24v Fire Alarm Needs to Switch 240v shut off valve/Solenoid

[tazz]

Hopefully a diagram might help any 24v coiled relay with mains rated 10A contacts will do the job,

 

[robbo777]

View attachment 15921

Hopefully a diagram might help any 24v coiled relay with mains rated 10A contacts will do the job,

Perfect, thank you very much

 

[tino1888]

We wire this type if setup in all schools nowadays. Usually for boilerhouse, kitchens, classrooms. If you have a ventilation system ie: supply/ extract fans supplying the warehouse it may need coiled with a fan proven switch.

Failing that as previous post have said. Wire in a 24v relay, with 240v contacts..

There's a whole host of building control regulations regarding gas solenoids now.

Most units we fit/wire in the classrooms have a leak pressure switch on the gas solenoid as well. just in case the kids leave there Bunsen burners on

 

[Spoon]

Hi robbo77. As I asked in post 4, do you know what size the solenoid is? The 230V supply to it will need a fuse.

 

[Darkwood]

As engineer54 mentioned a relay is the way, very straight forward, you want a 240 volt relay with a 24 volt dc coil, when the bells ring the relay coil is energised and the supply to the gas valve is broken, how you energise the coil is a matter of a couple of ways, via an alarm relay in the panel or by a sounder itself, the latter not so good as you may need a diode doing it this way to ensure the panel doesnt go into fault.

This suggested set-up isn't fail safe assuming the alarm is acting on a real fire situation then as soon as this cable looses supply and/or is damaged by fire the solenoid will open again letting gas through, although im unsure of codes of practices here i feel its not as simple as it sounds, if op has a output relay then volts free then an external power supply with independant battery back-up should be holding the relay open and the failure of the independant supply or alarm activation will close the valve ... any fire damage or general damage to the cable will then see the valve close.

Its possible dependant on the alarm panel to use the internal 24v supply to eliminate the need for a external relay and power source but this will be dependant on the size of the solenoid and the 24v output max current rating.

As already mentioned it may be the case that safety relays or specific interface boards should be used and another issue is the reset and indication system the gas valve shouldn't re-energise automatically IMHO without a operator reset been applied but il reserve this judgement for now as resetting the panel could be classed as a operator reset, also a test function should be implemented into the design and if done and an over-ride as you dont want to loose the gas and have to prime all the boilers and burners everytime you do a test on the alarm although it should be subject to its own testing routine.

 

[Darkwood]

@ the OP ..... I suggest you wise up on fire alarm installation regs and i dont mean BS 7671, you need to purchase the relevant reg's, i would tread very carefully here as you could be putting yourself in a position of responsibilty if the system you fit fails, worse case lives could be lost and you need to proof the system you fitted was in full compliance with the relevent fire/safety regulations.

Im a little supprised at the ease of some members here to give many suggestions without considering they could be suggesting a system that falls far short of what is required, i believe tino1888 hit the preverbial nail on the head with his post #23 where as such hes the only one to warn of a whole host of regulations you may have to comply to.

My suggestion is Sub a Fire Alarm company in who will be knowledged in this area, if their are not its on their shoulders not yours.

 

[MDJ]

This suggested set-up isn't fail safe assuming the alarm is acting on a real fire situation then as soon as this cable looses supply and/or is damaged by fire the solenoid will open again letting gas through, although im unsure of codes of practices here i feel its not as simple as it sounds, if op has a output relay then volts free then an external power supply with independant battery back-up should be holding the relay open and the failure of the independant supply or alarm activation will close the valve ... any fire damage or general damage to the cable will then see the valve close.

Its possible dependant on the alarm panel to use the internal 24v supply to eliminate the need for a external relay and power source but this will be dependant on the size of the solenoid and the 24v output max current rating.

As already mentioned it may be the case that safety relays or specific interface boards should be used and another issue is the reset and indication system the gas valve shouldn't re-energise automatically IMHO without a operator reset been applied but il reserve this judgement for now as resetting the panel could be classed as a operator reset, also a test function should be implemented into the design and if done and an over-ride as you dont want to loose the gas and have to prime all the boilers and burners everytime you do a test on the alarm although it should be subject to its own testing routine.

your absolutely right fella on all points, the only thing I would actually add, is the first method fed from the fire relay in the panel wouldn't be an issue, the gas will not switch back on if the bells stop ringing by using the silence button, it would only switch back on if the panel was reset from alarm mode, and the alarm should never be reset unless everything checks out okay and the persons in the building in charge of this would know through training not to reset a system unless conformation it is safe to do so has been established.

 

[tazz]

The diagram i have drawn here is a stadard fail closed system as required by BS5839 part 1 (monitored control), if you take note on the wiring you can see the relay is energised. For any reason power is lost to the relay ie damaged cable the solenoid will close. In the event of a fire condition again the power is removed. Other methods of shutdown ie pressure will be down to the statury risk assessment undertaken, or local authority guidlines.

 

[MDJ]

a good diagram actually tazz, I have wired valves this way you have drawn many times hence my initial comment about the relay, cheers for the drawing bud.

 

[tino1888]

Sometimes a aux contact on solenoids are also added to indicate the position of the valve.

Wiring anything to do with Gas installations is always tricky.

I even had a call from my aunt tonight asking for a fcu for a new combi as the gas guy 'won't pass it'.. Even thou I know there will be no bonding, labelling, or electrical testing prior to me fitting a fcu.

 

[tazz]

This is where designers, Architecs and local authorities all sit down and make a specifications. Once all specialist proffessions are sing from the same hyme sheet we design the fire alarm and switch gear to suit, as you can appreciate, this is usually not off the shelf gear so has to be designed and all metal work, and control panels made to order.

 

[Les Macaulay]

I'm surprised a 20 year experienced spark is asking this. Get a hold of the fire alarm guy on site and hand him a sheet of paper and a pen. He will sketch the circuit in minutes. Write back to [email protected] for a diagram.
Cheers
Les (ex-F/E Lecturer)