to the 2018 recall.) Using two of the same color transmitter may cause interference between the two transmitters that results in loss of communications about tank pressure.

Shearwater 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. If you want a well padded case suitable for boat use and with room for storage of the dive computer and transmitter together, consider using the optional DGX Padded Storage Bag.

The transmitter screws in to a high-pressure (HP) port of the first stage regulator mounted on the tank to be monitored. An antenna inside the dive computer receives the signals when it is positioned within { 72 in (6 ft) |1.8 m } 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 { 3 ft | 0.9 m } 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 { 3 ft | 0.9 m } 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, Dive Gear Express recommends following the best practice of also including a standard analog 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 6-inch HP hose pigtail (do not forget the required Air Spool) in place of the standoff.

NOTE: The transmitter has a user replaceable, non-rechargeable and widely available CR2 photo battery. The High Pressure O-ring located at the base of the transmitter is Size AS568-012, Viton™ material while the battery cap O-ring used is Size AS568-016, Nitrile (Buna-N) A70. Under normal circumstances neither o-ring requires routine replacement.

Just to clarify any confusion: The tank pressure wireless transmitter (OEM by Pelagic Pressure Systems) described, sold on this page and in bundles with the Perdix AI and NERD 2 dive computers is not related to, and is not affected by, the 2018 Suunto Wireless Tank Pressure Transmitter and Suunto Tank POD recall.

More Information
Brand Shearwater Research
SKU SRI-13004
Weight 0.450000

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 and may optionally require the cylinder rated service pressure be entered. Computers that calculate GTR based on observed SAC rate history 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, Dive Gear Express 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.