Smoke detection in hospital ceiling voids

[paxo2000]

We are trying to prevent a building company from omitting void detection above false ceilings in a brand new hospital
They are trying to use a risk assesment to say that motors,recessed light fittings,UPV pnuematic pipework and fume extract,wiring connections,acoustic thermal insulation,TV amplifiers and phenolic foam are ok
HTM docs give a clear list of what is allowed and then suggest risk assesment
Am i being to keen
any suggestions

[Wiz]

We are trying to prevent a building company from omitting void detection above false ceilings in a brand new hospital
They are trying to use a risk assesment to say that motors,recessed light fittings,UPV pnuematic pipework and fume extract,wiring connections,acoustic thermal insulation,TV amplifiers and phenolic foam are ok
HTM docs give a clear list of what is allowed and then suggest risk assesment
Am i being to keen
any suggestions

Firstly, What category fire system is it?

Secondly, are the voids above/below escape routes or just normal rooms?

Thirdly how deep are the voids?

Lastly, I would imagine, that no matter the depth of the voids, a fire risk assessment might show that at least the presence of motors and amplifiers required the installation of automatic detection.

[Martin]

The contractor is not responsible for your risk assessment. Unless the RP (primary care trust or whoever is the employer) is willing incorporate the reasoning for not having detection in voids into the RPs risk aseessment then the contractors risk assessment i s irrelevant. If however you agree that the risk of not having detection in these areas is acceptable then save the money.
What has the contractor actully put in the risk assessment? if it's just an unsupported statement then it's not really a risk assessment.

[terry martin]

We are trying to prevent a building company from omitting void detection above false ceilings in a brand new hospital
They are trying to use a risk assesment to say that motors,recessed light fittings,UPV pnuematic pipework and fume extract,wiring connections,acoustic thermal insulation,TV amplifiers and phenolic foam are ok
HTM docs give a clear list of what is allowed and then suggest risk assesment
Am i being to keen
any suggestions

If this building is not built yet and in the design stage then they should be building it to current standards.

If they want to deviate from that they need to justify it within their fire strategy report which should accompany their application, a premise of this nature must have one? Within their report they should be providing tangible data proving the deviation from current standards is acceptable.

what have the BC officer or Approved Inspectors said?

If they are proposing a deviation are they using a fire engineering solution?

Can i ask, are you an I.O ? if so pass it on to your Fire Engineering team, if your not then contact the local Fire services Fire engineering team for them to look into it.

[Colin Newman]

I hope this isn't one of mine you're referring to!

It depends how the design team have assessed the items in the ceiling void.  I would expect a detailed assessment of all materials within the ceiling void that are beyond the "accepted" list within HTM 05-03 Part B together with an assessment of potential ignition sources.  On the baisis of a detailled risk assessment it may be acceptable to omit detection.  

If detection can't be omitted I suggest you try to get the project team to provide an aspirating detection system to minimise the issues of lifting ceiling tiles to test and maintain point detection.

[paxo2000]

Its an L1 system of a very big hospital being built to HTM 82
Voids are in all areas of varying sizes even exit routes
It was previously agreed to be L1 system
to me HTM 82 is clear, void detection unless pipes and cables in certain conditions.
The project team have had a risk assesment done listing all the motors etc and saying that they don't prevent much of a risk (not the best risk assesment)
I can't understand why they cannot see it
Even the building control inspector cannot see it
what are your thoughts

Thanks

[jokar]

You either have an L1 system or do not have one. The design can be varied and these variation put into the installation but why you would want L1 and then not keep to the thinking behind it is difficult to assess.  What are they risk assessing, the opportunity of a fire statring and not being detected or the cost of the additional detectors and testing mechanisms?

[Colin Newman]

What risks have you identified?  

I've recently assessed the contents of a hospital ceiling void and there were numerous motors, but found that the motorised valves were energised for about 5 seconds every 8 hours or so and the motors for the fire dampers were only 24vd.c. and were energised only upon test or in the event of a fire.  When I looked at what might be ignited, I found that these motors contained less than 50g of combustible material in their construction and sat in a void surrounded by nothing combustible for a distance in excess of 200mm.  I couldn't envisage that any of these motors could initiate a sequence of events resluting in a fire.

In a similar vein, I found that the pneumatic pipework although PVC was self-extinguishing once the heat sources had been removed and would only breakdown at a temperature in excess of 180 degrees C.  It was routed well away from potential heat sources and the system was fitted with a smoke detector in the blower unit to detect any smoke within the system.  Again, I couldn't envisage an ignition source within the void capable of igniting the pneumatic tube and sustaining its combustion.

In this particular instance I recommended that on balance the risk of potential false alarms and issues regarding the testing and maintenance of ceiling void detection outweighed the potential benefits of installing the void detection since the predominent source of fire would be in the accommodation which was provided with full detection in all rooms.

[Wiz]

Its an L1 system of a very big hospital being built to HTM 82
Voids are in all areas of varying sizes even exit routes
It was previously agreed to be L1 system
to me HTM 82 is clear, void detection unless pipes and cables in certain conditions.
The project team have had a risk assesment done listing all the motors etc and saying that they don't prevent much of a risk (not the best risk assesment)
I can't understand why they cannot see it
Even the building control inspector cannot see it
what are your thoughts

Thanks

As Jokar says you are saying that it is a L1 system, but they want to ignore the recommendation for detection in voids containing motors and transformers. This doesn't make sense to me.

However BS5839 22.2 Note 4 allows the ommission in even large voids where the fire risk is low and on the basis of a variation being agreed.

Conversely BS also recommends that high risk small voids might also require detection when it defintely wouldn't if the risk was low!

In your case unless someone else here can quantify exactly what is a high enough risk then it is down to an argument over what is might be correct.

If someone's argument is that the risk is low and you can't disprove their argument, then I don't know what else you can do.

[Brian Catton]

HTM05-03 partB paragraph 4.6 is very specific and would not allow the omission of detectors in ceiling voids containing motors amplifiers and ceiling fittings. It is all very well saying that the motors or valves may be 24vDC but where are the transformers?

It is the transformers of course that are the hazard items.

This ommision of detection following a risk assessment is a dangerous practice  as a risk assessment is very subjective.

There is a good example in this particular case. If you as a Fire Advisor did a RA you would come up with a different result to the consultant who does not want to install it anyway.

If there is any smoke in a hospital void it should be detected early and not rely on the Fire Service todiscover a burned out choke or transformer.

I would stick to your advice and if the consultant wishes not to take the advice then that is a matter for them.
They will have to underwrite the variation based on their assessment.

[Colin Newman]

HTM05-03 partB paragraph 4.6 is very specific and would not allow the omission of detectors in ceiling voids containing motors amplifiers and ceiling fittings.

Sorry Brian I have to disagree with you there.  The paragraph you reference states ".... detectors need not normally be provided in the following areas:........" it does not state that detcetors can only be omitted in the following areas.  It does however go on to state that "In any case the ommission of detectors should be subject to a risk assessment."

So back to my earlier post, if the motors are 24Vd.c. and the transformers are located within the ceiling void, the transformers would need to be subject to an assessment of the risk they pose.  

Fortunately in the case I referred to the transformers , battery charging circuits and batteries were located in an electrical cupboard.  However, it wasn't the transformers I was concerned about, they were 12VA chasis mounted, shrouded bobbin units with laminated steel cores and housed in a steel box.

As a fire consultant I have no axe to grind as to whether detection is installed in ceiling voids or not.  I don't have shares in a fire alarm company, nor am I on a bonus calculated as a percentage of the project costs I manage to save.  I merely seek to balance the potential risks of omitting detection against the potential risks of UwFS and the problems associated with testing & maintenance.  As you state it is the fire consultant that has to underwrite their risk assessment.

[Brian Catton]

Thanks for those comments Colin. A good balanced view as usual. I think the bottom line is that every case has to be judged on the particular circumstances and therefor the assessed risk.

[Thomas Brookes]

I would have thought with L1 being specified and L1 being the highest level of life protection void protection would be a no brainer.
Soon as any light units are fitted in to a false ceiling and cables run in the void the detection becomes needed.

I also can not see how anyone could say as a minimum have void detection in escape route.

[Colin Newman]

I would have thought with L1 being specified and L1 being the highest level of life protection void protection would be a no brainer.

Thomas, the applicable guidance for hospitals is HTM 05-03 Part B which inerprets the guidance of BS 5839 Part 1 to give specific recommendations applicable to healthcare buildings.  The guidance of HTM 05-03 Part B permits the omission of detection form voids of any depth depending upon the void contents.

[Thomas Brookes]

Don't jump on me as I am not an expert on HTM 05-03, and I don't claim to be.
How ever I quote Executive Summery of HTM 05-03 "It is intended to supplement BS 5839-1 by providing recommendations specific to NHS healthcare premises." not to totally rip up BS5839.

It also goes on to say, "However, the onus rests with the designer to ensure that any other form of fire detection selected ensures that the principles of early detection and warning are maintained, whilst minimising the risk of unwanted fire calls and not compromising the safety of building occupants.

I can not see how a sweeping statement that void detection is not required in hospitals can be anything other than compromising early detection.