4 Wheeled tank wagons.

[D2100]

Rule 240 mentions a barrier truck.
First thought is the as you get further from the engine the sparks would get less and smaller so not enough to ignite any part of the trailing atmosphere around the tanks.
Maybe they also recognised if a tank was next to the engine/tender that a flammable atmosphere could potentially form in the low pressure area between the tank and engine/tender rear and pose a greater fire risk. An open truck would prevent such a low pressure area forming easily so again the mixture would be too lean to burn.

Alan, whilst I'm not discounting that reasoning at all, I believe the use of barrier wagons was at least in some part to provide a 'crumple zone' in the event of an accident. This being supported by their presence at the rear as well as the front. Also, barriers were not always open wagons; certainly by the '60s, vans were probably just as common and in the '70s, certain vans were set aside for barrier use (albeit with chemical trains by that time, rather than oil products).

[1H was 2E]

Alan, whilst I'm not discounting that reasoning at all, I believe the use of barrier wagons was at least in some part to provide a 'crumple zone' in the event of an accident. This being supported by their presence at the rear as well as the front.[/quote]

The barrier wagons situation was something that puzzled us in the '60s. We took a cynical view - an early example of "it's elf and safety gone MAD"
Quite often around our way, the "barrier" was 2 fitted plate wagons. They didn't provide much of a spark barrier (vans would have been better) but, in the event of a collision, their sturdy construction would surely have resulted in buffers over-riding and the first tank being punctured.

The logic for use at rear was perhaps to distance the brake van; either because of the stove, or sparks from brakes.

However, these considerations apply to block trains of petroleum products; rafts of tank wagons formed in trains used the other traffic as "barriers" and, because of marshalling for attach/detach, might not be near the front or rear.

I'll have to have a dig for 240 in a rule book that pre-dates block trains.

[2502]

Once again many thanks for time, interest, & replies, RON

[2502]

Since posting this query ,in Railway World Jan 85 is a report of arunaway @ M/C Victoria 11/12/47.Train consisted of a runner, 20 Full tanks a rear runner & a 20 ton brake van.Total weight 593 tons.The guard pinned down the rear runner but regulations prevented him from pinning down the tanks wagons .The fireman should have pinned down front runner but was prevented by the driver , as unnessesary.This seems to answer my original query. The tanks contained petrol.RON

[Seagull]

Well done Ron for finding the report. If anyone is interested it is here.

At the top of page 4 it states:- 'Hand brakes of tank wagons loaded with spirits must not be pinned down for braking purposes on inclines'

Spirit was the generic term used to describe liquid cargoes that wre more volatile (flammable).

So it appears it was the risk of sparks from the brakes they were concerned about and the barrier wagons were there to provide brake power.

Alan

[john coffin]

I think one of the reasons most 60's and early 70's petrol stations smelt was the fact that most pumps were either hand worked, by an attendant, or
indeed in some cases by hand pump, and the nozzles did not have the same kind of cut off that they have now. Also, of course, leaded petrol had a much more interesting smell than modern stuff. In addition, many of the cars around during that time had awkward fillers,and the tract was often a place in which petrol could hide, giving off an odour too.

Paul

[Colombo]

This seems a good opportunity to remind everybody about the Summit Tunnel fire in 1984: http://en.wikipedia.org/wiki/Summit_Tunnel_fire.

Petrol tankers were derailed and ignited from a hot wheel bearing in a tunnel.

Also an empty petrol or distillate oil tanker is more dangerous than a full one, even after venting, because the petrol permeates the internal surface of the tank and it takes steam treatment to clear all explosive vapours. The same applies to a car fuel tank or a loco fuel tank for that matter. However a pool of diesel oil will extinguish a lighted match plunged into it.

It is not the liquid fuel that explodes, but the mixture of fuel vapour and air.

Colombo

[D2100]

So it appears it was the risk of sparks from the brakes they were concerned about and the barrier wagons were there to provide brake power.

[my bold]

I'm not sure I read it like that Alan, or at least not in such explicit terms - have I missed something? The only reference to increasing braking capability I can see is about requesting a second loco.

[Seagull]

I'm not sure I read it like that Alan, or at least not in such explicit terms - have I missed something? The only reference to increasing braking capability I can see is about requesting a second loco.

The early part of the report mentions that the brake was pinned down on the wagon next to the brake van, but the driver did not think it necessary to pin the brake down on the wagon next to the engine [page 2 paragraph 6 of the narrative]. ie. The extra wagons were there to augment the braking capacity of the engine and brake van.

Alan

[1H was 2E]

As well as Summit Tunnel, Eccles (4th December 1984) also involved the ignition of the contents of tank wagons; in this case, containing fuel oil, generally regarded as difficult to ignite.

The reference to an instruction that brakes should not be pinned down on tank wagons descending inclines is interesting in that I have not been able to locate it where it might be expected to be found - in Sectional or Regional Appendices. Curiously, too, looking at Rule 240 in a pre 1923 rule book (RCH) and also in the LMS 1933/38 one there is almost no reference to inflammable liquids in tank wagons, the rule being headed "Conveyance by goods trains of explosives and dangerous goods" and generally refers to containers of these commodities being loaded in wagons, rather than bulk carriers. The only specific mention of tank wagons is included with vehicles containing the items covered and stating that they should be marshalled as near the middle of the train as possible. Of course, block trains of petroleum products were unheard of until recent times.

Looking at my photos of the Immingham-Northampton "Gas Train" (which, as previously mentioned, conveyed Saharan natural gas to the gas works for distribution by the town gas infrastructure) there were no barrier wagons - loaded tanks were conveyed next to the loco. And the contents certainly burnt when they got to our cooker...

[Seagull]

in this case, containing fuel oil, generally regarded as difficult to ignite.

Anything will burn if you get it hot enough for long enough - even steel.

I see from the report into the Eccles accident that the product carried was gas oil. The name is applied to a range of products. The lighter end is heating oil that some people use for their central heating systems. The middle range is DERV Diesel engine road vehicle - what you put in your motor Guvnor. And the heavier end is used in smaller marine diesel engines, such as in fishing boats, small ships engines and big ships generators.

The clue is in the first word of the name:- 'gas'
If sprayed through a nozzle it readily breaks down into small droplets that are easily ignited, not actualy gas but vapour (When it was named they were less particular about names and gas and vapour were thought to be the same thing by most people).

The freight train was doing about 10 MPH and it was hit from the rear by the passenger train, which the report states was doing about 50 MPH at the time of the collision. Three tank wagons were de-railed and ruptured by the force of collision. It's a fair bet that there was plenty of vapour and the report states that the ignition source was the hot exhaust pipe of the passenger locomotive, which would have been right in the middle of the vapour cloud.

I rest my case m'lud.

Alan

[D2100]

I'm not sure I read it like that Alan, or at least not in such explicit terms - have I missed something? The only reference to increasing braking capability I can see is about requesting a second loco.

The early part of the report mentions that the brake was pinned down on the wagon next to the brake van, but the driver did not think it necessary to pin the brake down on the wagon next to the engine [page 2 paragraph 6 of the narrative]. ie. The extra wagons were there to augment the braking capacity of the engine and brake van.

Alan

Thanks Alan. Don't like reading PDFs, I obviously missed that.

[adrianbs]

Hi All There have been other on shore oilfields in existence for well over 60 years at least. One small one was (and is ?) in Dorset long before the deep wells were discovered and was on the coast south of Wareham near Kimmeridge with just one nodding donkey. The crude was road tankered to Wareham where, in steam days I remember in the 50s and 60s, there were always 2 or 3 black tankers waiting to be loaded. Some of these rail tanks were real vintage wagons with wood undeframes and small tanks. I have a feeling this might have been the first largish oil well in the UK. adrianbs

[richard]

The 'donkey at Kimmeridge Bay is still operational. For a while, persistent production was a bit of a puzzle, but it appears to be fed by a number of small interconnected reserves. Every week or so, a road lorry takes the oil to the Wytch Farm operations (Wytch Farm is the largest onshore field in Western Europe).

It is right ton the edge of the Naval firing range - I may have a picture somewhere from the early 1990s with the range flag, (somehow they didn't trust cliff walkers to heed the flag!), and donkey all in the same shot.

By coincidence, the Kimmeridge Clay which outcrops down in the bay is the main source rock for the North Sea fields...

[1H was 2E]

Perhaps a little clarification is helpful.
The LNER General Appendix (I'll quote the 1/11/47 one) says;
[/TANKS CARRYING HIGHLY INFLAMMABLE LIQUIDS (CLASS A)b]

Tanks containing highly inflammable liquids (Class A) are painted in lead colour with the solebars painted red. These wagons must be dealt with in accordance with Rule 240.

The next paragraph ("TRAVELLING OIL TANKS AND RESERVOIRS") concerned with loading and discharge makes it clear that "Highly Inflammable Class A" refers to "Motor Spirit Etc.". It the goes on to refer to "Inflammable Liquid Class B (Heavy Oil etc.)", which are subject to less stringent rules.

By Motor Spirit is meant petrol and by Heavy Oil is meant diesel (old bus log books showed fuel as H.O. if it was a diesel).

So it's only petrol tankers that need, for instance, barrier wagons; the Eccles collision involved gas oil/diesel/heavy oil tankers, explaining the lack of barrier wagons.

As an aside, model tank wagons produced commercially seem to be finished in silver rather than grey.

But to return to the original question, of whether a particular wagon was fitted, it should be borne in mind that a fitted PO wagon would cost more to build than an unfitted one. This additional cost (and subsequent increased maintenance) would provide no benefit to the owner if the wagons were conveyed in small numbers on network trains. It was only with the introduction of block trains composed of one trader's wagons that any benefit would arise, namely the ability to shorten transits by faster running. PO wagons, regarded by the enthusiast as part of some lost idyllic pre war world, were often poorly maintained and improvements that cost money (brake handles on both sides, oil axleboxes for examples) were only made through gritted teeth and under legislation.