[R-390] Cosmos Dis-assembly

[rbethman]

Tisha,

No, you are NOT lost!

Someone simply posted a description directly from a "reference".  
Thereby unintended but overkill in "honing" your very apt and correct post!

We didn't "need" to know the chemical "structure" and reactant means.

The bloody desiccant is a bright deep blue when first 
dried/manufactured.  It goes through a progression of of changes in 
color as it absorbs water vapor/humidity.  Eventually it is indeed very 
pink when it has done its job.

We had dozens of these packages about a quart in size that used to go 
into the Engine containers when we either shipped a re-manufactured gas 
turbine engine, or a new one to whom needed it.

We had these bags by the case.  Once the smaller box was opened, we had 
to bake the dozens needed to deal with the next engine.  We always had a 
BUNCH sitting in an oven purchased off the commercial market that any of 
us would have loved to take home!  I don't believe that it was shut off 
the whole time the shop ran.

BTW folks.  The nitrogen pressurization was done on the engines ALSO.  
The only time this was compromised, other than unbolting the top from 
the bottom of these containers, was *IF* the engine was transported by 
air.  Obviously, having the container blow a gasket and perhaps damaging 
the engine during ascent, it had a valve that allowed to leak a portion 
of the nitrogen to prevent it.

The same situation was encountered during descent.  The valve had to 
allow the increased air pressure to be equalized to prevent collapse of 
the container and damaging the engine.

The manufacturer's of PTOs were dealing with the same issues.  If you 
simply use desiccant without removing *ALL* moisture from the air, 
you've compromised it when you close the can.  Therefore, *DRY* nitrogen 
is applied to the PTO "sealed can" when built or overhauled at depot.

We had upwards of a hundred outgoing containers, and fluctuating close 
to the same number of incoming containers.  We used to tear them down in 
a rotating frame.  Had to do an inspection,, and then determine whether 
it was going to be the whole enchilada tore apart, or if it went through 
a shorter line only doing repairs and the SAME complete checkout as the 
whole enchilada.  (This included, at that time, a full compressor 
stall.  Not for the faint hearted!  Have you ever seen a 15,000 HP jet 
engine shoot a flame out both the intake and exhaust about 15 foot long, 
visible in bright light?  It begins with a tiny runble, a very short 
silence, followed by an entire test chamber that suddenly has both ends 
fill with flame and a VERY loud BOOM!

They finally determined that this test was NOT necessary.  It destroyed 
too many of the engines that were perfectly good.

Sometimes Uncle Sam got carried away!

<This is based on years of work on gas turbines, especially the J-79s. ( 
GE LM-1500s ) >

Bob - N0DGN
Retired E-7

On 4/15/2010 7:36 PM, Tisha Hayes wrote:
> I am lost.
>
> On Thu, Apr 15, 2010 at 11:51 AM, Tisha Hayes<tisha.hayes at gmail.com>  wrote:
>
>    
>> Generally, the blue color of desiccant is a good thing. For color changing
>> desiccants they will turn pink in color when the moisture level gets above
>> 10% or so.
>>
>> Baking the desiccant in the oven at around 200 F is a good idea, no matter
>> what the color is. This does not take long, let your oven get up to 200 F,
>> put the desiccant capsules on a baking tray or pizza pan and turn the oven
>> off. The residual heat in the oven will dry out the capsule. Put the
>> desiccant capsules in a old pill bottle until you are ready to reassemble.
>>
>> Pay particular attention to the threaded rod inside of the PTO. Clean this
>> with a cotton swab to get rid of any contaminants.
>>
>> --
>> Ms. Tisha Hayes/ AA4HA