I am watching “Unwrapped” on the Food Network. They had a segment about making Tositos at the Frito Lay plant near Bakersfield, CA. In it they were talking about the corn arriving by rail and showed a TILX 5700 series hopper, which do go to that plant. However, the corn they showed was whole kernels. Has anyone ever heard of shipping corn kernels in a pressure assisted covered hopper? The plant also receives regular covered hoppers (usually FCTX) and PressureAide hoppers.
I think I may have seen this program (or a similar one) back in the days when we watched “Unwrapped”. I certainly wouldn’t put too much stock in that little tidbit, particularly when you know that the correct cars for corn are used in the plant. Did they mention flour or starch (both carried in PD or PressureAide cars) as being among the ingredients?
I doubt that something like corn would work in a PD car, simply because it wouldn’t “fluidize” like flour, starch, or other of he usual loads carried in such a car. Nor would they unload the corn as quickly as a standard gravity-discharge car could, I also suspect that they wouldn’t want to show the corn-unloading area, which for however brief a time would expose the commodity to open air and contaminants. Ever seen the roof area of some grain cars, with the rotted corn around the hatches, possibly with small plants growing out of it? Probably perfectly harmless in the chain of corn-chip production, but I certainly wouldn’t want to suggest anything in a TV show about food that people eat without giving a thought to such things.
Gentlemen,
Could you explain, or provide a link to explain, how a pressure assisted hopper or PD car works? This could help me understand something I used to routinely see 45-50 years ago. Any help here would really be appreciated.
AgentKid
http://www.patentstorm.us/patents/6237505.html
You get annoying little pop-up ads if you mouse over the words double-underlined in red, so avoid that. I haven’t examined any of the carbuilder resources given here, but pretty much every modern PD car is represented.
Thank you Carl. Unfortunately the real question I had was only addressed by part of one sentence: “when the car body is pressurized during unloading.” I have wondered for a long time how is that done? Is it done with compressed air provided by the unloading facility or is it train air? By the way, even the double underlined words in the “Other References” section don’t link with the manufacturer’s mentioned, but link to other things entirely.
Even though it is not related to the original question posed by this thread I will bring up why I’m asking. In the last two years my father was ill with ALS, we discussed a lot of railroad things, and one was how we got our drinking water at Irricana.
The Monday mixed brought a water tank car from Calgary and part of it’s stop involved bringing a hose from the tank car to a water tank that stood in what was originally designated the heated freight room. This normally worked fine but I could remember odd things happening from time to time. I started by asking him how do you keep the water flowing when it is 20 degrees below zero?
My Dad said that the tank car was set up so it was pressurized by the train air as it went down the track, as water under pressure would not freeze. The tank car was filled overnight on Sunday at Alyth, and then valves were turned on the dome on top of the car and at one end, and the car would be pressurized.
This worked well in the winter, but in summer when the loading crew was less conscientious they would forget to turn the appropriate valves, and the car couldn’t be unloaded when they got to our station. Then the train would just stand there for a some time while the pressure was being built up from the brake line, I guess.
Pressurized water will freeze. Figure 3.4 in Fundamentals of Thermodynamics, 5th Edition by Sonntag, Borgnakke, and Van Wylen (ISBN 0-471-18361-X) shows that increasing the pressure of water will lower the fusion/melting temperature. It could be the the pressure was high enough that the temperature was or above the fusion temperature. Compressing a gas will at heat to it, so the air could have added heat to the water. However, it seems unlikely that the pressure would have been high enough or the air added enough heat to keep the water from freezing. Could it have been steam they added to the tankcar?
How long did it take the train to get there? It might actually be that the tank was insulated and that combined with the mass of the water kept it from freezing in the time it took the train to arrive at the station. It sounds like the pressurization was just to help unload it.
Here is some more information about pressure assisted hoppers.
http://www.americanrailcar.com/pdf/mfg/HO-Pressureaide-brochure.pdf
Carl, the ingredients for Tostitos are whole white corn, vegetable oil, and salt. Also, the PressureAide hoppers are leased to Cereal Food Processors, so I suspect they bring in flour for pretzels, cookies, or something else.
So how many others would have done the double-take at the wrong covered hopper being used in the TV segment?
Kid, the PD cars are unloaded with air from the industry–one would hate to have to keep a locomotive attached for the unloading process! The pressure is generally much lower than a brake pipe would provide–PD cars unload with anywhere from 5 to 30 psi.
I, too, suspect that it was steam, not air, added to the tank car. An ordinary tank car would test at 60-100 pounds–roughly what could be put in from a trainline–but I suspect that any car used for company water service would not be up to those standards. Just a hunch. If the car had heater coils (I still don’t always know how to detect that!) and insulation, it would have been better at keeping the water liquid.
First off, when I read that line I really had a good laugh. 45 years after we moved out of the station, every once in a while my mother still brings up some crazy thing that happened with OCS (On Company Service) The combination of trying to reuse assets coupled with buying new items in enormous bulk produced some amusing results looking back half a century, but it was mighty annoying at the time.
I want to thank Carl and ericsp for the additional information. I will answer most of the questions asked in the order they came up.
To answer the question of how long it took for the train to get to Irricana, the car was loaded sometime overnight between Sunday and Monday and got to Irricana about 11:30 AM - noon. But ours was not the only station to receive water. This mixed train served in an area that has historically always had issues with the local drinking water. Modern science has been able to deal with the palatability and purification issues, but the lack of water still precipitated a political flap just a few years ago.
If we all turn to our July 2006 TRAINS Magazine pp 62-63, or purchase the downloadable pdf, Grains and Railroads, from the TRAINS store, I will explain the working of a typical CPR mixed train. It left Calgary on Monday EB on the Strathmore Sub. to Langdon, then went north to Irricana and on to East Coulee (not shown, just southeast of Drunheller). Tuesday, it went from East Coulee, south on the Rosemary Sub. to Rosemary, with a side trip to Gem, then west on the Bassano Sub. to Bassano. Wednesday, it made a round trip to Scandia via the Brooks and Cassils Sub’s. And on Thursday, it left Bassano going north, then west on the Irrica
Agentkid,
I know something about tank cars so will answer your question that way. Your car was likely ARA/CTC III specification which was later, after 1927 IIRC, known as Spec 103. Design pressure would have been 60 pounds per square inch and safety valve start to discharge 35 pounds. The car may or may not have been insulated. If tank bands were visible going over the top of the tank it was uninsulated. If the bands disapeared under the jacket the car was insulated.
I doubt that the car was pressurized. If I understand what you are saying the car was loaded about 12 hours before it got to you and the water was peddled out to all the stations the local served. I suspect that the heat in the mass of water was sufficient to keep it above freezing. Freezing of the hose would be possible, but the old screw style bottom outlet valves in those cars always leaked. I have no idea to what standard the railroad would have maintained them.
I think you mentioned not being able to get the water out. That implies to me that the car did not have a vacuum breaker. If the manway cover had a good gasket, and was closed tightly, a vacuum would develop as water was withdrawn. That is why you have to let air into the container of your favorite beverage if you want more liquid out.
The car may or may not have had heater coils. The last thing I would expect would be trying to heat the car using the coils in transit. You would need a steam line from the locomotive to the coil inlet which would have been on the bottom of the tank near the center of the car. This would be at least 50-60 feet of hose strung along the loco walkway and the car’s walkway. In the US that would be bait for the ICC safety appliance man. In Canada, I know not.
Carl - The heater coil inlet and outlet connections are a