Modification of the new sensor tray to avoid small deformations of the counter lung.

Lately we have been notified by some customers that they discover small deformations, indents, on the surface of the inhale counter lung.

It took us a little time to understand what is happening, but it is clear now:

At the bottom side of the new sensor tray, there are 2 small chambers where you enter the bolts that hold the O2 board or the carry handle

This chamber is on one side closed off by the bolts, and on the other side the counter lung if it is touching the sensor tray.

In the unlikely event that the counter lung is so perfectly touching the tray, and the ‘chamber’ is really ‘sealed off’ by the counter lung, so that no gas can flow from the counter lung into that chamber, a ‘vacuum’ effect will occur when you descend: as no gas can flow into the 2 chambers, and the pressure in the counter lung or the water around it increases, the counterlung is ‘pressed’ into the 2 chambers due to the overpressure. And so these small deformations occur.

We have not noted any lung perforations due to this effect, nor real damage to the lungs for further use, but it does not look nice and we want to avoid this in the future.

There is an easy fix to avoid this ‘vacuum’ effect: making a small hole from the ‘chamber’ to the area where the sensors are, so that there is never any pressure difference.

Using a 1.5 or 2.0mm drill, make a small hole trough the side of the chamber to the other side of the sensor tray, where the sensors are located. When you do this for the 2 chambers, there will always be pressure equalization, so the lung can not be ‘vacuumed’ anymore.

There is no need to completely disassemble the cables or the sensors: if you drill from the chamber to the outside of the sensor tray, there is no risk to touch any cables.

All sensor trays or units that were shipped on June 8th 2012 or later already have this fix. All previously shipped sensor trays still need this modification.

If you are unsure about this modification please don’t hesitate to contact us