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What car is used as a buffer when moving flammable materials?

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What car is used as a buffer when moving flammable materials?
Posted by DAVID FORTNEY on Wednesday, September 16, 2020 11:08 AM

Is it a certain type of car? Is it loaded. How many buffer cars are used. 

Btw this for today's era.

Dave

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  • From: Mpls/St.Paul
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Posted by wjstix on Wednesday, September 16, 2020 11:21 AM

The solid/unit tank car trains of oil I see coming from North Dakota use covered hoppers specifically designated for buffer service by the railroad on each end - so behind the lead engine(s), and in front of any trailing or pushing engines on the rear. My understanding is they're usually filled with rock to provide weight / ballast.

Model RR example:

https://www.scaletrains.com/product/ho-gatc-4566cf-airslide-covered-hopper-bnsf-buffer-service/

Stix
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  • From: Canada
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Posted by cv_acr on Wednesday, September 16, 2020 12:02 PM

Any car that is NOT:

- loaded with dangerous goods
- having open flame heater(s)
- shiftable open top load.

For moving hazardous good in general freights, dangerous cars cannot be next to any of the above, must be a certain distance from engines (if length allows), and there are further restrictions against certain dangerous commodities being beside each other (like explosives and poison gas etc.)

Cover/buffer in regular trains is just done with the other cars in the train and placing dangerous cars in the right position.

For unit trains, US rules require adding a buffer car, which can be anything other than the above, but rather than fish out a single car that may or may not be going to roughly the same place, dedicated buffer cars (usually retired hoppers, sometimes loaded with sand for extra ballast) are used for this service. (Note buffers for unit trains aren't required in Canada, but any unit train that runs through to/from the US will have one.)

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Posted by jeffhergert on Wednesday, September 16, 2020 2:56 PM

Our train lists use a hazardous word endorsement for the different groups of materials.  One of the words used is "dangerous" so I don't like lumping all restricted materials as dangerous.

Here is a instructions, including a placement in train chart from the AAR.  

https://www.aar.org/wp-content/uploads/2017/12/AAR-US-Hazmat-Instructions-Rail-BOE.pdf

Scroll down to page 34 or 35, figure 11.  Note that there is also a chart for switching hazardous materials.

You'll note that loaded tank cars have the most restrictions.  Other cars, even with a load from the same group not so much.  There are even some placards that have no restrictions.  They can go anywhere and even be used as a buffer car.

Jeff

  • Member since
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  • From: Omaha, NE
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Posted by dehusman on Wednesday, September 16, 2020 7:09 PM

DAVID FORTNEY
Is it a certain type of car?

No.  It can be any type of car, loaded or empty, EXCEPT that the cover cars can't be loaded placarded tank cars (other than combustible) AND the car next to the flammable TANK car can't be any car placarded radioactive, poision inhalation hazard or explosives A, a shiftable load or a mechanical reefer.

 How many buffer cars are used.  Btw this for today's era.

A placarded loaded tank car must not be closer than the 6th car from the engines or occupied car (5 cars of cover) UNLESS "train length does not permit" (which means that there are no other cars in the train that can be used as cover) then the loaded placarded tank car must not be closer than the second car  from engine or occupied car (one car of cover).

If its a unit train of flammable liquid, then "train length does not permit" there to be 5 cars of cover, so they add a dedicated cover car, which could be any car, but typicall is a covered hopper loaded with sand.  A covered hopper because its enclosed and easy to load with sand which is inert and cheap.  

There is no Federal regulatory requirement that the cover car be loaded or empty or what type of car it is.  The railroads use a loaded car for train handling purposes (having an empty car next to the engine with a solid block of loads behind it is a derailment risk). 

If its a regular train then it will generally be 5 cars of whatever is handy in the train that's not another loaded placarded tank or a prohibited car.

 

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by OldEngineman on Wednesday, September 16, 2020 9:57 PM

I had a Conrail "HAZ" train once in the late 80's, 40 cars of sulfuric acid and 2 SD40's. It came with a covered hopper between the engine and the tank cars, I don't know if it was loaded or empty.

One other thing that train had -- a "surefire" kicker -- touch the train air and... BANG! I ran that one from Port Jervis (on the NY/PA line) to Oak Island (NJ) without using the train brakes AT ALL. Not once. Was on the edge of the seat a couple of times. That was a good story...!

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