Discussion:
Tank cars
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C. Dewick
2008-06-15 07:47:13 UTC
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Can someone tell me the reason for tank cars of apparently similar capacity
having one, two and three domes? Is it for the carriage of different grades
of material in the same car?
Generally yes, though these days a tank car only has one type of commodity
when in service. The extra domes can still be useful for cleaning and all
tank cars contain baffles to dampen the movement of the liquid contents so
domes can serve as accesses to each section of the tank in between baffle
groups.

Craig.
--
Craig Dewick - HO-Scale Railway Modeller and Professional Train Manager at
http://lios.apana.org.au/~craigd or ***@lios.apana.org.au if you're game!
RailZone Australia - http://www.railzone.org - No Fundies! No RailCorp CodeCon!
http://lios.apana.org.au/mailman/listinfo/aus_rail_safety for Oz Rail Safety
Bill Whale
2008-06-19 13:06:18 UTC
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And the next question is, why do modern tank cars have no domes?

............................................................Bill
Post by C. Dewick
Can someone tell me the reason for tank cars of apparently similar capacity
having one, two and three domes? Is it for the carriage of different grades
of material in the same car?
Generally yes, though these days a tank car only has one type of commodity
when in service. The extra domes can still be useful for cleaning and all
tank cars contain baffles to dampen the movement of the liquid contents so
domes can serve as accesses to each section of the tank in between baffle
groups.
Craig.
--
Craig Dewick - HO-Scale Railway Modeller and Professional Train Manager at
RailZone Australia - http://www.railzone.org - No Fundies! No RailCorp CodeCon!
http://lios.apana.org.au/mailman/listinfo/aus_rail_safety for Oz Rail Safety
b***@earthlink.net
2008-06-24 16:34:13 UTC
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On Thu, 19 Jun 2008 23:06:18 +1000, "Bill Whale"
Post by Bill Whale
And the next question is, why do modern tank cars have no domes?
They do have domes, they're just not as big as on the older cars. All
the dome was was a cover for the valves. But a lot of cars now do
have a small cover over the valves. Depends on the car
Howard Garner
2008-06-25 01:36:25 UTC
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Post by b***@earthlink.net
On Thu, 19 Jun 2008 23:06:18 +1000, "Bill Whale"
Post by Bill Whale
And the next question is, why do modern tank cars have no domes?
They do have domes, they're just not as big as on the older cars. All
the dome was was a cover for the valves. But a lot of cars now do
have a small cover over the valves. Depends on the car
Not right!
The dome was for the expansion of the product. It may also have covered
various valves, etc.
Today the control the loading to provide for the expansion, yesterday
the filled the shell of the tank andthe dome took care of the expansion.

Howard Garner
Len
2008-06-26 11:03:16 UTC
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"Howard Garner" <***@bellsouth.net> wrote in message news:igh8k.11993$***@bignews2.bellsouth.net...
: ***@earthlink.net wrote:
: > On Thu, 19 Jun 2008 23:06:18 +1000, "Bill Whale"
: > <***@optusnet.com.au> wrote:
: >
: >> And the next question is, why do modern tank cars have no domes?
: >>
: >
: > They do have domes, they're just not as big as on the older cars.
All
: > the dome was was a cover for the valves. But a lot of cars now
do
: > have a small cover over the valves. Depends on the car
:
: Not right!
: The dome was for the expansion of the product. It may also have
covered
: various valves, etc.
: Today the control the loading to provide for the expansion,
yesterday
: the filled the shell of the tank andthe dome took care of the
expansion.
:
: Howard Garner

I loaded tank cars at Pfizer Chemicals some years back. All I ever
saw under the domes was pipes and pressure gauges. We had strict
rules about how much material could be loaded into a car specifically
to prevent expansion spills or tank/pipe ruptures.

I never got a good explanation why, but several materials were
actually loaded through the 'discharge' valve on the bottom of the
car. The air in the car vented out through a pipe on the top as it
filled. It was your job if you overfilled and blew material out the
top.

Len
Wolf Kirchmeir
2008-06-27 01:35:16 UTC
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Len wrote:
[...]
Post by Len
I never got a good explanation why, but several materials were
actually loaded through the 'discharge' valve on the bottom of the
car. The air in the car vented out through a pipe on the top as it
filled. It was your job if you overfilled and blew material out the
top.
Len
I suspect it was to reduce venting of gases. In you fill through the top
valve, then gases from the fluid will mix with the air being displaced
and vented outside the tank.
--
wolf k.
Dan Merkel
2008-06-27 13:08:09 UTC
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Post by Wolf Kirchmeir
[...]
Post by Len
I never got a good explanation why, but several materials were
actually loaded through the 'discharge' valve on the bottom of the
car. The air in the car vented out through a pipe on the top as it
filled. It was your job if you overfilled and blew material out the
top.
Len
I suspect it was to reduce venting of gases. In you fill through the top
valve, then gases from the fluid will mix with the air being displaced and
vented outside the tank.
--
wolf k.
I'm not sure how tank cars are filled, but it may be that filling from the
bottom also minimized the disturbance of the material being loaded. If you
use a hose to fill a water bucket, as the water shoots into the bucket from
above, the water is stirred considerably and makes a lot of bubbles, etc.
If you submerge the end of the hose. the water is still agititated but not
nearly as much.

Like I said, just a thought as I really don't know how it is done...

dlm
Val
2008-06-27 14:59:38 UTC
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Post by Wolf Kirchmeir
[...]
Post by Len
I never got a good explanation why, but several materials were
actually loaded through the 'discharge' valve on the bottom of the
car. The air in the car vented out through a pipe on the top as it
filled. It was your job if you overfilled and blew material out the
top.
Len
I suspect it was to reduce venting of gases. In you fill through the top
valve, then gases from the fluid will mix with the air being displaced and
vented outside the tank.
--
wolf k.
I'm not sure how tank cars are filled, but it may be that filling from the
bottom also minimized the disturbance of the material being loaded. If you
use a hose to fill a water bucket, as the water shoots into the bucket from
above, the water is stirred considerably and makes a lot of bubbles, etc.
If you submerge the end of the hose. the water is still agititated but not
nearly as much.

Like I said, just a thought as I really don't know how it is done...

dlm

~~~~~~~
Also, filling from the bottom, with less agitation of the product, can
reduce static electricity buildup and vaporization of the liquid. Note that
large aircraft are fueled from the bottom. It's not just for the
convenience of the workers.
Val

mark
2008-06-27 02:45:15 UTC
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Post by Len
: > On Thu, 19 Jun 2008 23:06:18 +1000, "Bill Whale"
<snip
Post by Len
I loaded tank cars at Pfizer Chemicals some years back. All I ever
saw under the domes was pipes and pressure gauges. We had strict
rules about how much material could be loaded into a car specifically
to prevent expansion spills or tank/pipe ruptures.
I never got a good explanation why, but several materials were
actually loaded through the 'discharge' valve on the bottom of the
car. The air in the car vented out through a pipe on the top as it
filled. It was your job if you overfilled and blew material out the
top.
My wife says that some of the heavy diesels would work, loaded that way, but
she can't think of anything else. (Her stories with loading tankers, train
and other, usually have to do with things like lox and hydrazine....)

mark
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