NEWS | June 11, 2020

ALSE: Got Underwater Breathing Device Issues?


This article initially appeared in PS 794 (Jan 19), p. 24.

Units with the Aqua Lung survival egress air breathing system, including SEA-MK and SEA/LV2 versions, listen up!

During rapid purging situations, the HP seat disc material of the first stage ON/OFF valve may poke out from the seat retainer, cutting off the air supply. The seat doesn’t fully separate from the retainer, but only sticks out a tiny bit. It can usually be reset by completely closing the ON/OFF valve and then reopening it.

This problem is only known to occur in high-use training facilities where Christo-Lube was applied and may have accumulated over time. Lubricating the seat and disc retainer assembly or the internal threads of the first stage body can keep air pressure on both sides of the valve seat from equalizing.
 
Have breathing device problem? Have a trained technician inspect seat and disc retainer assembly inside
Have breathing device problem? Have a trained technician
inspect seat and disc retainer assembly inside

 
Any corrective action should be done only by an authorized technician trained to repair and maintain the SEA. The work must be done exactly as the commercial TM says.
 
An authorized technician must inspect seat and disc retainer assembly for equal pressure on both sides​
An authorized technician must inspect seat and disc
retainer assembly for equal pressure on both sides​
 
Function Check

Using a fully charged cylinder, open the ON/OFF valve and follow these steps:
 
  1. Start an extreme rapid purge by pressing the purge button fully on the second stage of the survival egress air (SEA). Wait until the cylinder is completely depleted. Note: Monitor the high pressure indicator during the function check. A rapid drop of supply pressure indicates a malfunction.
     
  2. If air flow stops quickly before cylinder depletion, the system fails the function check. Remove it from service and proceed to Step 4. A gradual stop of the air flow (under 500 psi indicated) is normal as the cylinder pressure depletes.
     
  3. If air flows without interruption while depleting the cylinder, recharge the system. Repeat Step 1, keeping the valve in the ON position. Again, a gradual stop of the air flow (under 500 psi indicated) is normal. If the unit passes this second test, return it to service. 
     
  4. For systems that fail the function check, replace the seat and disc assembly (PN 108322) and O-ring, (PN 520015) with new parts from Aqua Lung. Follow the modified instructions in the SEA TM listed on Page 26. Note: After removing the old parts, clean the threads of the body with a lint-free swab or cloth. Do not reapply lubricant to the seat and disc retainer. That can trap debris in the threads.
     
  5. With the ON/OFF valve partial rebuild complete, fully charge the system and repeat a single test (Step 3.) If the unit passes this final test, return it to service.

The modified procedure for Rev 1/16 of the Survival Egress Air technical manual, needs the following change:

Under Reassembly of Handwheel in Para 17 on Page 13, delete “Lubricate the threads of a new seat disc & retainer (29).” 

Replace it with “Do not lubricate the threads of a new seat disc & retainer (29).” 

This change will be added to the next TM update.

Got Questions? Contact David Bath by email: