London Fire

[Andy™]

interesting read here  http://www.skyscrapercity.com/showthread.php?t=2007285

 

[apprentice87]

wet risers for that height,

Hi Andy, I know that for really high buildings they have wet risers instead of dry ones, but why is that?? I would have thought that a fire engine can pump water to a much higher head than the municipal water mains??

john..

 

[steptoe]

OK,

I've just done some works for a company and some of that involved high rise,

BTW, I don't work for that company anymore, due to the following among other reasons,

Reinstating fire barriers is not in our price, so don't worry about it,

Put one fire clip in each cable, that's all we priced to do

I'd you notice anything that isn't on the EICR ignore it, just say remedials carried out ,  refer to previous EICR

:shakehead

I dread to think anything like this would happen, but that's why I left.

 

[Sharpend]

What I never understand in these situations is why people don't just start flooding the place? Given that the electricity would have been cut off??

 

[Lurch]

Hi Andy, I know that for really high buildings they have wet risers instead of dry ones, but why is that?? I would have thought that a fire engine can pump water to a much higher head than the municipal water mains??

Possibly because of the amount of water and the time needed to get it up to where it is needed? Probably find some larger buildings would empty an engines tanks just priming the line.

 

[M107]

Hi Andy, I know that for really high buildings they have wet risers instead of dry ones, but why is that?? I would have thought that a fire engine can pump water to a much higher head than the municipal water mains??

john..

The water is pushed through the base pump (appliance) & up the dry risers at 10 bar.

 

[M107]

Possibly because of the amount of water and the time needed to get it up to where it is needed? Probably find some larger buildings would empty an engines tanks just priming the line.

The appliance connects in to the hydrant (mains) with twin hose lengths & connects to the dry riser inlets, the pump operator then charges the riser when requested.

 

[M107]

What I never understand in these situations is why people don't just start flooding the place? Given that the electricity would have been cut off??

An already unstable structure will be made worse with the weight of water sloshing through it.

 

[Lurch]

The appliance connects in to the hydrant (mains) with twin hose lengths & connects to the dry riser inlets, the pump operator then charges the riser when requested.

I suppose that makes sense, I'd imagine they have ample mains hydrants specified along with the dry riser so they know they can just bring a pump in and have it connected and working?

 

[phil d]

Any pump has a maximum 'head', this is the maximum height that it can lift water to,beyond this limit it becomes difficult to actually raise the water, in the case of risers, it's the static head that is the overriding factor not the pressure. On high rise buildings this issue can affect mains water pressure and it is not uncommon on very high buildings to have multiple boost pumps in the rising main.

 

[phil d]

I suppose that makes sense, I'd imagine they have ample mains hydrants specified along with the dry riser so they know they can just bring a pump in and have it connected and working?

When I was involved with the fire service, the issue we had with large fires was that there are a number of hydrants connected to the same main, the more pumps you connect the lower the pressure. We had one big job and we effectively robbed all the water that was meant to feed domestic properties. in some area's deemed high risk the hydrants are actually on their own water main, this was fairly common years ago, but due to costs it's now only done in special circumstances.

 

[binky]

LFB, not checing buildings, and insufficient fire mains hydrants. Could that be due to cutting public service funding?

 

[Andy™]

Hi Andy, I know that for really high buildings they have wet risers instead of dry ones, but why is that?? I would have thought that a fire engine can pump water to a much higher head than the municipal water mains??

john..

pressure drop, same as voltage drop. if you pump 10 bar of water in at ground level then at 50mtr you only have 5 bar at your hose

wet risers are not connected to the mains water. they have their own dedicated tanks and pumps

 

[phil d]

LFB, not checing buildings, and insufficient fire mains hydrants. Could that be due to cutting public service funding?

The reduction in 'separate feed' fire hydrants was due to increased levels of fire safety, allegedly. As for building checks I think it isn't a case of less buildings being checked, more a case of standards slipping, which as we all know seems to be happening in all sectors these days.Sadly on this occasion it has cost lives.

Incidentally each floor, of which there were 26, contained 6 flats, now if we take an average occupancy of 4 tenants per flat, that equates to some 624 people, even allowing for people who escaped, people who were not at home at the time, and the fact that not all flats will have had 4 occupants, there is still potential for the loss of one hell of a lot of lives. I sincerely hope this is not the case .

pressure drop, same as voltage drop. if you pump 10 bar of water in at ground level then at 50mtr you only have 5 bar at your hose

wet risers are not connected to the mains water. they have their own dedicated tanks and pumps

An excellent way of describing it Andy.

 

[apprentice87]

wet risers are not connected to the mains water. they have their own dedicated tanks and pumps

Ahhh, now i understand..

john..

 

[apprentice87]

I remember years ago, the fire brigade would come around all the time and put a standpipe on the hydrant adn blast the thing for 5 minutes to clean it out i suppose. Never see that now.. The other day, i connected a 2 1/2" standpipe to the hydrant across the road from my house and opened it up. For about 5 seconds the water was pitch black, and then a double handful of stones shot out of the thing.. Just what the fire pump needs.....

I was at the hospital the other day and the fire brigade turned up [false alarm] I asked them about the testing of the hydrants and they said it is down to the "water board" now. Big surprise, but the "water board" not not care, and never do it at all..

It is like everything else, nobody, apart from the front line staff that have to sort out the ****, care about anything...

john...

 

[Andy™]

depends on the hydrant iirc, if its marked FH then its the fire brigades responsibility, if its marked WO then its the water board. if you have a stand pipe then you can only legally use those marked WO

 

[apprentice87]

Ahh, There are some very old enamel signs at the hospital that say "FH" all the others there, like the one across from my house, have the big "H" and the size of the main and distance to the thing itself marked on them..

john..

 

[Tony S]

Our company made the hydrant castings. Water boards provided the hydrants as a public service. It all changed with privatisation, the bottom dropped out of the market when the fire brigade had to pay to have them installed. There was talk at the time of the companies wanting to charge the brigades water rates.

 

[phil d]

depends on the hydrant iirc, if its marked FH then its the fire brigades responsibility, if its marked WO then its the water board. if you have a stand pipe then you can only legally use those marked WO

The FH and WO come from the old days when there were separate mains, Water pumped into the main marked FH or fire hydrant, wasn't treated and as such unsuitable for drinking. The other one WO, water outlet, could be used for drinking as it was fed off the potable water main.We used to use hydrants occasionally when doing drain work, the brigade never objected as we'd report faulty hydrants as we found them, now however it's down to the water authority and all standpipes have to have meters fitted to them, you must have a licence to take water from a hydrant and the meter on the standpipe is read and you are billed at regular intervals.

Some years ago I held the maintenance contract for a fairly large firm in our area,they had a sprinkler system and hydrants fed from a separate main. One of my jobs was to inspect the fire fighting equipment, at various places around the site they had cabinets containing, standpipes, hoses, jets and branches. I would go round on a monthly basis,check all the equipment in the cabinets was there and in good order, then I'd test each hydrant to make sure it was clear and working. To be honest it was a good little number, especially on a warm summers day.

One day after an inspection by the fire brigade, (they'd a new chief and he was getting to know his patch) I was told to remove all the fire fighting equipment. Apparently the brigade no longer approve of in house fire fighting teams, as it has led to delays in calling out the brigade (people trying to fight a fire that they should have called the brigade to) I was told to dispose of all the gear, it was all proper kit and quite expensive, I couldn't bring myself to skip it all, so being as I was involved with the local brigade as a volunteer incident support officer, I took all the gear to my station and it was used by the fire cadets for training with.