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Near as I can tell, Overland OMI imported 3 different versions on tank cars in this catagory. Simplified, one with high walkways, one without, and one with heat shields covering the tanks on each side of center.  How many of each of these were imported, were any of them factory painted, etc?

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According to Wiki, By 1845, Michael Faraday had managed to liquefy most gases then known to exist. Six gases, however, resisted every attempt at liquefaction[11] and were known at the time as "permanent gases". They were oxygen, hydrogen, nitrogen, carbon monoxide, methane, and nitric oxide.

Nitrogen was first liquefied at the Jagiellonian University on 15 April 1883 by Polish physicists, Zygmunt Wróblewski and Karol Olszewski.

So the gases have been around for a long time. When they were first put in tank car built specifically for that purpose, maybe in the 1920's?

OSCALETRAINS,

Just some additional sidebar chatter. The OMI argon cars were probably prototype in the 1960s. I don't know how long they were operated before final retirement or what type of tank car or from what manufacturer followed them. I first saw the car with sun screens as a wooden kit at Caboose Hobbies when their store was located on 15th Street in downtown Denver, Colorado. I believe the kit was made by Scale Craft. OMI #0738 is my favorite. How can you not like this model, encrusted with ladders, walkways, control valves, refrigeration equipment, and the like. While obsolete for the current prototype era, given the great tank cars that Pecos River Brass gave us around 2000-02, and the Atlas O 25,500 gallon Trinity tank cars now in production, one could probably slip one or two of these into line without much complaint from a timeline purist. Conversely, I suspect that the sun-shade equipped model probably wouldn't fly much beyond 1980-1985.

 

I have seen the OMI 0738 walkways version in O scale painted 3 different ways, black/liquid air, white/Linde and blue and white some Canadian company logo AL. In real life photos also painted black and white/NCG.

The heat shield version in O scale I have only seen painted in white/Linde but have seen real life photos of a black/liquid air and an orange and white/Airco.

The other "standard" version in O Scale seems to all be white/Linde but real life photos show it in any number of schemes, white/Big 3, orange and white/Airco, blue and white/AL, black/Air Products.

 

I remember reading a scratchbuilding article about these cars in an old MR way back when.  I think it was a black/Air Products version with metal plates attached to the tank sides for lettering.

The diametrical rings on the outside of the tank shell are required to prevent the implosion(collapse) of the outer tank as deep vacuum is pulled in the open volume between the outer tank interior surface and the outer surface of the on the tank interior. The interior tank contains the liquefied gas in this case Oxygen. This tank is cradle supported from the outer tank interior surface, the outer tank is the structural tank of this tank car that is subject to all the trainline forces and resultant strains and stresses. The deep vacuum is not a complete vacuum(-14.7 psi or -29.92 inches Hg) it acts an insulator to prevent heat transfer between the two tanks.These tank cars also have a piping system for the vacuum system and loading/unloading the liquefied gas pressure gauges and valves are in an cabinet on the outer tank exterior surface. Within the rail industry these car typically are called LOX cars, the cars that I was involved with in the past were built in 1969.

Last edited by John Ochab

That is pretty cool idea with the tank within a tank and vacuum in between for insulation.  This vacuum insulation principle is the same idea that the Yeti brand stainless steel cups and thermoses use to keep their contents warm or cold - just not a complete tank in true sense as the lid has to take care of that portion of the "tank" for insulating the contents.  The rest of the cup / thermos is just an outer and inner "tank" separated by a sealed vacuum.

Here is a Mythbusters vid of vacuum collapsing a tank car:

https://youtu.be/T9bpUfWy8Wg

European rail tank car vacuum implosion demonstration:

https://youtu.be/Zz95_VvTxZM

These tank car implosions commonly occurred when the car is filled with steam for cleaning and then sealed without removing "all" the steam, even if the steam pressure inside tank reads is 0 PSIG when the valve is closed.  As the car sits, the steam condenses (especially in cold weather) and now the lack of any other gas/air inside the large tank causes a vacuum to form inside the car and it collapses as the car was generally designed to handle pressure from the inside the tank and not from outside the tank.  Most modern tank cars have vacuum relief valves to prevent this from happening but if those relief valves are overridden, then vacuum implosions are possible.

Scott K.

Austin, TX

oscaletrains posted:

I have seen the OMI 0738 walkways version in O scale painted 3 different ways, black/liquid air, white/Linde and blue and white some Canadian company logo AL. In real life photos also painted black and white/NCG.

The heat shield version in O scale I have only seen painted in white/Linde but have seen real life photos of a black/liquid air and an orange and white/Airco.

The other "standard" version in O Scale seems to all be white/Linde but real life photos show it in any number of schemes, white/Big 3, orange and white/Airco, blue and white/AL, black/Air Products.

 

I remember reading a scratchbuilding article about these cars in an old MR way back when.  I think it was a black/Air Products version with metal plates attached to the tank sides for lettering.

In one of the freight car publications (Robert Wayner perhaps) there was a picture of an Air Products tank car with outside concentric rings.   It looked to be sixties-ish and judging by the brick APCI building it was possibly in Emmaus PA on the Reading.

OSCALETRAINS

More side-bar chatter:  I think I have half a loaf to the above question.  As I remember, all three classes of cars OMI #0738, 0739 (sunshades), and 0740 (no sunshades), came from the importer painted or unpainted. #0738 was available as Canadian Air (Black) or Linde Air (white). #0739 and #0740 were only available from the importer as Linde Air. If there was a third paint scheme for #0738, I haven't seen it. All unpainted cars were supplied, as far as I know, with the proper decals reflecting the the factory painted models. As for exact numbers in each car class and breakdowns of painted, and unpainted numbers of models, I would contact Overland directly. They may have production archives that provide the numerical data on units produced. Good luck!

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OGR Publishing, Inc., 1310 Eastside Centre Ct, Ste 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

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