With new installations we would ordinarily start the pre-commissioning
tests with a strength pressure test, perhaps for 30 mins, followed by
a 24hr tightness. Then there is a 24hr vacuum finished off with a 30
minute vacuum rise test for moisture.
Is this similar to your procedures?
Assuming the piping system inadvertently took on say a pint of water
with out you knowing. What would you expect to see on the Torr gauge
after a 24 hr vacuum.
I have done a few calculations and have recently made a discovery
which I'd like to share but first I ask the above to set a benchmark
against which to discover what is common practice and what might
become new practice.
On Tue, 13 Jan 2009 14:34:42 -0800 (PST), "Marc O'Brien"
Five gallons of used vaccum pump oil and a micron gauge reading of
Marc I had a chiller barrel leak and it took me damn near a week to
de-hyrdrate the system after I replaced the barrel and it was only a
50 ton machine.
One of my favorite things to do is put a small amount of water in a
sealed glass jar and observe the process of moisture removal with an
apprentice. Its fun to watch the micron gauge to see at what level
things take place.
At first the water boils violently then it turns to ice then it
sublimes and disappears.
My next article in the UK industry magazine I write routinely for will
be on how I insist that the industry's traditional moisture checking
method be changed. I believe it is flawed. I don't want to give all
the details right now because I first want to be sure that no one else
known to me is aware of the flaw I have identified.
In your chiller case above the best process would have been a
combination of triple vac and deep vac. Triple vac does not remove
water but does remove vapour contaminants by compounding percentage
reductions - 4% is left in the system after the first vac and then 4%
of 4% after the second and finally 4% of 4% of 4% on the third vac and
so on. Only a deep vac with multiple vac oil changes can remove water.
The more heat the better and the better your cold trap the less often
you have to change the oil. But we cleaned a large system up pretty
quick finishing yesterday after 4 days of alternate deep vac and warm
nitrogen purging to about 30psi each time. The nitrogen was put into
the system through a length of copper pipe heated by hand with a blow
torch. The nitrogen was going in each time at about 40°C. Warm
nitrogen is an old trick of mine I chose to do on my own as an
apprentice years back.
My question everyone is really - at what point after a vacuum do you
check for moisture and how is it you know you have no moisture - what
instruments and what time frames do you use. This is for piping on new
How much water do you use? How long does it take to sublime away? I'm
assuming this is all done at room temperature and the glass jar is not
sat on a heat source warmer than the room.
I guessed the black was a little copper oxide from a few joints the
guys might have soldred without nitrogen purging.
I am just the methods consultant on this project. I have asked them to
install temporary replaceable drier cores starting off with a few
changes of Molecular Sieve and then to finish off with a few changes
of a Activated Alumina to remove the acids that would have been
generated by the oil/water reactions.
I've uploaded a video of the ice we removed from one of the suction
strainers on the system recently meant to be commissioned if it
weren't for the water.
We are a service providers for HVAC, ELECTRICAL, PLUMBING, FIRE-
We do designing and development for all the above services, not an
execution part at this time.
So we look for any OUTSOURCING jobs from any of the related clients
and the customers.
If you have any contacts or any links or if u share me the orders for
my concern, i think that it
is my pleasure to co-operate and satisfy the customers and the
So i think that it is suitable for my request and it is our duty to
serve for your concern. And sure that i am waiting for your positive
reply from your side. If you satisfy about my reply means shall i send
my company profile and same as from you side also.
And also we have our associate contractors and suppliers and dealers
Thanking you in anticipation,
How large of a system are we looking at? A pint of water in a system that
is two pints in size will no doubt have a different reaction to the
a system that's 50 million pints in volume. Moisture is moisture yes, but
you can't make a procedure that is all encompassing as ever job has it's own
However, if I were to suspect contamination were present I'd first try and
determine how it entered the system rather than treat the symptom. After
I'd remove the moisture, and then evacuate the system with a micron gauge
connected, breaking the vacume at various stages with a dry compressed gas,
such as nitrogen or perhaps with
a trace amount of refrigerent to help scavenge the moisture, until I
achieved a deep vacume that would hold. There's no time limit either, I've
had systems take a few weeks to remove
the water/moisture to a point where I was confident enough to walk away from
the job knowing that the system was perfectly free from contamination.
You're not telling us your operating pressures (normal) so I can't comment
on your pressure test. Again... a 30 pound test on a system that runs at 300
would be kind of useless don't you think? But I use a 1.5 times the normal
operating pressure for my tests, and then it's done for 24 hours. Any drop
is absolutely unacceptable.
A New York State Journeyman :)
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