Wet Riser Pump back up supplies

[JameZZZ]

Refurb on an existing building where new wet risers are going in:

Where do changeover switches for back up supplies for wet riser pumps have to be installed? Can they be installed at the main switchboar with a single cable to each pump or does the changeover switch have to ne local to the pump with 2 supply cables? Where are there regs on this?

Also I have been told by fire specialist that the supply has to be able to take the locked rotor current of all fire pumps............I have been told that 2 x 75kw pumps are going in with a LRC of 900 amps each! This seems like an unfeasable requirement ( the existing substation which supplies the building is only 1000KVA). Does this also apply to the back-up generator? Has anyone had this thrown at them before?

Any insights are welcome. Thanks

 

[Pete999]

What do the drawings and specifications say, surely a job like this can't be done by word of mouth, there must be some paperwork somewhere.

 

[marconi]

http://www.bafsa.org.uk/wp-content/uploads/bsk-pdf-manager/2017/06/BIF-21-Wet-Dry-Risers.pdf

Please see page 3 of 4 of the BAFSA document on wet riser pumps and their power supplies. It does not answer your question completely but there are some contact numbers at the end of it. If they don't know they might be able to direct you to someone who does.

Also IFEDA - the Independent Fire Engineering and Distributors Association.

See: ifeda.org

I'd have thought BS9990 has something to say on the matter.

Lastly: High rise wet riser fire systems installation | UK Dry Risers - http://www.ukdryrisers.co.uk/wet-riser-systems.php

 

[JameZZZ]

What do the drawings and specifications say, surely a job like this can't be done by word of mouth, there must be some paperwork somewhere.

There is a spec and drawings (layout only) but the spec says things like “supply to specialists requirements”, and the specialist isn’t committing to much.

 

[JameZZZ]

http://www.bafsa.org.uk/wp-content/uploads/bsk-pdf-manager/2017/06/BIF-21-Wet-Dry-Risers.pdf

Please see page 3 of 4 of the BAFSA document on wet riser pumps and their power supplies. It does not answer your question completely but there are some contact numbers at the end of it. If they don't know they might be able to direct you to someone who does.

Also IFEDA - the Independent Fire Engineering and Distributors Association.

See: ifeda.org

I'd have thought BS9990 has something to say on the matter.

Lastly: High rise wet riser fire systems installation | UK Dry Risers - http://www.ukdryrisers.co.uk/wet-riser-systems.php

Thanks for this BS9990 has basically answered my first question. I will call around to clarify.

Thinking about the LRC problem it may not be so onerous if it is for a very short period of time that this is required....,ie more than the amount of time it takes for the pump to burn out. I will do some more digging.

I appreciate the help.

 

[Pete999]

There is a spec and drawings (layout only) but the spec says things like “supply to specialists requirements”, and the specialist isn’t committing to much.

Probably doesn't know whats what anyway

 

[marconi]

I think you may need to clarify how the pumps are to be operated ie:

1. Both running at the same time in which case you probably need a scheme for sequential starting one then the other.

2. Master and standby - one nominated to start first and the other only starts subject to some conditions such as perhaps low pressure or Master fails to start in which case standby auto-starts or has to be manually started .

You get the idea.

 

[JameZZZ]

I think you may need to clarify how the pumps are to be operated ie:

1. Both running at the same time in which case you probably need a scheme for sequential starting one then the other.

2. Master and standby - one nominated to start first and the other only starts subject to some conditions such as perhaps low pressure or Master fails to start in which case standby auto-starts or has to be manually started .

You get the idea.

Your right I will seek clarification.
I am pretty sure it is master standby. My concern is that they are asking for supply sized for both pump in LRC condition. I guess the main pump could lock and the standby could kick in then lock as well. Then the problem could clear and the supply would have failed before the pumps. As previously noted I will see if I can find out how long it takes for the pumps to burn out as long as the supply does not break in a shorter time than this I can’t see the point in sizing to LRC for a longer period. Thanks again for help.

 

[marconi]

Would you mind writing another post once you have squared away your questions? It adds to the wealth of knowledge of all of us and our interest - otherwise we are left hanging.

 

[westward10]

You are dealing with something which could be deemed a safety system. Get an experienced person to design it for you or pass it over. By safety system I mean peoples lives could rely on what you are installing.

 

[JameZZZ]

You are dealing with something which could be deemed a safety system. Get an experienced person to design it for you or pass it over. By safety system I mean peoples lives could rely on what you are installing.

Whilst I agree with this statement finding someone who does have experience and is willing to commit to anything is proving tricky..... do you know anyone?

 

[JameZZZ]

Update: I have found an excellent guide to this:

BSRIA BG 70/2017 Life Safety and Firefighting Power Supplies

I have not fully read it but it looks like it is going to give me guidance on all my questions.

 

[JameZZZ]

Would you mind writing another post once you have squared away your questions? It adds to the wealth of knowledge of all of us and our interest - otherwise we are left hanging.

Marconi,

Here is what I have found out:

The ATS needs to go by the pump control panels (this is pretty clear in BS9990). This makes sense in terms of better redundancy (2 sets of cables over diverse route). The mains monitoring for generator control should be at the ATS.

As you noted to design the supply you need input on worst case scenarios from the specialist (something I am pursuing). However in very general terms: The mains supply and the back supply need to be designed in accordance with: All the normal stuff you would associate with a motor (starting current, motor rating, efficiency, pf, , starting volt drop, FLC etc.), and the supply and cable must be able to take 150% of the FLC , and it must hold under LRC conditions for 1 pump for 75% of the time it takes for motor burn out. This Basically means appropriately sized BS88 fuses feeding FP600S cables on separate diverse routes feeding the ATS. The fuses need to discriminate with the specialists overloads in the pump starter (I am assuming the specialists overloads need to adhere to all the above as well so I am expecting my fuse and cable sizes to get quite big). Thanks for pointing me in the direction of BS9990. The document which really sorted it for me was BSRIA BG 70/2017 Life Safety and Firefighting Power Supplies.

 

[Bobster]

There may even not be any overloads in place within the starter.

 

[JameZZZ]

There may even not be any overloads in place within the starter.

That would make sense for a pump that you want to run to destruction. I have asked the question of the specialist, along with details of motor burn out time etc. He is going to ask his supplier. I will let you know the outcome if interested.