I asume PVC pellets are non-toxic…But when we order cars we can not use grain cars for our shipments and we can not use cars from the plastic Pellet pool.
#1…Product contamination…plastics recievers want absolutely no contamination that will foul machines and create wasted parts
#2…Grain users also do not want plastic mixed in with grain be it for flour or cattle feed
#3… Plastics are light weight and utilize high cubic capy cars to maximize the load (5000 plus cubic ft to reach 263000 or 286000 gross wt vs a 4750 cube car that will weight out when loaded with grain)
#4 …Unloading systems with plastics are normally some type of pressure aid while grain typically uses simple gravity drop unloading
#5…Plastic producers typically make grades of plastic on a campaign basis and there are many grades of plastic, too many to economically build silos to hold all of them seperately. The most effective way to handle this is to have large private fleets and store the product in cars which are held in SIT tracks (Storage in Transit). Once recievers order products, the proper grade is shipped from the SIT storage. This allows producers to ensure cars with proper size and unloading equipment and clean dedicated cars.
A number of reasons could be possible. First of all a railroad has to assure shippers it has adequate cars to obtain the business hence dedicated cars. Secondly the FDA and agricultural rules and regulations require a certain cleanliness and cleaning the inside is a bear. Thirdly most cars have a coating on the inside which probably does not have FDA approval to touch food surfaces. Lastly are the cars owned by the railroad or a private shipper? Concern for liability may retsrict usage since the owner doesn’t want to get sued.
There must be a way to come up with a car that can handle both.
If I can eat my oatmeal in my tupperware container and eat my food with my plastic fork…
There are many food grade coatings avalible incluiding teflon that would allow gravity unloading of grain and plastic pellets
The idea of SIT could work for grain and eliminate huge central grain terminals
It’s not the pellets nor the grain, it’s the fines of both items. You may indeed eat your food with a plastic fork and keep it in a tupperware container but I guarantee you neither the fork nor the tupperware are shedding fines into your food.
Even with flushing and coating you are going to get fines in the mix and food fines in plastic will play hob with plastic extrudate quality while plastic fines in your food will play hob with your digestive tract.
'cuz plastic pellets don’t taste good in my Corn Flakes!!! [swg]
OK but…Does that mean that Bulkamatic Trucks have to adhear the same standerds?
Yes, they do! To paraphrase the old Lynyrd Skynyrd song, “Mr.Saturday Night Special”, with regard to trucks or railcars that are used to haul plastic pellets,“They ain’t good fer nothin else!” The pellets tend to remain in the car or truck no matter how hard one tries to clean 'em! You can’t even ship different classes of plastic in a truck or car, let alone food in a car that has had ,say PP in it, turn around and then ship PVC! The PVC will be contaminated, or to use the polite term, “compromised”.
And sometimes compromise isn’t the answer! [:D]
Last time I checked PVC, while not a deadly poison, is not something you want to eat or have livestock eat.
Also, all the above contamination arguments apply…
LC
Aren’t they different cars as well? I think most plastic pellet cars do not rely on gravity for unloading but on pressure differentials. I always assumed grain cars just dumped the load using gravity but may be incorrect.
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Not exactly on topic – but “back in the day” railroads such as the Rock Island would take stockcars, sheath the interior with plywood to close up the slats, and use them as grain cars during the fall grain rushes! Yumm. This makes me wonder if the goal is to protect the plastic from the grain, not the grain from the plastic.
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More on topic, note that many of the ACF center-flo type cars used for plastic pellets have warnings on the side about how not to clean the car, that someone inside the car has to wear special shoe protectors, etc. There are good reasons to dedicate such cars to a single type of service, so the car rarely if ever has to be cleaned.
When I was younger I lived near a local company that got plastic pellets in ACF cars (El Rexene) that they used to make clear plastic bags – I think the kind that dry cleaners use (In fact the factory had been a dry cleaning facility at one time) and the heavy duty bags that at the time were popular for lawn waste. Obviously the business would prefer to just use the pellets and not have to clean any kind of dust from them – and grain dust is potentially explosive to boot.
From time to time handfuls of the plastic pellets would spill at the unloading site (a metal box with special hoses), which was across the street from the factory itself (model railroaders, note an industry that can be modeled without a building). The pellets were about the size of aspirin tablets and translucent but not clear, and completely clean.
Dave Nelson
Mr. Nelson has the answer…
The idea is to protect the plastic from any contaminate.
Grain, on the other hand, is pretty filthy, in both the car and the ships/barges it is hauled in.
Not your big clods of dirt filthy, but still contains enough actual dirt and other containments (bugs) that it is washed, process dried, then washed or cleaned again before it ever sees a grist mill.
Plastic goes from the hopper directly to the process, extruder or “oven” depending on the product being made.
PVC powder cars are pretty much dedicated to that service, if you get close enough to one you can see the sticker on the sill of the car warning about the carcinogen hazard and the dust hazard…they are grounded before unloading because of the static charge that builds up, and most of the powder cars have vibrator brackets on the undersides, along with warnings stickers noting “Do not hammer on side of car, will contaminate contents” because you can break the Teflon lining off if you vibrate or beat the car sides.
The clean out guys wear slippers, made from a nylon and cotton blend, when they enter the car, to prevent scratching the lining.
They don’t sweep the car, but used a compressed air hose and a vacuum set up to clear any residue powder.
The canister filters get left on the ends of the cars a lot…they are about the size of a 5 gallon drum of clothes washing soap.
Pretty big vacuum!
Standard plastic hoppers carry everything from Durlin,(sp?) (engineering plastic, the “slick” stuff) to pellets of PVC, along with just about any other plastic you can think of, except styrene, which is shipped in liquid form in tank cars.
The styrene has a shelf life of a month or so in the tank car, so they are sent as blocks every chance we can.
Ed
All this makes me think twice before I eat my toast in the morning[xx(]
And why I should have switched jobs, before I did!!
Ed Blysard and Dave Nelson havethe problem dead on.
THE issue is called product cross contamination! Fuzzybroken has the right idea.
To illsustrate, here in SEk there is not a local readily available supply of sand, it must be brought in from other places; generally, that origin is Tulsa or Wichita, both have the Arkansas River for a resource. Truckers and railroads both try for loads both ways. As was pointed out by another post, hopper cars can be loaded with any material that can be gravity unloaded. A concrete company in the area here has its sand trucked from Wichita, and those trucks haul soybeans and wheat as a backhaul. At some point the drivers failed to properly clean the trucks of bean residue, and it contaminated the sand on the next leg. THat sand was used to make concrete for a pretty sizable slab, and the heat of the curing concrete caused the beans to germinate, the folks that were building on the slab were not happy with the soybean sprouts coming out of their concrete slab. And similarly, ten loads of sand railed into the area were also contaminated when the cars were not properly cleaned adfter delivery of their soybean loads. Cross contamination can get really expensive; so thatr is why products are kept apart in transit.
Once I was preparing to set up a MP airslide for bulk flour loading. This car last hauled sugar and on the side of the car was stenciled sugar loading only. After the last sugar load, the car was not washed and suitable for flour loading. Upon inspecting the inside of the car it was rejected. Sending sugar cars to a flour mill, hmmm.
I work for people that are [D)] enough to accept cars that aren’t right for the product they wi***o ship! The consequences can be expen$ive, if not caught. To top it all, if we load an incorrect car, we get the blame![B)] So, 'tis better to send the cars back and have them cry about late shipments! CN, for all its faults, does monitor cars so that you really have to “outwit” their order system to get the wrong car for what you ship. Then there are carriers that could care less. I will not name any names. But they do not have a name, as such!