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Post by 1938 on Jun 19, 2009 0:50:24 GMT
Hilary Benn's speech today on the changing climate, London in particular being sited to suffer increased summer heat, are the designers of new rolling stock taking this into account? Does anyone agree with me the drop lights, as on the A & D stock like the past 38 & 59 tube stock give better ventilation!
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Post by Deleted on Jun 19, 2009 2:26:48 GMT
The New S Stock on the Met. District and Circle lines are going to be air conditioned.
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Post by Deleted on Jun 19, 2009 8:25:59 GMT
The New S Stock on the Met. District and Circle lines are going to be air conditioned. Fantastic. The world is getting hotter because of the use of too much power, so we fit the trains with devices that use more power. And then, of course, the covered stations will need air conditioning to get rid of the heat pumped out of the trains' units. Insanity.
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Post by Deleted on Jun 19, 2009 8:34:45 GMT
Hilary Benn's speech today on the changing climate, London in particular being sited to suffer increased summer heat, are the designers of new rolling stock taking this into account? Does anyone agree with me the drop lights, as on the A & D stock like the past 38 & 59 tube stock give better ventilation! These new trains are the equivalent of putting us all in a huge plastic bag and leaving us to stew. I hate the idea of sealed units and no natural air flow. It's perfectly fine having sealed air con system thats flown around the car via blowers and ventilators. However the system is open to contamination... dust and muck gets sucked into the vents, there might be a thriple stage or quad stage filtration process, but microscopic particules will still get through. yes, the system might 'refresh' the air in the car every x/hours but you'll still end up with the same problem. Nothing beats the satisfaction of having a nice blast of air drifting across the face. Now you can tell, I used to break the rule of sticking me head out of the window on the smal door trains. If you look back in the archives, manual door stock trains on the underground used to run with the doors OPEN during hot weather. Something I found amazing when I first found this out, especially being brought up in this 'mollycuddled/wrapped in cotton wool with kneepads' type culture. I then realised that people weren't so silly as to mess about then; they realised the danger and stayed clear. I'm sure accidents did happen at times, but have not heard of any myself. Hmm... how to cool the tube? Install tons of equipment that pumps out more heat during its own attempts to cool the air around it... thus defeating the whole idea.
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Phil
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Post by Phil on Jun 19, 2009 8:38:51 GMT
Fantastic. The world is getting hotter because of the use of too much power, so we fit the trains with devices that use more power. And then, of course, the covered stations will need air conditioning to get rid of the heat pumped out of the trains' units. Insanity. We are talking the SSL here so the stations and (partly open) tunnels are well able to rid themselves of the excess heat. But on the wider point (and it was on the Beeb yesterday) the whole concept of the heat in the tube part is becoming serious. Apparently if the earth keeps warming, and nothing is done to the tube network, the tube lines will become unusable in summer in a few (unspecified) years because temperatures will be above survivable limits. So doing nothing seems not to be an option....
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Chris M
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Post by Chris M on Jun 19, 2009 10:20:42 GMT
Has anyone heard whether the groundwater cooling trials at Victoria (iirc) were sucessful or not, and if so is that going to be rolled out?
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Post by Chris M on Jun 19, 2009 10:23:01 GMT
If you look back in the archives, manual door stock trains on the underground used to run with the doors OPEN during hot weather. Something I found amazing when I first found this out, especially being brought up in this 'mollycuddled/wrapped in cotton wool with kneepads' type culture. On that point you might be interested to read this BBC News article headlined "Schools 'too safe' teachers say "
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mrfs42
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Post by mrfs42 on Jun 19, 2009 11:15:30 GMT
Just idly musing.......
I wonder if the heat could be used as something akin to geothermal energy......
I suppose the real pain would be excavating for the grid of pipes to act as a heat exchanger.
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Phil
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Post by Phil on Jun 19, 2009 13:59:59 GMT
If you look back in the archives, manual door stock trains on the underground used to run with the doors OPEN during hot weather. Something I found amazing when I first found this out, especially being brought up in this 'mollycuddled/wrapped in cotton wool with kneepads' type culture. I then realised that people weren't so silly as to mess about then; they realised the danger and stayed clear. I'm sure accidents did happen at times, but have not heard of any myself. Here we are - that's the 3rd time this pic has been put on the forum. (For the anoraks, try to track down the other 2 - one was not that long ago....)
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Colin
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Post by Colin on Jun 19, 2009 14:43:57 GMT
East Putney. Ooppss, sorry, wrong thread! ;D ;D ;D ;D Anyway, Artery raises the point that the air con will push around poorly filtered air - well the 09ts (and probably others but I don't know enough about other stocks to name them) will use forced ventilation. So the saloons will be full of the muck lurking in the deep level tubes........I dunno what's worse. As for the Victoria trial.....pass
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Post by pakenhamtrain on Jun 20, 2009 2:55:29 GMT
I will admit having A/C in the underground stations might not be as good an Idea as you think.
The 3 underground stations we have(4 if you count Box hill) All have A/C. Granted the station is cooler than outside but by not that much. Unless your actually standing under the vent it really has no effect. You still feel rather hot.
Of course any effect of the A/C gets cancelled out when a train comes into the station and pushes all the hot air from vent shafts and A/C pods with it!
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Phil
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Post by Phil on Jun 20, 2009 9:12:56 GMT
For the tube lines the technology is nearly (and has been so for too long a while) developed for a 'heat storage' system like night-storage radiators, where excess heat in the train is mopped up and stored whilst in the tunnels then 'dumped' once in the open.
But it's the usual problem - the storage devices take a lot of space and we are talking tube stock dimensions. Which is why it is nowhere near being ready.
If some genius could solve that one, TfL could get round the heat problem on all lines but the Vic.
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Post by 100andthirty on Jun 20, 2009 11:12:25 GMT
For the tube lines the technology is nearly (and has been so for too long a while) developed for a 'heat storage' system like night-storage radiators, where excess heat in the train is mopped up and stored whilst in the tunnels then 'dumped' once in the open. But it's the usual problem - the storage devices take a lot of space and we are talking tube stock dimensions. Which is why it is nowhere near being ready. If some genius could solve that one, TfL could get round the heat problem on all lines but the Vic. The idea is that a normal air conditioner is used but bigger than usual. The surplus capacity is used to cool a tank of "phase changing medium" (a posh term for water with a chemical that slightly modifies its freezing point). The cold tank is then used to cool the train when in the tunnel and the air conditioning can be turned off to save pumping more heat into the system. There has to be enough open running to allow the system to cool the water tank sufficiently. Thus it's not just the Vic, but also W&C, and the Bakerloo Queen's Park service and any other short trip reversers. Also account has to be taken of the extra electricity used to carry around the higher weight of the larger system - so it's not all gain!
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Post by 1938 on Jun 22, 2009 0:01:30 GMT
These new trains are the equivalent of putting us all in a huge plastic bag and leaving us to stew. I hate the idea of sealed units and no natural air flow. It's perfectly fine having sealed air con system thats flown around the car via blowers and ventilators. However the system is open to contamination... dust and muck gets sucked into the vents, there might be a thriple stage or quad stage filtration process, but microscopic particules will still get through. yes, the system might 'refresh' the air in the car every x/hours but you'll still end up with the same problem. Absolutely right, unless the system is perfectly maintained there will also be a higher risk of cross infection cold and flu viruses etc.
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mrfs42
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Post by mrfs42 on Jun 23, 2009 23:18:23 GMT
Absolutely right, unless the system is perfectly maintained there will also be a higher risk of cross infection cold and flu viruses etc. I'd like to see some hard, empirical evidence for this, actually. I can't immediately find anything that relates to "nosocomial" type or community-acquired infection that can directly be attributed to air conditioning and public transport (I am quite deliberately discounting Legionella pneumophila infections[1]). I strongly consider that the movement of air and the population density in the Underground are already quite adept at cross-contamination and harbouring airborne pathogens - the recirculating air worries are a bit of a red herring IMHO. FWIW it was an absolute joy travelling on the '38 stock over the weekend with the windows open! ;D ;D If anyone can find a report from 'The Lancet' or similar, I'd be everso grateful. [1] but including delightful organisms as Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Kliebsella varieties ( K. pneumoniae) and Stenotrophomonas maltophilia. Ah. (slinks away)
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slugabed
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Post by slugabed on Jun 23, 2009 23:57:09 GMT
I can't quote chapter and verse,but at Architecture school in the 80s we were taught that the humidifier plant necessary for air-conditioning,provides a perfect environment (warm,damp mist) for the reproduction of nasties.This was shortly after the introduction of regulations to prevent the spread of legionella,which required regular (yearly?) replacement of the water used,and that this water contain a dissolved disinfectant Even so,we were told,the water in the tanks often resembled a gloop,with algae growing in the spraying areas.This had to be cleaned by some lucky operative in protective clothing. In an air-conditioning unit,the inducted air is blown through a mist of this "water",to replenish that lost by condensation during cooling (though,in practice,the condensate is scavenged for spraying) and,coupled with the "closed loop" described by the re-circulated air in a modern sealed building,the possibilities for multiple re-infection are self-evident. The same goes for modern (post 1970s) aircraft wherein,to save drag,the old total-loss system of ventilation was ditched in favour of a re-circulating system.Airline unions have grumbled about the health effects of this decision on cabin staff ever since,though again this may be anecdotal in nature. The upshot is,that air-conditioned spaces certainly have a case to answer in terms of health,compared to spaces (like the A-Stock) where one can simply open the window. I don't subscribe to the Lancet,perhaps an article has been written about this there,but I've been slightly revolted by the thought of air-conditioning ever since (would you lick the back of your fridge,even if a doctor said it was "perfectly safe") without getting into the arguments about energy consumption and dodgy coolants,all for the couple of weeks in the year when cooling may be desirable. But then,air-conditioning was never really designed for people's benefit,rather to provide a stable working temperature for computers.......
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Phil
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Post by Phil on Jun 24, 2009 7:59:40 GMT
That's all absolutely right. But I'm not sure that with the expected ramming-full loadings a humidifier would be needed at all. Humans give off water vapour (polite term) and I could conceive that a-c units for LU might actually need DEhumidifiers. Just a scientific guess here, but possible. Also, I doubt if a closed-loop system would be needed: an open-loop system would be far easier to install in this setup with lots of naturally 'moving' external air.
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Post by 100andthirty on Jun 24, 2009 11:09:40 GMT
That's all absolutely right. But I'm not sure that with the expected ramming-full loadings a humidifier would be needed at all. Humans give off water vapour (polite term) and I could conceive that a-c units for LU might actually need DEhumidifiers. Just a scientific guess here, but possible. Also, I doubt if a closed-loop system would be needed: an open-loop system would be far easier to install in this setup with lots of naturally 'moving' external air. An air conditioner is, effectively a de-humidifier. As air is cooled, the about of water it can absorb reduces, and the excess is deposited as waste water as air passes over the evaporator. Typically a modern train air conditioner recycles 75% internal air and mixes it with 25% external air. However, there's a big BUT for metro systems. Every two minutes or so, the doors open and this allows a lot more outside air to mix with the cooled air.
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slugabed
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Post by slugabed on Jun 24, 2009 12:41:57 GMT
From what I remember,we were told that de-humidified air,direct from the cooler,really IS a health risk,causing damage to the mucous membranes of those breathing it in,resulting in illness.Admittedly,this was in a sealed building environment. The fact that people,ahem,exude water vapour in quantity is central to my point about the hygiene (or otherwise) of air-conditioning.What happens to this water,with its bacterial load? It is condensed on the cooler,is then scavenged into the mister tank,thence to be sprayed in the mister.Remember,the mister tank water must be disinfected,and changed yearly,but it is not a static body of water;indeed,it is being constantly "diluted" by the net effect of losses of disinfected water through spraying,and gains from human exhalation and perspiration.It can't take long for the disinfectant to become so dilute as to be useless,making the mister tank a breeding-ground for nasties which are then pumped around the system. The point made about the doors opening is a very good one,and,I suppose,wuld tend to nullify the cooling benefit of air-conditioning to a great extent,so why bother with the expense...a conclusion which LT seems to have reached with its proposals for forced-air ventilation. Of course,the only real answer is to lower the ambient temperature in the tunnels by improved heat dissipation. Whoever cracls that one,deserves the Nobel Prize.
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Post by 100andthirty on Jun 24, 2009 13:55:38 GMT
From what I remember,we were told that de-humidified air,direct from the cooler,really IS a health risk,causing damage to the mucous membranes of those breathing it in,resulting in illness.Admittedly,this was in a sealed building environment. The fact that people,ahem,exude water vapour in quantity is central to my point about the hygiene (or otherwise) of air-conditioning.What happens to this water,with its bacterial load? It is condensed on the cooler,is then scavenged into the mister tank,thence to be sprayed in the mister.Remember,the mister tank water must be disinfected,and changed yearly,but it is not a static body of water;indeed,it is being constantly "diluted" by the net effect of losses of disinfected water through spraying,and gains from human exhalation and perspiration.It can't take long for the disinfectant to become so dilute as to be useless,making the mister tank a breeding-ground for nasties which are then pumped around the system. The point made about the doors opening is a very good one,and,I suppose,wuld tend to nullify the cooling benefit of air-conditioning to a great extent,so why bother with the expense...a conclusion which LT seems to have reached with its proposals for forced-air ventilation. Of course,the only real answer is to lower the ambient temperature in the tunnels by improved heat dissipation. Whoever cracls that one,deserves the Nobel Prize. train air conditioners in general (although no doubt there's an exception somewhere!) don't have "misters". Water that condenses out of the recycled or fresh air is drained onto the ground.
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Post by Deleted on Jun 25, 2009 12:05:02 GMT
Hilary Benn's speech today on the changing climate, London in particular being sited to suffer increased summer heat, are the designers of new rolling stock taking this into account? Does anyone agree with me the drop lights, as on the A & D stock like the past 38 & 59 tube stock give better ventilation! Yes, drop lights give better ventilation. The argument from management is that when the S stock goes full auto, they don't want the drivers hanging out of the window. The way to overcome this is when the "master control switch" is moved to "auto", the drop lights lock in a closed position, so that they cannot be opened.
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Post by singaporesam on Jun 25, 2009 23:20:23 GMT
Come on , there are lots of Metros around the world with doors opening every 2 minutes and much higher ambient temperatures than in London, the set point in Singapore is 24 degrees !!! if the unit is sized and controlled correctly this isn´t an issue.
As for health risks its pretty well known that the biggest health risks on the train are grabpoles, nevertheless its my understanding that a couple of the A/C suppliers are looking at UV and silver nano to kill the nasties in the same way that the newest home a/c units from LG do.
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Post by 1938 on Jun 26, 2009 11:05:19 GMT
As for health risks its pretty well known that the biggest health risks on the train are grabpoles Perhaps a new topic, ‘Grabpoles are they safe?’ If some people didn’t know that, they should now after the governments advice on the prevention of spreading swine flu. I always make sure I wash my hands as soon as possible after the close encounter.
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bowchurch
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Post by bowchurch on Jun 29, 2009 0:07:23 GMT
I can't quote chapter and verse,but at Architecture school in the 80s we were taught that the humidifier plant necessary for air-conditioning,provides a perfect environment (warm,damp mist) for the reproduction of nasties. AFAIK trains use 'split-system' type air conditioning that does not have this sort of plant. It is more like the units you get in home or small commercial installations, think of it like a scaled up version of your fridge. The units do tend to have some water inside them as a result of the cooling process, but this is a few degrees above freezing which is not a good environment for anything to breed. And it also tends to wash the fan coils out as it is replaced and pumped through the drainage pipes. If the drainage does get blocked though, then sods law says a pint of freezing water will end up over a passengers head next time the train pulls up hard. Whether this is considered an advantage or disadvantage is up to the reader
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Post by singaporesam on Jun 29, 2009 23:32:35 GMT
Split systems are becoming less common on trains these days, a single roof mounted package is considered better because of weight savings, this is a bit like a window type domestic unit. The bigger problem in terms of nasties is mold , as this can form in the ducts and other places. For drainage of water , you typically have two or three drains all of which can take the full amount of condensate.
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bowchurch
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Post by bowchurch on Jun 30, 2009 0:34:02 GMT
Split systems are becoming less common on trains these days, a single roof mounted package is considered better because of weight savings, this is a bit like a window type domestic unit. The bigger problem in terms of nasties is mold , as this can form in the ducts and other places. For drainage of water , you typically have two or three drains all of which can take the full amount of condensate. I'm not convinced the roof mounted boxes are not technically split systems - and I know the units you mean. Its a case of whether you consider a single self contained module containing the condenser and fan cool blowing cold air thorough the roof different to a pair of modules mounted each side of the roof doing the same job. Both work on the same principals of applying Boyle's gas laws, and are both different to the systems that cool by spraying water into the air that slugabed mentioned that have a number of health risks. Either way, I've never seen mold growing inside any of the fan coil or close control air conditioning in the computer rooms I've looked after in the past few years. But I'll concede that the average UK access controlled computer room is a very different environment to a public train in a climate like Singapore.
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Post by Deleted on Jun 30, 2009 21:17:59 GMT
. If you look back in the archives, manual door stock trains on the underground used to run with the doors OPEN during hot weather. Something I found amazing when I first found this out, especially being brought up in this 'mollycuddled/wrapped in cotton wool with kneepads' type culture. I then realised that people weren't so silly as to mess about then; they realised the danger and stayed clear. I'm sure accidents did happen at times, but have not heard of any myself. Yowsers. I wouldn't like to be in a rammed tube train with the doors open whilst moving! Perhaps passenger numbers were much lower back then, meaning most people got a seat and weren't cramming themselves on like sardines...
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Post by Deleted on Jun 30, 2009 22:05:37 GMT
I am all for ventilation as opposed to AC. But it's funny when you open the windows at the end of the carriages; several women scowl as their hair is no longer perfect. All of a sudden there's a little more space twoard the ends of the carriages and for a brief moment, people actually move down toward the centre without having to be asked. Always makes me chuckle!!! ;D
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