CASE M14 - Air System Drying After Cleaning or Hydro-test, R. Johnston
Inadequate or time consuming drying of chamber air piping systems.
Moisture in system which may lead to corrosion.
Collection of Facts: Various cleaning procedures have been developed which
rely on forcing dry, warm air to dry the piping system. Not only is this very
time consuming, but water may not be thoroughly removed from recesses or "dead
ends" of the system.
Solution: After purging system with air for approximately 4 hours, pull a
vacuum on the system for at least 4 hours. A vacuum of 10 inches of water
(.73 inches Hg) should be sufficient to boil off any water left in the system.
CASE M15 - Location of Intake for Air Supply, R. Johnston
Improper location of compressor air intake for chamber air supply
Carbon monoxide contamination of supply air system.
Collection of Facts: The compressor air intake and filter should ideally be
located above the roof outside of the building. In some instances, the intake
has been located at ground level in proximity to vehicle exhaust.
Solution: Extend compressor air intake and filter through the roof using a
length of PVC pipe appropriately sized. Care should be taken to avoid placing
the intake near diesel exhaust stacks, toilet vents, etc.
CASE M16 - Pressurization of Chamber Fire Extinguisher, R. Johnston
Inadequate pressurization of chamber fire extinguishers.
Symptom: Ineffectual spray pattern in the event that extinguisher is operated
Collection of Facts: While most chambers are now equipped with
gas-pressurized water extinguishers, inspections have indicated that some
extinguishers are charged to only 100 psig. Research has shown that a charge
of 200 psig is necessary to provide adequate flow when the chamber is at depth.
Solution: Regularly inspect chamber fire extinguisher to ensure that it is
charged to 200 psig.