Shearwater Research Inc.
Revision 1.1.0
60
Shearwater Petrel
Tissues Cleared
Some conditions will cause the decompression inert gas tissue loadings to be cleared�
When cleared, the tissues are set to being saturated with breathing air at the current
barometric pressure�
The Petrel does not lock-out when the tissues are cleared� If the tissues are cleared, then the
diver must take appropriate cautions when planning repetitive dives. The Petrel clearly notifies
when tissues are cleared, so that the diver has the proper information to make responsible
decisions�
For example, after changing the battery, you will see one of these two screens:
Conditions that cause the tissues to be cleared are:
Firmware Updates:
A firmware update will clear the tissues. Therefore, updating the firmware
in the middle of a dive trip is not a good idea�
User Request:
You can clear the tissues manually in the System Setup
System Setup
menu� Use the Reset To Defaults option� This will then prompt if you want to reset the
settings only, the tissues only, or both�
Slow Battery Change:
Quick battery changes do not normally cause the tissues to be cleared�
A super capacitor stores energy to keep the clock running for at least 15 minutes during a
battery change� If battery removed for longer than 15 minutes, then the tissues will be cleared�
Corruption:
A 32-bit cyclic redundancy check (CRC) is used to verify the integrity of the
tissues each time the Petrel is turned on� If corrupted, the tissues will be cleared� The most
likely cause of corruption is removing the battery with the Petrel turned on� Therefore,
turning the Petrel off before changing the battery is the best practice�
Changing To/From Gauge Mode:
In gauge mode the Petrel does not know what gas you are
breathing and cannot track tissue loading� Therefore, when changing to or from gauge mode,
the tissues are cleared�
Summary of Contents for Petrel EXT
Page 1: ...Standalone EXT Models...