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Ahmed Najeeb
12-01-2015, 08:04 PM
Hello everyone
I am a fresh graduate who had the privilege of working with Fujitsu representatives, and i am currently installing new VRF system at headquarters( for clarification i am not the site engineer, i work in association with a sub-contractor hired by the representatives to install the units), So after successfully completing the installation, the owners requested some changes for the pipes routing, so the contractor performed a pump down for the refrigerant in the indoor units; but he mistakenly left the three way valve open, so after the rerouting was done upon performing leak test with nitrogen gas some gas leaked inside the outdoor units.
So now we need to change the R410 refrigerant occupied at the outdoor unit completely, and my question is upon doing so what will happen to the compressor oil, also i am requesting to know what are the vacuum pump adapters, and how are they used?, and lastly if i were to replace the traditional leak detection method using soup, would what be the perfect leak detection device that i could use for detecting both nitrogen and R410
sorry for the long post and hoping soon answer.

Tayters
12-01-2015, 10:58 PM
Hi Ahmed.

What is the model number? Newer models (V2) had no facility to pump down.
Anyway, you need to vacuum from both (or all 3 ports if VR2). I would then let the refrigerant in both ports until you need to run it to get the rest in. If you are worried about flushing oil out then let the gas in slowly.
What do you mean by vacuum pump adaptors?
Leak detection with 410 and nitrogen best using electronic detector as well as leak spray. What do you mean by 'detection using soup'
Thanks, Andy.

Ahmed Najeeb
13-01-2015, 06:46 PM
Hello Andy sir
sorry for late reply but i was at work, and thank you so much for your reply.
okay i am going to further extend my elaboration, we have three outdoor units which forms the combination AJH288LNLAH the outdoor units are V II tropical series, and they are AJH126, AJH90 and AJH72, so like i said the owners requested some pipes rerouting and so the sub-contractor performed a pump down where he stored the refrigerant in the condenser of the master unit AJH126, by the time this happened i wasn't yet assigned there so i haven't witnessed it personally, so he left the three way valve opened and so during leak test with nitrogen gas some nitrogen leaked inside the unit, so now we want to recover all refrigerant trapped inside because it's contaminated with nitrogen, now please you must notice i am new so could you explain to me in specific details what do i need to do so the oil wouldn't flow out of the unit, and also should I open all valves of three units or just the master unit will do for i am not sure whether or not there is refrigerant in there?
My company uses very outdated and traditional procedures and i am trying my best to elevate the work standards, they currently use soap foam (literally liquid soap mixed with water to form foam), and they apply it to the brazing area and if it bubbles then it means troubles, and this method is tedious, time consuming and highly unreliable, like for the last two days we've been searching for a leak that caused the gauge to drop from 41 bars to 39, and eventually we found the gauge to be faulty but the soap foam sprayed on it indicated otherwise because no bubbles ever were formed, so my question is what's the best electronic leak detectors to use and these leak detectors can they indicate R410 leak or just nitrogen.
and for my last question; in the manual of installation it says that you could use a conventional vacuum pump suggesting that fact that you use it in association with a vacuum adapter, so my question is hat the hell is that, and also is the use of check valve is a must because they don't use check valves during vacuuming, and I want to force the use of it but need a strong argument to support my request or else will be disregarded.

Brian_UK
13-01-2015, 08:48 PM
Recovering the refrigerant from the system will not remove much, if any, oil. The oil only moves around the when the refrigerant is being pumped around in normal operation.

I'm sorry but I haven't heard of a vacuum adaptor. A non return valve is good practice when using a vacuum pump. The reason being that if the pump should stop when in the process of evacuating a system then the oil in the vacuum pump could be sacked backwards into the system.

Ahmed Najeeb
13-01-2015, 08:58 PM
Thank you very much sir Brian for your most appreciated reply, but could i know what's the correct procedure of perform the recovery, should i connect the vacuum to the two ports of the outdoor unit or just the gas port? should i open all three way valves of all outdoor units or just the master unit, i am sorry for seeming incompetent but i haven't witnessed this procedure before and like said it's only been three months since my graduation.
Thanks for the info for non-return valve i will try to persuade them in making the investment.

Tayters
13-01-2015, 10:22 PM
Not sure what the vacuum adaptor is either. I've checked the English manuals and there is no mention of them. Either way as long as you vacuum from both service ports there should be no issue. As Brian says, a non return valve would be a good idea just incase your vac pump oil had any ideas of jumping into the pipework. Save a whole load of grief. Think some vac pumps have them built in.

There are high and low ports inside the unit (at least for the non tropical version) so you can reclaim through these. All 3 units need reclaiming as you will need to recharge the correct weight. Then you can open the all the service valves up and vac from one set of high and low ports. When you are satisfied on the vacuum (get the boss to get a torr gauge!) add new 410A. You may need to run it in cooling and slowly and any remaining refrigerant through the suction pipe.

There is a function setting to open up the expansion valves but as long as you vac through high and low side then there should be no need to do this setting.

Soap is a cheap way of looking for leaks. Used it myself once on a display chiller coil. Found there were too many small bubbles everywhere, probably bit too keen with the washing up liquid, but did find the leak eventually. Must be time consuming with all those joints. Best of using an electronic detector. I prefer the Dtek (http://products.inficon.com/en-us/Product/Detail/D-TEK%20Select?path=Products%2Fpg-ServiceToolsforHVAC-R) but as long as you get a half decent one, find the area it goes off the narrow it down with bubbles, be it soap of preferably leak spray. Electronic detectors sense just refrigerant. Don't think there is one that detects nitrogen especially as the air we breathe is made up of 80% of it. Perhaps an ultrasonic one is more what you would need.

Good luck in getting the boss to up his standards. Never found anyone who had any success with that mind, all about the money...

Ahmed Najeeb
14-01-2015, 10:45 PM
Thanks once again sir Andy for you reply, truly trailblazers like yourself are the kings of HVAC.
i found out what they mean by vacuum pump adapter it's a joint you use to connect your old vac pump with the new R410A gauge as it has different ports than those encountered with R22.
Yes in the tropical series there is a high and low pressure ports just is in the regular one, and i did as you've told me i opened these valves and connected them with a hose and of course due to pressure variation contaminated R410a found it's way out of the unit, thank god it isn't R22 or i would have felt bad about the ozone, so now the pressure inside and outside the unit is the same so now i will connect the vacuum pump and reclaim the few remaining refrigerant, then will open the three way valve and evacuate the entire system, then add refrigerant.
So i have this other matter this sub-contractor dude he uses flared joints with soft pipes, and i know that it should preferably be joins and elbows instead, but he just insists on using flared joints to minimize leakage chances and speed up his work, despite me providing all the joins and elbows he would need, so i want to know is it safe to use flare joints in a system that can reach 40+ bars, or i am just exaggerating and should take it easy.
yeah the boss denied both my check valve and electronic leak detector request, i just learned that lesson the hard way. and btw they don't even have a vacuum gauge, they just use the regular gauge which indicates pressure till -1 bar, though it clearly states that you should vac till -1.7 bars in the manual, their response is that we will just evacuate for complete six hours which should be enough.
so one last request is i really want to know the fully thrall operation characteristic of the inverter of the outdoor unit, i want really in depth information of every single details from the second the current enters the outdoor unit till it's passed to the compressor, so i was wondering if you have such a documentation, or if you could elaborate for me, and if you have any pictures or some sort of guide you've kept during your practice for the installation process, just some guiding tips and preferably visual ones, because i am interested in both the technical part as well as the part, i know this is too much to ask for all at once and i am sorry for this but i am really eager to know all aspects pertaining to this VRF as quick as possible, so i can move on to chillers my true passion.
sincerely Ahmed.

Ahmed Najeeb
15-01-2015, 05:31 PM
So today when dong the final touches on the outdoor unit, we were supposed to vacuum the remaining gas from the unit, so i told him that we should evacuate from the Hi/lo pressure ports with the three way valves closed, but he insisted we open them, not only that he insisted on evacuating from the three way valve it self, as soon as he opened it gas and oil came flying high and so much oil was wasted, so he decided to do it my way but from only the low pressure port and i told him we have to connect both, he said it is a closed loop it won't matter and he evacuated till just -60 kg/cm2, is this oil loss significant, will it affect the performance of the compressor?

hyperion
15-01-2015, 06:00 PM
Think that you should have used a reclaim machine to recover all of the refrigerant/nitrogen and opened all of the valves to ensure that there was no refrigerant or nitrogen trapped.
It is going to be difficult to estimate how much oil has been lost as a small amount makes quite a mess.
Whilst there is nitrogen/refrigerant mixture still in part of the system, it will be very difficult to achieve a vacuum of any sort.
Preferably, you will need to add the oil carefully once you have removed all of the gas pressure and before you start the vacuum pump.

RANGER1
15-01-2015, 09:54 PM
http://www.refrigtech.com/Product/Leak_Detectors/Big_Blu/bigblu.html