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How does it work

The Mares Horizon is designed with one clear purpose: simplicity! It is easy to setup, transport, dive, and maintain, since every component of the unit is accessible by the user.

The unit’s internal components are easily accessed by removing the scrubbers that are located under the main outer cover. To keep everything small and light, the gas supply for the unit comes from one or two off-board cylinders, which gives the diver an experience similar to sidemount diving.

Mares Horizon is Variable Flow SCR:

The Mares Horizon is an active SCR with variable flow rates to maintain the desired fraction of oxygen in the breathing loop. The diver can decides what nitrox he wish to breathe on that particular  dive and set it in the computer.

To achieve a constant loop FO2, the SCR unit must constantly change the flow rate from 5 to 30 l/min, depending on the metabolic rate of the diver.

The Mares Horizon maintains a minimum flow rate of 5 l/min via the orifice at all times. During a dive, the fraction of oxygen in the loop is constantly measured. When the fraction drops below the set point, an electronically controlled valve or 'Electronic Addition Valve' (EAV) opens. This valve injects fresh nitrox into the breathing loop until the fraction increases to reach the set point.

The Mares Horizon is designed to allow for diving within the no-decompression limits or for decompression dives up to a maximum depth of 40 meters. To accelerate decompression two different gas mixes can be used; bottom gas and decompression gas. The bottom gas is used during the descent and bottom phase of the dive and the decompression gas is used for the decompression phase of the dive. Both bottom and decompression gases must meet the following criteria:

  • Minimum Oxygen Content: 30%
  • Maximum Oxygen Content: 100%
Breathing loop

The Dive Controller (DC)

The Mares Horizon Dive Controller (DC) is a high end, reliable dive computer that also plays an important role in configuring and executing dives with a variable flow SCR. It allows the user to enter breathing gas data as well as defining oxygen fraction setpoints to maintain during the dive.

Alarms and warnings

A warning is issued if any dive parameter is outside of its expected operating range. These warnings are displayed in situations where the diver’s life is not in danger

An alarm is displayed if a life-threatening situation should occur. This is a serious and potentially dangerous situation and the diver should take immediate action when an alarm occurs.

The BOV (bail-out valve)

In case, there’s any problem with the Mares Horizon, the diver can switch to breathe from the BOV. The bail-out valve, or BOV, is a device that allows an SCR diver to close their breathing loop while automatically switching to a small but high performing built-in second stage regulator that allows the diver to breathe in “open-circuit”, eliminating the need to remove the breathing loop from the mouth if the unit malfunctions. The BOV uses the same gas that supplies the rest of the unit.

Scrubber absorbing CO2

The only job of the scrubber material is to remove carbon dioxide from your exhaled breathing gas. The Mares Horizon has a unique dual-scrubber system that uses two scrubber canisters mounted in sequence to allow gas to flow from the upper scrubber to the lower.

For more information concerning particular procedures or components of the Mares Horizon, please visit out “Download” section.