My passion is learning and as with any education, cost is a factor.
In this case it is the hardware cost which I want to share and why those hardware must be made available for specific task.
I am fortunate to own a diving air fill business for a few a good years to practice and understand why super clean air and super dry air is a must for safety of the divers ( SCUBA ) and fireman ( SCBA ).
Clean is easy to understand, contamination like CO ( carbon monoxide ) will kill a person. The deeper the dive, the higher the partial pressure the diver breaths at, the same small CO amount will be
be doubled at per 10 meters or 33 feet underwater.
Per extra 10 meter deeper in freshwater ( seawater is bit higher pressure ), a diver experience 1 extra ATM or 1 BAR (easy to visualize ) or 14.5 PSI ambient pressure and his breathing air must accommodate this pressure
increase by his 2nd stage regulator ( at the mouth ) by raising air pressure higher by 1 ATM over ambient sea/fresh water pressure. We human can't breath well if mother earth does not produce that 14.5 psi air pressure over us.
Hence climbing to very high altitude we can't breath well as the ambient air pressure goes lower and lower.
Now the super dry air part. Firefighter in cold countries say in winter at zero Celsius (32F) or colder, will have his breathing air regulator 1st stage freeze internally and air will stop flowing if the air in his SCBA is not dry enough.
The same goes for ice diver ( SCUBA) but the beauty of water be it seawater or a lake freshwater, it is never colder than 1 Celcius when in water state.
This SCUBA or SCABA is a 200 BAR / 3,000 PSI tank ( some countries uses 4,500 psi tank for SCBA and/or SCUBA ) has 2 pressure reduction stages. 1st stage ( at the tank ) to 2nd stage is a 200 BAR to 9.x BAR.
2nd stage ( at the mouth ) is depending on ambient pressure be it air or water surrounding the firefighter or diver, it has to be equal to a person breathing in a nice sea level.
Why do I discuss SCUBA and SCBA ?
It is easier to understand compared to R134A refrigerant which is a unique liquid-gas thingy and can boil at -26.1C or -14.9F at sea level . DAMN !!!
Anyhow, pressure reduction cause temperature drop and 200 BAR to 10 BAR can create coldness at the orifice of regulator 1st stage down to -30C cold.
Therefore the air dryness to be achieved for firefighter in cold countries is to be drier.... at approx -50C dewpoint as maximum wet !!
Dewpoint is easy to understand, -50C dewpoint means at this cold-ness and when colder say at -51C... only then the moisture in the air started to become liquid/condense and risk the freezing of the regulator 1st stage.
How dry is -50C dewpoint in terms of RH% at 25C / 77F ambient temperature ? It is only 0.13% relative humidity. Its super dry.
NFPA 1500 ( US firefighter ) request air to be as dry as -65F DewPoint or -54C dewpoint. https://www.airsystems.com/Reference...ifications.pdf
Why I am discussing dry air ?
Well, ambient air has moisture and this moisture is what kills your R134A HVAC system.
The air even if there is no moisture itself is non-condensable gas and will cause poor HVAC performance. Simple explanation is, air can't be GAS-LIQUID state like r134A in a HVAC system, so it screw up the refrigerant performance.
We get cold by removing heat using r134a superbly unique conversion GAS-LIQUID-GAS-LIQUID.
Here is where the HVAC system being "dry" is different than diver air being "dry".
In breathing we keep the air as air, but only remove the water moisture and all other bad gas. Primary target is water moisture first, for prevention of freezing and 2ndly for CO catalyst like Hopcalite,
which wont work if air is not very dry . https://en.wikipedia.org/wiki/Hopcalite
In HVAC system being dry means : really zero air if possible and this means very very good vacuuming system is to be used.
I never took a deep look at what vacuum really is, until I learn of HVAC system.
Vacuum is a reduced ambient pressure, as simple as that. There is no such thing as vacuum pump is a sucking pump like how we see air compressor pumping air to higher and higher pressure.
Vacuum pump creates low pressure region, thus air molecules at higher pressure region will migrate to region of lower pressure, as simple as that.
Maximum vacuum is when there is no air molecule at all in a container and it can never be achieved to a 100%.
We can achieve with a U$2 china hand pump to create 2x ambient air pressure and spend a bit more $ you can make 8x ambient air pressure pump of low volume per minute.
Units of vacuum at sea level is -1013.25 millibar as 100% perfect or -14.6959 psi or -29.9212 inchHg. You can use Absolute scale and no need for minus sign.
Since we need better resolution than these numbers, we use microns of mercury for imperial countries or Millitorr for SI countries. We use 760,000 as mercury microns of air pressure at sea level.
Since Mr. Carrier is the grand daddy of air-cond system , I will use microns of mercury. All my special tools are US sourced too anyway.
The regular vacuum gauge using inch Hg unit. Some uses minus sign, some doesn't. Its okey as long as you know how to read it.
Now, the target deep vacuum is 500 microns or better at the HVAC system port itself.
How the hell can we see that value using an analog gauge ?
I use my RobinAir 3/4HP vacuum pump for vacuuming down underwater camera housing to test for leak by way of seeing if there is a vacuum decay over X minutes. That was why I bought it many many years ago.
All I need is -25 inch Hg and that is enough.
Later I used this vacuum pump for radiator air pocket removal and I accidentally sucked coolant into it ... LOL.
The intermediate liquid catch/trap bottle was too small and this pump is so fast.
I overhauled the vacuum pump all rubber seals and assume all was good. Sure in analog gauge visual all looks good.
I want to learn of HVAC and I must have this micron gauge.
Hold and behold , my Robinair accidental ingesting of coolant has scored a tiny tiny bit of its dual stage vacuum pump head and best I can achieve is no better than 1,000 microns and not stable too.
I would say 2,000 microns as stable. USELESS FOR HVAC WORK !!!!
So I must buy a new vacuum pump ..DUGGGGGHHHH
And I did got it yesterday.
Holy cow, 9 microns at the pump head..YIPEE !!!!
This is a better china made unit, not garbage unit. Advertised as 15 microns at pump head and say 5 micron gauge accuracy, this freaking 15 microns pump is so smooth and powerful and affordable.
US$194 only locally and will be locally US$450 - US$550 if RobinAir 8CFM which is also China made for today's range.
Amazing. See their products here : https://www.worldvalue.cn/
===================
Now, using pressures vs temperature ONLY to verify PROPER refrigerant gas charge ? Nope, it is not possible and more so with today's variable displacement/volume compressor which is computer controlled
and not the simple fixed displacement compressor with ON-OFF where OFF being zero pumping or ON being maximum pumping.
More hardware needed to do this and this is very expensive to do it responsibly and accurately for a DIY who does his 2 cars say once a year.
01. IF USA resident abiding EPA rules. All refrigerant removed must be captured and sent out to recycling center or HVAC workshop willing to collect your refrigerant for a fee. How do we do that hardware wise ?
02. ALL COUNTRIES : All refrigerant removed must be measured for its weight and verify against OE table. W212 most models single evap car, are 590 grams R134A. How do we do that hardware wise ?
03. ALL COUNTRIES : All refrigerant removed may/will contain compressor oil and whatever quantity being removed, must be returned to your car HVAC system. DAMN !! How do we do that hardware wise ?
Most W212 models are filled with 120ml/cc of compressor PAG oil by MB.
I believed there is no oil separator on this unit. Looking at its Price before sales tax and a re-branded one profit margin by Robin Air, money for money I am sure the brand VALUE I got is better in terms
of $$ spent on hardware because it is direct OE to local Indonesian distributor/s and 5% import duty only for industrial hardware in my country and 11% VAT/Sales tax which mine already included when I paid.
or get from here : https://www.trutechtools.com/cc-sear...ry&pageIndex=1
We will also need the recovery bottle. US$100 max if China made, but not stock in my country for now. DAMN !!!!
IF USA boys, you need to buy among others, from here US$180 : https://www.grainger.com/product/GRA...Cylinder-4LZH2
or
So, how do we avoid removing compressor oil during recovery ?
Get this refrigerant sight glass and learn of how to do it properly on your car.
Below is a good guideline but you need to google more.
And we need a very accurate refrigerant scale. For me US$221
This is a 50KG unit. Older model from VALUE China. But this has a solenoid to trigger shut down when certain quantity reached.
I tested ts accuracy last nite and I am so impressed at the progress cheap semiconductor has brought us for the weight sensor.
VALUE VES-50B Refrigerant Scale............ I am beginning to have more trust with this VALUE brand as of today.
Supposedly 0.05% accuracy or 2 grams. To US boys, 1 ounce is 28.35 grams.
First I verify weight of the test objects using Tanita 2,000 grams scale. This is also a 2 grams accuracy and Tanita is Japanese brand.
I get 1 gram overall accuracy.
So now, let's test the China made unit.
Above test is for object under 1KG. Impressive for a 50,000 grams scale to be this accurate at 700 grams worth of objects. Target is 5 grams maximum deviation.
Lets use a heavier object which will be close to a new 30lbs bottle of r134A.
Holy cow, 5 grams accuracy target can be achieved !!!!!
Here is an example if we as a car owner ( Mercedes too ) does not understand and not wanting to learn, we can get whacked by a car care workshop using the best US$22K Snap On dual gas 3R HVAC machine 334B.......... because the hvac operator is not properly trained and the vacuum pump of the 3R machine is not well maintained too.
I guess as Tom Lech put it, spend money to train your staff at proper HVAC training seminar/school is so true and a must. US$22K machine is useless if operator is un-trained. https://www.youtube.com/@coldfinger459sub0/about
Click the youtube link on the above image and you will go direct to utube.
==================
Lazy to read HVAC techy the provided fill charge label and probably grams in an alien word to him
So this is a W166 without rear EVAP
2.03 lbs recovered/pump out
2.08 lbs recharge/put back because techy recalled 2.08 was the recovered.
2.03 or 2.08 are WRONG !!!!! Fully evacuated/recovered system W166 is to be put back at 1,050 grams or 2.314 lbs !!!!
This W166 assuming MB USA done the refrigerant charging well and this W166 first ever refrigerant recovery is on this video, this W166 has lost 12.29% since brand new. Well natural leak rate of any dynamic seal is real.
=========================
Techy does not understand that 2.2% air is already BAD.
Probably bad practice not evacuating the hose using the vacuum pump properly before use.
Dont get confused by 100% r134A and then 2.2 air is equal to 102.2% which does not make sense being over 100%
The 100% r134A is the purity of the gas. 2.2% is the overall air content within this W166 HVAC system.
When you go for EPA HVAC training, they teach you all this.
See techy is honest but does not realize he should be doing proper evacuation of the hose to avoid air* as contamination ( *non-condensable gas )
Can zero % air be possible ? Hell yeah, if all done properly. Below is from Tom Lech channel.
Air can't do the magic a refrigerant can do with GAS-LIQUID-GAS-LIQUID transformation. R134A can boil off or be vapor at -26C or -15.34F at sea level atmospheric pressure.
This unique property of refrigerant is how heat is removed from our car interior.
===============
Lazy azz, typical vacuum setting of 20 minutes is being bypassed to be 10 minutes.
20,860 microns after 10 minutes is most likely a poorly maintained vacuum pump inside the Snap ON 334B.
15 hours is the oil change as per Snap On user manual. I cant find this top end dual gas user manual yet, I got the Snap On single gas user manual.
This is TEXA brand and model MB approves. This is a very new machine, so very well maintained and the built in vacuum pump still works well.
Too bad Texa vacuum gauge is not a micron gauge and 1 millibar is the lowest it can go.
Usually 2,000 microns to 500 microns is the slowest as it is not easy to evacuate such low count of gas molecules is using 5 feet hose and so small at 1/4".
When I admire your devotion, I am getting impression that you are overthinking some issues.
First in scuba at certain pressure oxygen becomes poisonous gas. That is why air-supplied scuba is limited to 40 m, when such phenomena can start. CO is poisonous even at atmospheric pressure but it takes some absorption to take the effect.
Than W212 don't have clutches on AC compressors. At least not on American models, so I think you should double check it before making pages on pictorials, who might not apply to the situation
Vacuuming AC system is not done for reaching lower pressure, but for extracting all the moisture from the system.
Living in dry-weather Las Vegas, once I refilled the system without vacuuming and it works just fine.
Bear in mind that it is well proven that human perception drops drastically after reading 30 lines of text.
Making long topics, you are loosing lot of readers who will get bored 1/2 the way.
Have fun on your research.
When I admire your devotion, I am getting impression that you are overthinking some issues.
First in scuba at certain pressure oxygen becomes poisonous gas. That is why air-supplied scuba is limited to 40 m, when such phenomena can start. CO is poisonous even at atmospheric pressure but it takes some absorption to take the effect.
Than W212 don't have clutches on AC compressors. At least not on American models, so I think you should double check it before making pages on pictorials, who might not apply to the situation
Vacuuming AC system is not done for reaching lower pressure, but for extracting all the moisture from the system.
Living in dry-weather Las Vegas, once I refilled the system without vacuuming and it works just fine.
Bear in mind that it is well proven that human perception drops drastically after reading 30 lines of text.
Making long topics, you are loosing lot of readers who will get bored 1/2 the way.
Have fun on your research.
Think of a person using a ruler with 1mm precision and then need a micro-meter or a dial-gauge which can do 1/1,000 millimeter for works demanding such accuracy.
I too never knew about vacuum micron ( imperial ) instrument, because I never needed such resolution, until I find the need.
Think of oscilloscope vs a DMM. Why do we need it for ?
Why do we need 1 second of time to be seen at 100,000+ data points on a scope where the regular DMM see it only 4 data point per second ? CAN BUS data is why .
Technically, my sister and her daughter with granddaughter made me great grand pa at young age of 68.
Still, when I admire you devotion to do extensive research on the car, your topics exceeds perception of about 99% of readers here.
I have education to read and understand what you are doing here, but why would I waste my time for it?
You might seek engineer's forum for sharing the results or your hobby, but you will not find lot of understanding here, even some members will give you thumbs up for something they can't comprehend.
My personal advise - make shorter topics and wait for members respond to carry it farther.
Flooding the forum with texts that not too many can understand can go only so far.
K wrote : Still, when I admire you devotion to do extensive research on the car, your topics exceeds perception of about 99% of readers here.
I have education to read and understand what you are doing here, but why would I waste my time for it?
What is wrong with sharing ?
I don't target Thumbs Up or anything of that sort. I like sharing mistakes and progress I have learnt.
This way when and if other members decided to do the same, he/she can avoid the mistake/s I made or learn along in simple terms what I learnt.
What is the most complex, expensive and guarded secrets to DIY our cars ? The way the software and electronics is integrated in our car, that is one field I am weak because me is IT stupid and the hardware required is not cheap.
There is a limit to the DIY we can do for some of the components in our car, example the complex ADAS system where the workshop calibration device to do those, many are not DIY-able from a regular John Doe $$ and garage size, unless
we are Jay Leno garage and wallet size.
One information you will almost not able to extract from members here is the coding, because those members who are good at it makes a living out of it. We have to respect that and simply pay.
K wrote : You might seek engineer's forum for sharing the results or your hobby, but you will not find lot of understanding here, even some members will give you thumbs up for something they can't comprehend.
My personal advise - make shorter topics and wait for members respond to carry it farther.
Flooding the forum with texts that not too many can understand can go only so far.
I don't understand your thinking " make shorter topics and wait for members respond to carry it farther." Why must I wait for a response ? ...where I posted the information not for the response, but for the mean to share.
If members don't like it, simple...don't read it. If members don't understand it, they will try to learn when and if the need arises.
There are many here who loves learning, but there are much much more transit members where they only hang out when they have issues and expect assistance.
"Flooding the forum with texts that not too many can understand can go only so far." Is letting other members learn a better practice and lots of information comes along with it to explain why the trouble I have to go thru in order to do best practice for my own car, is that a SPAM /Flooding ?
What did I do wrong ? What loss have I caused this forum ?
I don't ask for sponsor to buy all the gear, its my own $$.
If say BenzNinja one day decided to retire coding cars and spread his know how in this forum for the good of all members, will that be a flooding/spam post ?
99% of members here won't understand what he will explain if deep software stuff and how many members here has a C4 multiplexer or equivalent ?
This excellent thread as an example : https://mbworld.org/forums/e-class-w...ofit-w212.html
Even if one has the mechanical skill to do it, has the C4 multiplexer, has the most stable Xentry..........without those special coding files and enough IT know-how on Benz cars, we can't do it.
I see SUNILP post as excellent, but I can't do it too ...yet, albeit I have all the required tools now.
If I gain knowledge enough like SUNILP, will I post a complete explanation the IT/Coding side of things ? You bet !
Now the HVAC part.
The know how is available from commercial sector. This is a very big industry and many webminars available for free.
We can buy the HVAC book too, unlike coding MB cars, you wont find a good book on coding, even if you do.... where are the coding files ?
The proper good materials on HVAC is so abundant, and no special IT skill required, awesome for me and hence I try going deeper into it.
The hardware are available in open market, no need Locksmith Licence or workshop licence or annual licence yada yada... beautiful !!!
I like diving, the science of it and not the business side of it.
So by 1996 I was a qualified PADI Dive Instructor, spent lots of $$ to log enough dives to qualify to enroll into the program. The education fee was not cheap back then.
By 1998 I stop teaching, I got bored because I rather dive more for the hobby than to teach.
By early 2000 I started improving dive safety for my own group and community by using advance rescue devices.
Lost divers at 3 to 10 people a year is common in Indonesia, usually in Bali. They drift and died eventually days later on the surface from lack of drinking water.
Poor surface support, crazy 3+ knots surface current and sudden down-current is the usual cause. This is open water dives, at the Indian Ocean and must use dive boats.
Early 2010 I wanted to learn more of super clean and super dry air purification for diving.
I was fortunate to get in touch with a doctor who is a technical diver. He is the Peter in this publication https://pubmed.ncbi.nlm.nih.gov/22692708/ https://www.dhmjournal.com/images/Jo..._Vol38_No3.pdf go to page 145
He was my mentor when I built my air-purification air-fill station for commercial use. The only air-fill station in the country with on-line dew-point sensor, CO sensor and CO2 sensor and 2 big filter towers.
I did not make money for the 5 years this air-fill station was running, I did not loose much, but the gain of knowledge is priceless. The sensors are damn expensive and some are 2 years life span only.
I was selling the air fill at only at US$2.00 for 80CFM dive tank and other reckless low-quality-smeely-wet air-fill station was charging US$1.20
Florida at that time I believed was selling US$5 there about for the same air-fill.
The sad thing was, all of the diver masters or dive guides when they know the air-fill was done by my station , they will grab it first and give the reckless air-quality one to their paying customers
I wonder how cheap their client well-being or safety/life in their eyes were... by their willingness to save a mere US$0.80 per tank ??
I like yachts and was wanting to learn more in early 90s, I then enrolled in Westlawn long distance and there was no internet yet back then. Postal service only. https://www.westlawn.edu/
This small school has produced a few US top Naval Architect for pleasure craft https://www.yachtingmagazine.com/his...ne-technology/
I did not complete the 3,200 hours 4 years course, I only took the part I need.
I did well selling and maintaining yachts mid 90s to late 2010 because I understand the mechanical and hydrodynamic part of it and the stability in rough waters.
Today I only handle special long time client's yachts only or yacht's which tickle my mechanical itch.
==========
I did not do well in high school, I hate school. Only physics was my favourite subject, the rest I don't care. I was too busy street racing and getting chased by traffic cops , me was a 15 years old with bogus driver licence.
But when I like something, I will chase the know-how to the last bolts and nuts.
One can do well if one put aside the profit oriented thinking and go full blast based on passion and hungry for know-how.
Yes, it is.
I am just pointing, that when "Forum" usually is institution for open dispute, long topics flood it and make dispute hard to follow if not impossible.
You are making wrong conclusions and open dispute would allow you to catch them, but the way you do it, it is just preaching.
If you have fun with it, go for it, but I don't see that much technical value in it.
01. Vacuum hose size and loss of suction power from small standard 1/4" hoses, well before testing on car HVAC system.
02. Checking all my valves and hoses end seals for vacuum integrity.
===========
01. Vacuum hose size and loss of suction power from small standard 1/4" hoses, well before testing on car HVAC system.
Learning of the current gear I have and its limitation.
3/8" vacuum rate hose with one end being 3/8" and one end being 1/4" will arrive at least 2-3 weeks more.
When the time come, I will do single hose deep vacuum and will not use gauge manifold set. Vacuum pump direct to LP port in the car.
Baseline Test
Extra 2.8 minutes wasted to get to 9 microns from a mere hose length so short, I think hoses ID are rough surfaces.
Current 1/4" hose extended test.
SUMMARY
AA. Single 150cm hose with core depressor removed, if evacuation/vacuuming done for 10 minutes best achieved 233 microns, and with such poor rate of 2 microns per minute evacuation because of
the hose itself is too small a diameter, $$ invested in a 8 CFM pump will use so wasted as to get 500 microns at car HVAC system will take too long.
BB, If vacuuming done using gauge manifold, 2 of 150cm hose will be involved, the result will be totally not useable.
If core depressors not removed from both hoses , below :
If core depressors removed from both hoses, below at 8 minutes duration.
514 vs 468 microns. Damn, 56 microns lost from such a simple 2 of valve core depressor dot.
At such slow rate of 5 microns per minute and will be lower as deeper vacuum achieved, it will take hours and hours to "dry" my car HVAC system with such severe efficiency loss
from these 2 small hoses.
A well used ( dry ) hose and in area with less humidity than my city, this guy can get better result but its a single hose end test too and not on a car HVAC system, yet.
Good vacuum hose is a must have, otherwise vacuum pump investment is wasted. He is using a 6CFM and mine is an 8CFM.
===========================
02. Checking all my valves and hoses end seals for vacuum integrity test.
I fear my ball valves will fail as they are not the high quality one, and indeed, all failed
Vacuum failure contribution/s : The blue color big knob valve at gauge manifold. This is low cost China made, brand is VALUE .
Low quality MasterCool 2 of ball valves from this test kit :
+-425 microns to 852 microns in a mere 2 minutes. FAIL too !!! At least now I know how to be extra careful when using this kit to see refrigerant oil color as it needed to be vacuumed down before use.
Duugggghhhh !!! Got to invest, again !!!.... in a good vacuum rated Appion CRT ( valve core removal tool while HVAC under pressure for 1/4" SAE flare fitting ) Kit,
which can also be used as isolation valve and 3 way valve or micron/pressure gauge attachment.
This is a 2 hose vacuuming method and these are vacuum rated hose, the red one is a 3/4". 180 microns in less than 5 minutes and the HVAC system is bigger than my car. No gauge manifold will ever be used as it is a parasite for vacuum work.
I will smile ear to ear if I can get 250 microns with such method but on a single 3/8" vacuum rated hose, at 1 hour on my car.
Single hose TruBlu brand silicone one, a 3/4" size vacuuming method is also popular.
Below test has a very good vacuum decay result of only +20 microns or from 180 to 200 in 10 minutes... DAMN such a tight ball valve !!! Those are Appion CRT valves.
I shall re-test again and update when my 3/8" yellow Jacket vacuum hose and the vacuum rated Appion CRT valves arrive.
I still can not get my hand on a 30 LBS recovery bottle
The Recovery Machine, I got it already. It is not bad. Oiless compressor type, I guess 300 hours this will be a throw away unit but that is more than enough service life for me to use for the next 10 years
at even 10 cars a year if my friends want their car HVAC to be my test pigs too...LOL.
This Appion CRT, too bad it does not make one for car r134a system, otherwise it is good to have.
This is multifunction tool actually.
I already ordered a core removal tool for r134a....from Aliexpress, China made one and hoping it will last 20-30 uses.
MasterCool has one , but China made too and sold at 8x the price ...LOL
The 3/8" yellow jacket vacuum rated hose arrived a few days ago.
It works well. , down to 41 microns in 10 minutes yipe !!!!.....but factory QC is kinda bad, looks like Godzilla took a bite
Indeed, looks like Godzilla took a bite
Since I can't get the recovery tank, I decided to re-purpose my 13 years old 63CF scuba tank which I will retire in 2025, as a refrigerant recovery bottle for the sake of weight measurement of captured refrigerant.
3,000 PSI service pressure and tested to 5,000 psi, is so much stronger than typical 400psi service pressure of commonly sold refrigerant recovery bottle.
63 Cubic Feet of air at 3,000 psi is a 8.6 liters of water content or volume. Good enough.
While a W212 single evap HVAC system overall water volume equivalent would very unlikely be above 8.6 liters, the amount of restriction from its modern super fine holes
micro channel evap and condenser is a nightmare for vacuuming.
My good valves from USA have not arrived yet, but my Ali Express toys have arrived. I get to test them. Its not bad for what it cost but my target is a super-tight working hardware with least permeation , let alone leak.
220 ish micron "leak" after 1 hour. The positive news is the 1 to 2 micron per minute "leak" rate for a non branded fittings.
Here no hoses involved, so not much permeation from hose material , except at the o-ring/seals of each coupler ends.
6 hours later it was 800 ish microns and still 1 ish micron per minute rise. So 700 micron rise in 6 hours or average 117 micron per hour.
760,000 / 117 = 6,496 hours it will be back to ATM sea level, in 270.6 days.
If we are allowed to use this in opposite value, its like 1 BAR loss per 270 days.
My car r134a pressure at static and at 30C is 6.6 BAR. If I use the same leak rate for fun sake, 6.6 x 270 days = in 4.89 years I loose all my r134a
I will overhaul the scuba tank valve soon to make sure I can remove the tank as the bad variable and re-do the test again with the AliExpress valve, and when the Appion brand arrive from USA
I would have proper data to compare.
Probable leaky cuplrit as circled, aside from the tank's valve.
NOTE :
I was wrong to test vacuum integrity on a valve only for the MasterCool Sight Glass, an air space so small. Micron gauge will read that super small overall air-space as a VERY big leak, if here is any permeation or leak.
Its like 1 drop of super poison in a small glass of water of 50cc is enough to kill 10 adults, but when placed in an olympic size pool that 1 drop won't do much harm.
So, based on easy shape to vacuum a scuba tank is, within like 30 minutes I can get down to 104 microns.
I am hoping on my car I can get 100 microns in 4-5 hours direct reading at HP port, while suction is at LP port to
vacuum pump with this 3/8" hose, without gauge manifold. Suction at LP port and the micron gauge at HP port directly is the most difficult low reading to get and that is gold.
I hope MB Indonesia did well when they commissioned my HVAC in 2014 with least moisture.
If there is a Master Tasos for MB engines, now there is one Master Tom Lech for automotive HVAC for us to learn from, cheers to them
Re-purposed scuba tank valve over-hauled. I get better result.
In 4 hours, the leak rate or gassing off, only 102 microns
So the china low cost valve is not bad.
The digital scale re-tested, it is doing its job. Awesome !!, 8.6 liters or 2 gallons of air by weight it can read. it will serve me well.
When tank down to 10,296 grams under vacuum LEFT IMAGE. Allow tank to "suck" back ambient air of 8.6 liters, weight of tank shoot to 10,306 grams RIGHT IMAGE or 10 grams more.
.
The US made Appion valve and Nylog seal/lubricant does not disappoint.
90 minutes of vacuuming to dry the newly arrived still "wet" Appion brand valve. 57 microns rise only in 10 hours for leak or gassing off, indeed worth the $$.
Labeled the scuba tank as r134a recovery tank
Will do the HVAC work by end of April 2023.
Must get nitrogen gas kit, as I want to replace both valve cores at LP and HP port as preventive maintenance and will not allow wet ambient air to enter HVAC system while valve core is being removed.
The nitrogen gas kit will also be good to at least test my valves and hoses to 217 psi.
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
, most of them has refrigerant analyzer which is not cheap. US$3,500 if one buy stand alone from Neuronics. https://www.valuetesters.com/neutron...1234-33-0.html
, down to 41 microns in 10 minutes yipe !!!!.....but factory QC is kinda bad, looks like Godzilla took a bite 
