Closed Circuit Draeger FGGIII

This is the new scrubber. The housing was machined from C100 nylon, which is a marine grade nylon with a low absorption coefficient. The internal fittings are marine bronze. There are o-ring seals on the top and bottom lids, and where the fittings protrude through the lid. The two bronze fittings connect to the breathing bags via o-ring seals and screw connectors, the centre one to the exhalation bag, and the side one to the inhalation bag. The blue hose is the cable hose to the electronics housing. The two quick disconnects are for O2 connectors, the nearer one is attached to the solenoid which is mounted directly below, and the far one vents straight into the sensor plenum in the scrubber top.

The scrubber holds 3.2 litres of sorb.

The scrubber with the bottom cap removed. This is where you fill it with sorb. The exhaled gas comes down through the tube in the centre, then passes through the stainless steel mesh and up through the sorb into the sensor plenum. The stainless springs keep pressure on the scrubber bed in case of settling.

The internals of the scrubber inverted. The long tube is where the exhaled gas travels from the exhalation bag into the bottom of the scrubber. After passing through the scrubber bed, the gas goes through the stainless mesh shown and into the sensor plenum between the bed and the top lid. You can also see the bronze fitting which passes gas from the sensor plenum into the inhalation bag. Just visible is the O2 solenoid. The discolouration on the bronze tube is from leaving sorb in the scrubber for two weeks after use. I think I will have the bronze pieces nickel plated to prevent this. Or maybe just empty the unit after use!!

Top lid of scrubber (inverted) showing the sensor plenum with the upper stainless mesh removed. As you can see, there are three Teledyne R22 oxygen sensors, and a Snaptite Wattmiser solenoid. Note the o-ring groove in the recess where the scrubber body mates with the lid. Also visible, just to the left of the solenoid, is the manual oxygen addition orifice.