How to monitor/evaluate refrigerant quantity running in the cycle?

[antonio nunes]

Hi everybody--recently graduated marine engineer and now responsible for maintenance of all refrig. units on bord a passenger vessel, I must admitt equations and maths aren´t just enough.

During the last 2 months i´ve been solving the ocurring malfunctions by filling refrigerant and "forcing" heating coils to de-ice the evaporators in some of the freezer rooms more frequently.

At the present moment I would like to know how to determine the exact(as exact as possible) quantity of refrigerant running in each single mainline........I do I do that?
-calculations?
-can jeg meter it?
-other alternatives
...........................................best regards Ant

[sedgy]

hi ant .
the tried and tested method of determining how much refrigerant in each system, is well documented = reclaim and weigh each bottle< what do you mean by mainline ?< hope this explains your question ,
sedgy,

[antonio nunes]

Hi Sedgy--thanks for feedback. With maninlines i ment the the different refrigerating circuits..each one with own compressor+evap+condenser etc.
..yes, I was looking for an easy way out on accessing precisely how much refrigerant i´ve got within the system.
So, if I understood you right, the only way is to recover and weight it outside the system...bad news indeed
...happy new year

[install monkey]

if u degas a system thats at its setpoint then u can recharge it quickly whithout affecting the stock in the freezer/fridge. but be aware that ur reclaim rig will hold refrigerant in it

[chemi-cool]

I will support these distinguished members and add that its common practice to have a label with the amount of refrigerant in the system, just as there is a label tells you what refrigerant is in the system.

Get a good recovering machine.

[antonio nunes]

...much obliged you all. The only reference i´ve got concerning the capacity is the one the systems were designed to..and a logg-book were all Kgs of filled up refrigerant are noted down----an average of 5 Kg / 1½ month. Leak detection distributed for 11 decks is practically impossible---well.. sooner or later all will be running smoothly since there´s a solution for every single problem. b well

[Peter_1]

Refilling without repairing the leak is not allowed for fix installations. Is your installations a fixed one?
Not finding leak is impossible. With a good leak detetctor you will find certainly some leaks. Or add some additive (mercaptame) so that a stinking odor equal to that of propane or LNG comes out the system through the leak.

Eventually divide the system in sectiopns and look where pressure drops after some time.
When is there enough gas in the system? As soon as your SH comes within the desired, normal range, you have enough gas to feed you evaporator properly. All what you then additionally charges is overcharge and doesn't benefits the system.

[antonio nunes]

Thanks,Peter...since we are talking of a passenger ship with bares and restaurants distribuited on nearly all decks, the smelly additive is per definition not such a good idea.
In the other way a pressure drop survey is indeed feasable.
On the SuperHeat matter...5-8K temp difference between evaporator outlet and compressor suction inlet, wouldn´t it be suitable, and a good indication that the cycle is proper fedded?
Thanks in advance..........best regards