Atmos Bellows Work?

[Tony Wells]

OK.....so far so good. So, is there a specified amount of EC to have contained? If so, how do you plan on keeping such a volatile substance contained to prevent evaporation loss? Keeping it (along with the entire bellows assembly) below it's vaporization temperature? And at the same time, solder closed the service port? I know at room temperature, soldering hollow objects can be tricky. For example, something as simple as a brass carburetor float tends to suck the solder in as the air inside cools enough to change the internal pressure and draw the solder in before it solidifies. The only trick I know of for that is to keep the entire float near or slightly above the solder melting point. Or is there a sealant of some sort other than soft solder than can be used?

 

[tq60]

The temperature control was the start of this.

There is a u tube video of someone charging one and with the boil point at 50 degrees he used clamps and freezer with bed of ice.

Sloppy and risky but worked.

Our goal was to build something that both would clamp it closed as well as maintain the temperature below the 50 long enough to do the work.

The clamp bowl with the pressure covers stored on the bottom weighs in at about 7 pounds.

So assembling it and tossing it in the freezer overnight should allow it to stay real cold plenty long enough to fill plug and solder.

The volume suggested on the video is 5 ml liquid so that is starting point.

The factory crimped and soldered which is not servicable so our plan is to use copper wire of #14 or #12 and with the high speed hand piece make a very small degree taper just like taper pins have and fit that to the port so pressing it into the port alone should seal it then solder in place.

Have not tested hold time yet but assuming it takes just a few minutes to do we should have plenty of time.

The port is somewhat elevated and on opposite side of the bellows.

The 5 ml is a small amount that should be resting on the bottom surface which is against the cold steel.

This allows it to be serviced if the 5 ml amount is not correct.

Contacted FDA regarding controls of EC and they only are concerned with medical use and could care less regarding industrial uses such as this so no concerns regarding possesion.

The problem is the usual sources in the quantity that one needs are purely medical and are only licensed to sell as medical...

Working a few different angles to see how we can get some...

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[Tony Wells]

OK then next, how do you test/verify that the temperature/physical expansion curve is correct? Is there a specification for that? I would have to assume so.

 

[pebbleworm]

For the ethylene chloride, you can get a small quantity on eBay:
http://www.ebay.com/itm/1-2-Dichloroethane-99-0-100ml-/272179211695?_trksid=p2141725.m3641.l6368

 

[tq60]

The stuff on ebay is something different.

Only thing that shows up there is empty containers.

Maybe folks buy them then fill with something else to sell to dope heads.

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[tq60]

OK then next, how do you test/verify that the temperature/physical expansion curve is correct? Is there a specification for that? I would have to assume so.

Not sure what you mean here.

If we were using a different gas maybe but it is listed as Ethyl chloride gas in multiple places so we will use that.

We do test the bellows by freezing it then assembling it into its housing.

Then observe that it reacts to temperature change.



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[Tony Wells]

I'm just questioning how much expansion you will see when the assembly returns to room temperature, and an equilibrium forms between the liquid space and vapor space. At some point, it will reach the saturated vapor pressure in the bellows unless there is an incorrect amount of EC present. Of course, this exact saturation point will vary with temperature, as will the pressure within the bellows. But then, since they are bellows, they can expand or contact to keep the volume needed to maintain that equilibrium. So, basically I guess I want to know if there are specific dimensions (length primarily, or course) for a given temperature already worked out to verify that you have the correct amount of EC inside? And would there be several temperatures at which this dimension would be checked?

It seems that the volume for a bellows set would be basically fixed as a standard with it compressed, and if "someone" says 50 cc (ml) is the correct amount of EC (at what temp?) then this information has been verified or specified by some precision means, perhaps at the OEM level.

 

[tq60]

OEM...?

You are funny guy....

They do not give out much info so it is just what yiu can find.

With the bellows in its housing it has a stiff spring to place counter pressure against the gas.

Reason for making the port servicable is if the volume is not correct we can add or subtract some as needed.

Atmos man has a great amount of information including testing the operation and it seems they operate over a range of volumes as he indicates some with partial loss still work but at a lesser range.if at room temperature it is fully expanded an placing an ice cube in the cavity causes it to colapse then we could call it good.

We could take one from aa good unit and do some specific temperature and measurements if need as the volume of gas may matter a bit but if we recall from basic physics the boiling point is based on pressure and temperature and not volume so as long as there remains some liquid the boiling point would increase as temperature rises and increase pressure against the spring.



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[Tony Wells]

Forgive my questions if they seem to make me dense. I'm just trying to see how these things work. You are correct that the bp does not change with volume. However, the pressure in a closed vessel will change as the temperature changes; but in this case the volume is allowed to change along with the temperature and the bp will stay the same, only varying by any restriction of movement that may keep the volume from changing proportionately with that temperature. I didn't know about the spring either. This is why I asked if there was a temperature/expansion curve that should be checked.

To show what little I know, I don't even know the overall function of this particular component. If you don't mind, give me a brief rundown on the basics. Just what does this bellows do? I guess deep down I am also wondering if it MUST be EC or if another, perhaps easier to source substance could be used.

 

[Superburban]

I'm with Tony, still trying to grasp the whole concept. I'm assuming that the bellows winds the clock spring. But do not see how there would be enough temp/ and or barometric pressure changes over a few days period that the clock would need to keep the clock spring wound. I have one of those fancy clocks that has time/ indoor & outdoor temp, and in the winter, the indoor temp hardly ever changes, and then it is only one degree.