How to build a Simple Recovery Unit

[_HL4E_HalfLife_]

When it come to refrigerant venting it's widely frowned upon here on XS so i created this thread for all the new guys out there (and some old guys too:D)
to show u how to build a simple Recovery Unit. All you need to build one is the following:

A Compressor of any size will do
A small condensor coil
A fan to blow air over the condensor (it doesn't have to fit the condensor perfectly)
2 access valves
A plug and an on/off switch
Wooden base to mount everything to

The pics show how it should all go together


http://img337.imageshack.us/img337/6306/simplerecoveryunitys7.jpg (http://imageshack.us)

http://img515.imageshack.us/img515/1986/simplerecoveryunit1na3.jpg (http://imageshack.us)

http://img254.imageshack.us/img254/1498/simplerecoveryunit2yn8.jpg (http://imageshack.us)

http://img525.imageshack.us/img525/2986/simplerecoveryunit3cx3.jpg (http://imageshack.us)

http://img521.imageshack.us/img521/583/simplerecoveryunit4xe6.jpg (http://imageshack.us)

I think this thread should be Stickied for all new comers to see.

[[XC] gomeler]

Would an oil seperator be advisable with a hand-valve feeding back into the suction line? I ask this as I would worry about oil contamination if I were to try and use the recovered oil. Looking forward to hearing what everyone else has to say.

[star882]

Where's the high pressure cutoff?
I would just make an autocascade to chill the recovery cylinder, though.

[n00b 0f l337]

I hope theres more coming, as in filtering, and such. After recovering refrigerant, it should be almost re-usable! Filtering, oil separation, and compressor cooling are needed so that the recovery unit is usable./

[Xeon th MG Pony]

Thats the basic system I use for one type refrigerant only. I have a more sophisticated unit for multi-refrigerants.

Didn't want to post it yet as I don't have the HP/LP switches set up yet, or any other type systems intigrated.

[_HL4E_HalfLife_]

gomeler;2202125']Would an oil seperator be advisable with a hand-valve feeding back into the suction line? I ask this as I would worry about oil contamination if I were to try and use the recovered oil. Looking forward to hearing what everyone else has to say.

Why would there be contaminated oil? nothing is being exposed to the air.


Where's the high pressure cutoff?
I would just make an autocascade to chill the recovery cylinder, though.

A high pressure cutoff wouldn't be of much use because people use differnet tanks of different sizes and of different pressure ratings but for the small systems we build they would never hold enough refrigerant to fill a tank its not like were recovering the gas from a 5ton hp.

I hope theres more coming, as in filtering, and such. After recovering refrigerant, it should be almost re-usable! Filtering, oil separation, and compressor cooling are needed so that the recovery unit is usable./

U don't need a filter! Any refrigerant u recover from a unit is already gonna be clean. As for the oil u all know that when ur recovering the gas from a system that the system is OFF so very little oil if any at all is removed from the system. Factory made recovery units don't have filter driers in them either. The only compressor cooling u need is the air that's blown over it from the condensor fan, Remember this is a Recovery unit so its not gonna be running 24/7.Even this small compressor can recover all the refrigerant from a system in less than an hour.




PLEASE REMEMBER THIS IS JUST A SIMPLE BASIC RECOVERY UNIT THAT ANYONE CAN SLAP TOGETHER TO HELP SAVE OUR EARTH.

[Xeon th MG Pony]

HP switch is a fail safe, it may be needed but it is nice to have it rather then my machine blowing up in my face due to an un-for-seen failure of some thing, or a queer event happening causing it to over pressurize!



EDIT:
for thoughs who may not know what queer means I figured I'd better clairify:

adjective
- 1. strange or odd from a conventional viewpoint; unusually different; singular: a queer notion of justice.
- 2. of a questionable nature or character; suspicious; shady: Something queer about the language of the prospectus kept investors away.
- 3. not feeling physically right or well; giddy, faint, or qualmish: to feel queer.
- there are more but not relevant about the way in which I am using the word [/QUOTE]

[hatemi]

The oil sep is gona be a must. The oil isnt coming out of the system that the refrigerant is being recovered, but from your recovery compressor. You dont want any oil in your refrigerant tank do you?

[n00b 0f l337]

^^
Yep, thats the problemo.

[[XC] gomeler]

exactly hatemi, that is what I was pointing at. I'm thinking one enormous oil seperator as I want no oil in my cylinder.

[Starkiller42]

Quick question, with tangential relevance: are those "hot shot spooter" things legit, beyond giving you a good workout? Ie could they replace the compressor in this setup? Thanks!

[_HL4E_HalfLife_]

Quick question, with tangential relevance: are those "hot shot spooter" things legit, beyond giving you a good workout? Ie could they replace the compressor in this setup? Thanks!

:confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused:

[Starkiller42]

linky:
http://cgi.ebay.com/Hot-Shot-Spooter-II-Refrigerant-Recovery-Pump_W0QQitemZ130116588803QQihZ003QQcategoryZ10948 8QQrdZ1QQcmdZViewItem

As far as I can tell they are bike-tire style refrigerant pumps. They show up on ebay every once in a while for pretty cheap prices. If they can pull a good enough of a vacuum, it just might work...

[_HL4E_HalfLife_]

OMG thats the silliest thing i've ever seen LOL i can just imagin standing there pumping that as fast as u can for an hour trying to recover the refrigerant from a system :rofl: :ROTF: :shocked:

[Starkiller42]

That was pretty much my initial reaction, too.

[n00b 0f l337]

Haha so this recovery unit now I just think needs an oil sep. Something homemade most likely and incredilby beefy. A huge gravity sep right before condenser. Say... 1' or so tall with 1" pipe should do. Basically out the bottom, handvalve to the other suction port. Bring the input around 3" from the bottom, will trap most oil I think.

[wdrzal]

you guys will be recovering all vapor in those small systems, you just need a filter/dryer for recovery units. high pressure cut off and either a tank with a float that shuts it off when 80% full or a scale and a calulator so you can determine 80% capacity by weight(remember all refrigerants do not weigh the same) some weigh 1.5 times that of same volume of water and some weigh.5 times the same volume of water.

recovery is different than recycleing.

simpley ,some refrigerants take up a lot more space for a given volume.

[Exahertz]

Is the 80% rule based on the weight of water (water being the constant)?

[Xeon th MG Pony]

80% rule means that there is room for gass & fluid volume to expand with out it being all liquid and rupturing the cylinder via hydrulic transmission, I hope you can understand that, I know exactly what it is I just can't word it well <_<

[Exahertz]

80% rule means that there is room for gass & fluid volume to expand with out it being all liquid and rupturing the cylinder via hydrulic transmission, I hope you can understand that, I know exactly what it is I just can't word it well <_<

i get what your saying, but whats the calibration medium for their stamped number of weight? because say im filling something that weighs 20 - 50% less than the calibration medium in liquid form. once the tank was filled to 80% of its weight, it would be full of liquid. right?

[Xeon th MG Pony]

Ah I get you, yes they use the weight of water if I recall correctly, I'd have to look it up again to be sure though.

[wdrzal]

the 80% weight will change with the working fluid,80% volume will not. so a float system works well but expensive ,doubling the cost of a tank. To use the weight method you must calculate the specific gravity compared to water.the following example in in terms most use everyday.we will use a 30# recovery tank for example.

a gallon water weighs 8.33# now say you have a 30# recovery cylinder,since they have no idea what gas will be inside they stamp 30# on the tank, they also stamp the tanks empty weight. So a 30 # tank full of water will hold 3.6 gallons minus 20% = 2.88 gallons or 23.99.#say 24 pounds of water or a refrigerant that had the same specific gravity(weight).

now propane weighs 4.2# per gallon=7.14 gallons full less 20%= 5.7 gallons but that won't fit . since it hold 3.6 gallons by volume,less 20% .
now the tank full only has room for 3.6 gallons full less 20% for expansion.2.88 gallons so 2.88 X 4.2#( of propane) =12.09 pounds or half the weight of water.......

so you can legally put 24# of water or refrigerant with same specific gravity of water which is 1 in that tank. Or put 12 pounds of propane. a pound is a pound but the volume per pound changes. the specfic gravity of propane is .495 @25 c thats 100% pure or R290. propane fuel is .806@25c see the differenceand the fuel is .585 @-40 .

temperature affects specific gravity.so you want the specific gravity at standard temperature

I used these substances cause propane(pure r290) is a little less than 1/2 the weight for the same 1 gallon volume of water. r22 is heavier than water.

water and air are given the value of 1 in specific gravity of liquids and gases.

so by multiplying by the specific gravity of the liquid refrigerant the conversions are simpler. I used the above example to get the point across. in gallons and pounds and percentages.

Everyone who passed their 608 type 1 should know this. This was a rambling explaination, I tried to shorten and show the relavance with weights and volumes you use every day. If I have time I will try to find a better example of doing the conversions. you will be working with the specific gravity of the liquid refrigerants @standard temperature.

[Starkiller42]

After exhaustively searching for an affordable unit online, I've come to the conclusion that building one of these is my best option, as I already have an old extra compressor laying around.

My problem is this: if I'm not mistaken, you are supposed to use a hand valve to return the oil back into a suction valve of the compressor, correct? Well, how do you do this in a rotary compressor, with just one suction line, which is fairly high up?

Also, could someone quickly describe the process of using the hand valve? Is it along the lines of "wait a few minutes for oil to collect, open for a second, rinse and repeat" ?

Thanks in advance!

[Blaster]

really ugly recovery unit lol

[[XC] 2long4u]

Wdrzal I have a question for you. If say R134a is at 70 degrees it would have a specific pressure. So what if it was full to the top. It wouldn't produce anything over that pressure regardless of how full it was. Example: a 2liter of soda. You fill it to the top. It builds pressure until it gets to a pressure where the co2 doesn't come out of the soda any more. When you open it the pressure escapes and it fizzes. When you put the cap back on the pressure builds up again. Now if you could find a way to pressurize the bottle up to the point where it didn't release co2 then the soda would be carbonated to the last drop. So why not fill them to the top?:2cents: :horse:

[Starkiller42]

Just a guess, but some safety experts probably decided that 80% was a nice, safe number, which would make it almost impossible for a technician to overfill the unit. It just gives some legroom when working with refrigerants with different densities, so those calculations don't need to be exactly perfect. Because over-filling a container is BAD.

But if someone could answer my questions a few posts up, I'd appreciate it ;).

[Xeon th MG Pony]

because the liquid its self expands as it warms, liquid can not compress thus it simply rips the cylinder apart into nasty hyper velocity shrapnel.

get your self a charge & check cylinder, fill it half way via the sight Glass in the unit and note where it is and the temp, on a hot day look at it again, you'll notice the liquid level is now higher then it was on the cooler day. Now imagine it was filled to the top! Where will the new volume go! Refrigerant is not just a gas, it is a liquid gas mix!

[[XC] 2long4u]

So it expands more than a water based liquid? Once again if you take water and fill it to the top and set it out in the sun the PLASTIC bottle will be tight but they rarely burst.

[Xeon th MG Pony]

Refrigerant is not water though now is it ;) Try freezing it and see what happens, water expands much more when it freezes, For refrigerant it expands when warmed, for R-12 a 10degree increase raised the level by an inch or more.

[Exahertz]

So it expands more than a water based liquid? Once again if you take water and fill it to the top and set it out in the sun the PLASTIC bottle will be tight but they rarely burst.


PLASTIC bottle

Plastic expands with the heat as well + its streches more than metal.

[wdrzal]

So it expands more than a water based liquid? Once again if you take water and fill it to the top and set it out in the sun the PLASTIC bottle will be tight but they rarely burst.

@ what pressure would the water be when you put the cap on @ sea level ?

pisa??

psig??

is there a differance ? if so what???

is refrigerant different than water ? how so?

[_HL4E_HalfLife_]

is refrigerant different than water ? how so?

A compressor can compress it:D

[wdrzal]

A compressor can compress it:D

Wrong answer,:D a compressor can compress water in its vapor state(steam) just as it only compresses refrigerant in its vapor state.

if we lived on a planet where it was 150C water would be a excellant refrigerant down to 0C then antifreeze would need to be added.

but if your body functioned @150C 0C would be mighty cold.!!!!

[[XC] 2long4u]

A compressor will seize if it gets refrigerent in the liquid state. Thats why when you charge the system while adding oil, you ALWAYS charge from the high side port.

[johann]

OMG man what the hell are you talking about!

[Exahertz]

A compressor will seize if it gets refrigerent in the liquid state. Thats why when you charge the system while adding oil, you ALWAYS charge from the high side port.

whow, hold on there...

think about what your saying. your almost building a bomb in that instense. if you did that and didnt catch that F#C! up, your charging cylinder would explode!
the compressor is compressing the refrigerant on the high side and the pressure is increased. this pressure is WAY higher than refrigerant in ambient room temp conditions, thus the unit's charge would tend to backflow into the charging cylinder (this is a method used for removing some of the unit's charge as simple recovery using only certified equiptment such as recovery cylinders and HP hoses, never refill a "non-refillable" cylinder).
you want to charge on the low side whare the pressure is decreased via the suction of the compressore. and be very carefull when charging with liquid, bump it in and let it equlize a little or you could slug the compressor with pure liquid!

work safe not suicidal

cheers!

[[XC] 2long4u]

Johann. What are you talking about? A liquid can't be compressed. When you add oil to an ac system you add it to the high side port. If you put it in the low side port it can go into the compressor and break things. What do you do for a living?

[Exahertz]

are we talking about an initial charge whare the compressor isnt running and is dry of oil? or the comp has oil and your adding recovered refregerent with oil in it? thats two totaly different animals there. and in some instances your correct, however there are a few differnt ways that it can be done.

[[XC] 2long4u]

whow, hold on there...

think about what your saying. your almost building a bomb in that instense. if you did that and didnt catch that F#C! up, your charging cylinder would explode!
the compressor is compressing the refrigerant on the high side and the pressure is increased. this pressure is WAY higher than refrigerant in ambient room temp conditions, thus the unit's charge would tend to backflow into the charging cylinder (this is a method used for removing some of the unit's charge as simple recovery using only certified equiptment such as recovery cylinders and HP hoses, never refill a "non-refillable" cylinder).
you want to charge on the low side whare the pressure is decreased via the suction of the compressore. and be very carefull when charging with liquid, bump it in and let it equlize a little or you could slug the compressor with pure liquid!

cheers!



:shakes: :slapass:
Ok let me clarify. When I charge automotive ac systems the compressor is not running. I am using a recovery machine. Some recovery machines like the new robinair do not let you charge on the low side if you are injecting oil. And I'm sure on the ones that let you charge on either side, the line that has the oil in it is the high line. Theirfore if you inject oil and only open the low side valve you wouldn't be injecting oil. :yepp:


an additional charge or first charge, depends on if the system will take any refergent or not. Eg: the systems pressure is greater than the bottle pressure.

[wdrzal]

charging cylinders also know as factory jugs of refrigerant have a check valve,refrigerant can only flow out.

Your high side gauge,manifold and hoses MUST be rated for maximum high side pressure of the system you are working on.

[johann]

Johann. What are you talking about? A liquid can't be compressed. When you add oil to an ac system you add it to the high side port. If you put it in the low side port it can go into the compressor and break things. What do you do for a living?

What I do for a living has nothing to do with this subject.

Do you think because you work on car AC's that it make you better than others or give you more knowledge than others when it comes to building Computer phase change units?

Honestly I havnt read 1 post from you that is atall relevant to PC phase building. Why dont you start a Car ac forum? That way you will be able to give helpfull input.

All you do is spam crap

[Xeon th MG Pony]

and car ACs are very different, the compressors have nearly no oil sump so the charge is allot smaller and flows through the entire system continually.

In these systems there is an oil sump. I suggest you learn about the basic differences, what will work in a car will not work for here, hermetic systems are not as forgiving to moisture, air, or dirt as a car would be.

[[XC] 2long4u]

Johann:
No I don't think I'm better than anyone. I just have been dealing with automotive ac for about 8 years now. I have a bunch to learn about the other side of the field. And as far as what I have to offer may be a little different. Sometimes people need a different approach to something. For instance autos don't use captube, they can't, they need a metering device to regulate temp so they don't freeze up. So maybe somebody could use an expansion valve to regulate load. And I was just wondering what you do? :shrug: :buddies:


Xeon:You said the compressors have nearly no oil sump... Well that depends on what compressor. Example:York- they have an independent sump which makes them Ideal for an air compressor on a vehicle, (onboard air for 4-wheeling). And I don't know what you are talking about a smaller charge. Most vehicles take atleast 2lbs. :up:

[Starkiller42]

After exhaustively searching for an affordable unit online, I've come to the conclusion that building one of these is my best option, as I already have an old extra compressor laying around.

My problem is this: if I'm not mistaken, you are supposed to use a hand valve to return the oil back into a suction valve of the compressor, correct? Well, how do you do this in a rotary compressor, with just one suction line, which is fairly high up?

Also, could someone quickly describe the process of using the hand valve? Is it along the lines of "wait a few minutes for oil to collect, open for a second, rinse and repeat" ?

Thanks in advance!

Can my questions get a little love? They're quiet lonely right now, but I think with a little bit of attention they could help a lot of people out ;).

[[XC] 2long4u]

My problem is this: if I'm not mistaken, you are supposed to use a hand valve to return the oil back into a suction valve of the compressor, correct? Well, how do you do this in a rotary compressor, with just one suction line, which is fairly high up?

The hand valve is for a cascade where the temps are so low that the oil will freeze in the captube. The valve returns oil to the compressure fron an oil seperator. They normally are not used in ss units.

Does anybody need a York compressor I have 7 of them. I'll give them away for the cost of shipping.
The York has a seperate resevoir for the oil. Thats why you can use them as a air compressor without an oil feeder.

[Xeon th MG Pony]

Yorks ya, most them larger ones have a good sump, but your usual swash plate style compressor not so large. Oil is dense, so 2 pounds can be accomplished with little volume! must be one hell of a swash compy to use 2 pounds of oil though, thats huge, Frankly I've never seen one that big even on a comercial boat!

[Starkiller42]

Thanks 2long, but a few of the fellas were talking about using them in conjunction with an oil sep in a "proper" recovery unit...so I was wondering how I might tie that in :D.

[[XC] 2long4u]

On a recovery unit the oil return doesn't go back to the compressor it drains into an open bottle and is discarded. Imho a York would be the best for a recovery pump as it has its own lubrication just like a vacuum pump. The only thing is its drivin by a belt.

[DetroitAC]

A compressor will seize if it gets refrigerent in the liquid state. Thats why when you charge the system while adding oil, you ALWAYS charge from the high side port.

2long, I think you're a victim of the typical misinformation that exists within automotive AC. The problem is that many technicians are just not the sharpest knife in the drawer, so instructions must be written for them. You may be quite a sharp guy, I don't know you, I'm just saying that many are not.

1st Point: compressors pump liquid
A refrigeration system in the off state has liquid generally at the coldest spots if gravity allows. If the components and pipes are all at the same temperatures, the liquid is in the low spots, but it's very hard to know where it is unless you know the "history" of the vehicle (when it was operating last, how have the temperatures changed since then).

A good example of this is the following: You drive you car to and from work on a friday (AC on), and then park it friday night and you don't start it again until 10:00 on a sunny saturday morning => the compressor is likely FULL of liquid refrigerant and you will get a heavy slug (comp pumps liquid) when it engages. Why: on friday night the condenser, evap and lines cooled down quickly after you parked, but the engine took longer to cool down (big thermal inertia), the liquid moved to the evap and condenser (thermosyphon or heat pipe type movement). On saturday morning the sun warmed up the car interior and the condenser, liquid moved to the cold spot which is the compressor (bolted to the engine, which is still cool). Voila, the compressor is full of liquid.

The good news is that every compressor maker is well aware of this and tests the snot out of the compressors to withstand this. I used to work at the company that makes Ford compressors (Visteon). There would be a compressor durability stand in the lab running at all times slugging 115cc scrolls at 6000 RPM over and over. Sounded like it was pumping marbles, but they would survive the test.

Car makers also have first engagement algorithms that pulse the clutch so that you can't hear the slug over the sound of the engine starter motor. Some cars slug so badly that you will never be able to hide it, some curiously don't seem to slug :shrug:

2nd point: you can charge to the low side port
I don't think I have ever charged a vehicle through the hide side port. Some OEM specifications for engineering tests specify charging through the low side, some don't specify. In my opinion, if the system is off it doesn't matter which side you charge into (see above argument, the liquid is going to go wherever it wants to anyway). If the system is running, you can only charge into the low side. We charge into the low side for engineering work because we frequently want to tweak the charge to get exactly the subcool we want (i.e. add only 5g ). This comes back to what I said about not so bright technicians. You have to be very careful and know what you're doing to charge to the low side. You have to do it slowly. If you tell a new or bad technician to open the valve to the low side to add some more charge he may throw it wide open, sending a huge slug of liquid into the pump. So procedures must be carefully written so that ANY technicain can follow them and get the job done without grenading the compressor.

There are devices for commercial refrigeration that attach to the charging hose to make sure liquid flashes off when charging to the low side, there is nothing like this for automotive that I know of.

When I add oil to a running system, I add it to the low side in small doses and slowly. It's faster than shutting the system down, recovering, evacuating and letting the vacuum pull the oil in. I just use an injector syringe, pull the suction pressure down pretty low (so it's easier), and squirt, done!

[DetroitAC]

I'm a typing mood (and avoiding mowing the lawn), so let's talk about recovery units.

Oil return:
Let's divide commercial units into two categories, oil-free compressor and hermetic compressor.

The oil-free automotive units use and oil separator to return the oil to a port which will drain into a small bottle (I think 2long mentioned this). The technician can then look at how much oil was pulled out and add the same amount new oil back to the system (or if a cheap shop, dump the dirty oil back in :shakes: ). Oil-free commercial recovery units, are pretty much what the OP has shown. Just a compressor and condenser, but there are safety controls.

Hermetic compressor models, oil return gets a bit complicated. You know that some oil will be pulled out from the system, and you know that the compressor will slowly lose it's own oil. Both must be dealt with. We have an old Robinair unit at work that is like this. There is a crude oil separator (empty can) on the incoming line with a heater in it. If the sytem pulls in liquid, it will evaporate in this can before going into the compressor suction. This can has a drain valve to an external bottle. The compressor has a proper oil separator after it with a reservoir of oil, oil is returned to the compressor suction by a solenoid valve with a capillary to control the flow rate. I think this operates on a timer (that's how I'd do it anyway), so many minutes of runtime, open the solenoid valve for so many seconds. The last seperator has some real efficiency (less than 100%), so the unit must be sending some oil into the recovery cylinder, thus the need for a reservoir.

I've known guys that use those Yorks for air compressors. You can do that for quite a while without adding oil, since you use it infrequently, but you would have to occasionally (few years maybe) fill the sump back up with oil.

[star882]

There would be a compressor durability stand in the lab running at all times slugging 115cc scrolls at 6000 RPM over and over. Sounded like it was pumping marbles, but they would survive the test.
The scrolls are supposed to be more tolerant of liquid. How well do the recips tolerate it?
But based on how a scroll compressor is constructed, wouldn't liquid just fall to the bottom and mix with the oil? I think bearing wear might be more of a problem.

BTW, I think most modern scroll compressors operate at 3600RPM.

[DetroitAC]

Automotive scrolls Star, RPM is determined by the driver's right foot. All automotive compressors (wobbleplate piston,swashplate piston,scroll,vane) are designed and developed for liquid slugging durability (they have to be, my point was that it always happens in vehicles).

[Starkiller42]

Thanks for the interesting and informative read, DetroitAC! Post 50 especially was useful in better understanding a 'proper' recovery system.

[_HL4E_HalfLife_]

But based on how a scroll compressor is constructed, wouldn't liquid just fall to the bottom and mix with the oil? I think bearing wear might be more of a problem.

BTW, I think most modern scroll compressors operate at 3600RPM.

You are correct, the liquid would just drop to the bottom of the compressor shell and return to a vapor form.

I've hacked open close to a dozen compressors which are mostly recip's but a few of them are rotarys and 1 is the huge scroll i posted vids on a while back and the way they are designed its next to impossibile for a recip to slug liquid unless the laws of gravity don't exist inside a compressor shell for some reason:confused: :confused:. The only way a recip will slug liquid is if the entire compressor shell was completely filled up with liquid refrigerant which is impossibile unless a total moron was charging the system and massively overcharged it.

[Xeon th MG Pony]

never under estimate the power of stupid people! especially in large groups!

[[XC] 2long4u]

Detroitac: Well said. I do charge from the low side for a partial charge. But anybody I've ever worked for never had a dye/oil injector. I've always used the high side or added oil strait in a line. My point was oil going into a compressor is very different than refregerent going into a compressor. Granted it probably won't cause a failure, I just wouldnt want to be the one that breaks it.:up: :up: