Deep Dive into Reading

Poseidon Head made by Underwater Technologies

The Configuration of the head has the possibility to use up to three oxygen cells, two independent power supply sources (battery type: LiPo 18650) and a low-power solenoid Clippard.

Fig. A. AV1- Underwater Technologies Poseidon Head.

A discussion about solenoids and Kiss valve:

A Kiss valve needs at least between 12-13 bar of pressure to works correctly, Clippart works with a very low intermediate pressure, not good for a mCCR with a Kiss valve. If the divers wants to add a Kiss valve, it’s good idea to use Jaksa solenoids, as they can work up to 17 bar of pressure.

Clippard solenoid

AV1 controller on the Poseidon Head comes with a Clippard solenoid. It works good up to 9 bar, but the recommendation is to set the regulator intermediate pressure between 7.5* and 8 bar. But is better to set it at 7.5 bar, which is the lowest setting.

7.5 bar = 109 psi (pounds/square inch), 750 kPa (kilopascal)

1 bar = 14.5 psi ,100 Kpa

Conversion units

For Diluent, Make sure the 1st stage is set to an intermediate pressure of 8,5 bar / 123,25 psi

You can modify the head to add another port for DIL injections directly to the head, nonetheless the head comes with three ports: two of them are for cables, controller and head-up display (HUD), the last one is for the Oxygen port. On the figure A, you may identify the added port colored in blue which serves as DIL injection port.

MAV Fig. B

 The MKVI mouthpiece also combines in the same housing a pressure balanced “Automatic Diluent Addition Valve” (ADV) that compensates for breathing volume in closed-circuit mode. So for you to have an additional way to inject DIL into the system. You may have different alternative besaid this one; for example, a manual injection valve port on your conterloung or an inlet adapter on the head breathing manifold (exhalation) with an injection valve or a double MAV block. At the end, you may have many options.

How the controller works

AV1eCCR controller manages the solenoid and supports preset setpoint based on information received from oxygen cells.

Oxygen is supplied by the solenoid in cycles: every 5 seconds – fixed pause, and 0.2-20 seconds – Oxygen supply. Time of Oxygen supply is calculated by the controller and depends on several factors:

  • Difference between the setpoint and O2 level change in the loop (proportional share);
  • Oxygen level change speed in the loop (differential share);
  • Weighted error time (integral share).

The controller works with two independent power sources B1 and B2. By default B1 is the main power source. If during operation B1 discharged to less than 20% of nominal charge, then the controller switches to using B2 battery. If then B2 battery also discharges down to 20% and less, then power supply will be made from both batteries at the same time (connected in parallel).

The HUD-s has two independent function and its connected to the same set of batteries. First works in conjunction with the controller and second it’s capable of reads the oxygen cells independently from the controller. So it has a different set of lights for each function.

This is so, because in the case of a controller malfunction, you can finished the dive on the loop following the hud display.

The hud has a set of lights for the controller: red and green and it will presents you with the following information:

  • Green Light:
    • If everything is in order, but PO2 differs from the preset Setpoint by more than 0.2, but less than 0.4, then green indicator is slowly flashing (PO2≠ Set point <> 0.2 < 0.4) ;
    • If everything is in order, but PO2 differs from the preset Setpoint by more than 0.4, then green indicator is quickly flashing  (PO2≠ Set point <> 0.2 > 0.4)
  • Red light and the alarm appears on the controller screen:
    •  Ascending speed is high (faster than 10 meters/min.);
    • Decompression ceiling depth violated;
    • Any of the oxygen cell is out of order;
    • РО2 is more than 1.6;
    • РО2 is less than 0.4;
    • Low battery charging level;

In addition, the hud functions independently, it will inform you the values of the PO2 sensors throughout a set of lights. For that reason you should calibrates it as well and, you should enter the correct ambient pressure during the calibration process because the it does not has a pressure sensor. The hud vibrate as well.

Download the manual here.

Fig. C The Av1 Head

The Outer shell – Cartridge housing

If you look into the housing, you’ll identify a small o-ring where the original head seats, this o-ring must be plugged with a special tool that comes with your AV1 kit. Thi is done in order to the injected gas mix well in the head.

The diagram below represent the gas flow into the housing:

Gas Flow
Diagram A

Also pictured is the right T-connection. The MKVI use two T-connections which divert water and trap it into the counterlongs. Because of the direction of breathing flow and the one-way check valves in the mouthpiece, almost all water that leaks into the system collects in the right counterlung, where it can be dumped via the check-valve port at the bottom of the counterlung, pictured in the diagram.

Important considerations using the controller

  • You have the possibility to fix which cell the controller will manage (cell: 1,2,3) , also you could do this during the diving.
  • The controller can manage various types of oxygen cells like R22, R17 or similar type.
  • You can calibrate form air up to pure oxygen.
  • The controller will switch automatically the set points, from low to high, but decompression set point should be do manually. Although you can perform all the switching manually.
AV1 Controller

PO2 Calculations

With 3 (three) Oxygen cells connected, the controller ignores the value displayed by one cell that shows value much more different from the rest, this cell is considered as a failed one. The cell value will be display in yellow color and the rest in Green. A cell warning will be on screen if any cell differ from the rest by more than 0.4 points.

You can use two oxygen cells. The calculate PO2 is an averaged from these cells. Same warning rule is performed.
Likewise you can use one oxygen cell , no accuracy control of cell operation is carried out.

During dive you have the option to perform check cells, the information displayed on screen will have PO2, mV cells, pressure, gas used, etc.

Adding a scrubber cartridge for refilling

The last piece of equipment you may add is a scrubber cartridge for refilling. The advantage of this system is long term price, it’s not necessary but convenience.

Fig. D. Brand: Tecme. Max filling with the small 797 is 2,3kg.

Putting all together

You have already all the components to make a new eCCR without restriction from the Mark VI. You have a lot of combinations and possibilities to make it your own.

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