R -410a versus NH3

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Merlyn
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R -410a versus NH3

Postby Merlyn » Fri Mar 20, 2015 1:28 am

Bouyed up with my current success rating concerning my soon to have Stompers Medal my brain feels like the tension springs on the bob weights of my governor have let go and as the plus gas seeps in even further I am racing away and are being pushed way over my governed rpm and the thoughts of yesteryear struggle to the surface even more. Now any self respecting proper marine engineer should know the answer to this one. It is without doubt the most important information concerning NH3 that you could ever have in your life. Having said that no Q&A in seconds, firsts, Chiefs or extra Chiefs exam books contain this important knowledge. This is the hold that, ( and I know you guys navigating yourselves around and through all that ice are supporting Freon as I understand it was invented in your neck of the woods over there ) will never be broken. Although I am going for gold with important old time knowledge failure to provide the correct answer will indicate to me that there are a lot of engineers out there who have led a very sheltered life indeed and although they may have various tickets might not in the real world be PROPER marine engineers? So come on all you banana/lamb ship men, why do we say VIVA NH3??? :lol:
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: R -410a versus NH3

Postby JK » Fri Mar 20, 2015 2:20 am

The closest I came to 'Monia was when my old granddad broke open the coils on an ancient refrigerator and I was downwind. I was maybe 6, it's a wonder he didn't gas me. Well he did, it was a very unpleasant sensation.

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Merlyn
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Re: R -410a versus NH3

Postby Merlyn » Fri Mar 20, 2015 2:40 am

As you were only 6 you would not legally do what NH3 would cure you of?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: R -410a versus NH3

Postby Big Pete » Fri Mar 20, 2015 10:52 am

Ammonia was banned from Marine Refrigeration before I came to Sea: -
a) because it was extremely Toxic
b) It corroded Copper and Brass vey rapidly and there were too many accidents where the ship's Engineers had "repaired" pipework using the wrong materials and ended up killing people.
It has always been cheap and readily available as well as being more efficient than the modern zeotropic and azeotropic blends, much greener because you use less energy to drive the plant. Also, used in the Ammonia adsorbtion cycle it refrigerate without any moving parts, only an external heat source, although of course this can now be done using thermoelectric effect.
I have sailed with CO2 , Freon 11, 12, and 22 as well as the new blends but never Ammonia, so you will have to look for a real old timer to answer this one.
BP
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Merlyn
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Re: R -410a versus NH3

Postby Merlyn » Fri Mar 20, 2015 11:14 am

Well, that well and truly put me in my place. Good job I never lied about my age then, really would have been caught with my trousers down there, must be someone out there who knows the answer, J J? Someone must be able to stop me claiming yet another victory? I ran a large NH3 plant our firm had for 3 years when I finished my time, 7 days a week, 365 days a year, loved every minute of it. Only left when it closed after about 50 years of operating, ( no not with original kit) so come on somebody, what's the answer?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: R -410a versus NH3

Postby JK » Fri Mar 20, 2015 11:56 am

I am working harder to figure out the question then the answer!

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Merlyn
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Re: R -410a versus NH3

Postby Merlyn » Fri Mar 20, 2015 12:22 pm

This was the thing shown to you by the next apprentice up who was "handing over" to you. This was performed in all aspects of the job, in the engineroom, machining, white metalling, dodges, perks short cuts etc. skives included. I am sure anyone who operated NH3 compressors in particular must be aware of this. It had nothing to do with the operation of the plant as such, it was a kind of bonus thing which really worked every time. As usuall health and safety boys would have had a fit concerning this but in those days it was nothing like now and in a lot of ways certainly more of a laugh and as such perhaps more interesting. Bit like the saying, "the old songs are the best" perhaps.
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Re: R -410a versus NH3

Postby Revolver » Fri Mar 20, 2015 3:44 pm

Tension springs let go, racing away, plus gas is seeping in further...
No Q&A in the exams about it, but it might help you study for them.

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Re: R -410a versus NH3

Postby JollyJack » Fri Mar 20, 2015 7:36 pm

NH3 is deadly, but it's cheap, so that's what's used on freezer trawler factory ships. What is life worth when you can save a buck or two?
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Merlyn
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Re: R -410a versus NH3

Postby Merlyn » Sat Mar 21, 2015 12:15 am

The reason it's not in the Q'& A is because it was a personal thing unbeknown to management and was handed down by the apprentice who had done the job before you. In other words it was supposed to be imparted by those " in the know" and as such I am hoping that someone out there would say ah, yes, funny one that and to that end I am still hoping that perhaps maybe some of our old apprentices might read this site maybe?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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D Winsor
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Re: R -410a versus NH3

Postby D Winsor » Sat Mar 21, 2015 6:27 am

Outside the toxicity of the gas, there is is a major defect with NH3. If you check the entropy curve for NH3, ammonia will not condense into a liquid state at temperatures above 90 deg F making the gas very inefficient and ineffective as a refrigerant when water used to condense the gas back to a liquid is very warm.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

Revolver
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Re: R -410a versus NH3

Postby Revolver » Sat Mar 21, 2015 8:14 am

I'm not someone with NH3 refrigerant experience of course, but from my mostly-completed science degree majoring in Chem I understand you can make a pretty effective drink from some compounds containing. Used from curing hangovers or nerves to even being used as an old form of red bull, if you will?

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Big Pete
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Re: R -410a versus NH3

Postby Big Pete » Sat Mar 21, 2015 9:58 am

I think Revolver may be hot on the trail here, congratulations!
Like JK I have a problem understanding what the questions are, they are so vague..
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Merlyn
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Re: R -410a versus NH3

Postby Merlyn » Sun Mar 22, 2015 3:24 am

Yes BP you are correct in your assumptions, Revolver, with no NH3 experience has solved this problem that no one else out there could. The distict advantage over Freon is it is the worlds best instant cure for a hangover. Shame on all you NH3 people out there when a self confessed no experience person has cracked this question. He got the answer from a Chemical 1 course, a clear case of. "The pen is mightier than the sword " here all right. Sorry about the way the question was put but anyone who was in the know would know the answer instantly and I really could not give further clues without giving the game away. When being taught the NH3 plant and being shown around by the apprentice who you were replacing when the Chiefs back was turned you were shown all the short cuts and dodges. Talking out of the side of his mouth the apprentice would ask if you knew about the instant hangover cure. When you said no you were placed by the compressor HP discharge valve and the gland nuts would be slacked off resulting in a face full of ammonia, reeling backwards, eyes streaming this was a "first " and never to be forgotten experience. So congrats to Revolver and all I can say further is for him to put his tutor back on the Xmas card list as on this occasion certainly the pen is mightier than the sword.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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D Winsor
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Re: R -410a versus NH3

Postby D Winsor » Sun Mar 22, 2015 1:59 pm

I should have mentioned in my recent post on NH3 as a refrigerant The head pressure for the gas to condense into a liquid would be extremely high (above 1000 psi) and would be impossible at coolant temperatures above 90 deg. F
Troubleshooting 101 "Don't over think it - K.I.S.S. it"


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