SFPE Discussions

Platforms in Packhouses

Good morning,

In many packhouses there are conveyors that bring the fruit in and there are walkways for supervisors and usually small control rooms elevated around 1500mm above the floor and above the conveyor. Not exactly “intermittent” use, but certainly low occupancy (<4). Control rooms are entirely glass walled.

Is this an “intermediate floor”. If so it required fire ratting to the underside along with the underside of the walkway that leads from it. BCA says it is an intermediate floor and C/AS2 4.13.9 does not apply.

Are they correct?

Technically, yes - because its not intermittent use. So perhaps rather trying to use C/AS2 it needs to be an alternative solution with request for modification for that clause?

In regards to what is intermittent use, the objective of the allowance is to recognize the risk. The risk to a person on the intermediate floor or plant platform is a function of time. The control room is not intermittent use as it is occupied during packing season for say 8-12 hours per day for 7 days over week for several weeks. The HVAC plantroom is occupied for say 15 minutes once a month, so the chances of something happening when the HVAC platform is occupied is ~1000 times less. It is the same reasoning that we don’t protect access across a roof leading to a roof plant platform, where we would if it was the escape route from say an office.

I would look at what you are trying to achieve here.
What is the rationale behind all the intermediate floor requirements? Two main culprits spring to mind:

  • fire from below, and
  • smoke from above.

Smoke from above
Intermediate floors pose a greater risk to occupants because the smoke plume can generate a smoke layer that could engulf the occupants much faster than if they were at ground level - intermediate floor occupants generally are escaping in the “hot layer” for a short period of time.
If your packing shed is a high roofed space, then the 1.5 m platform would be of no consequence and should not be considered as an intermediate floor in the context of smoke layer tenability.

Fire from below
Fire rating the floor and walkway should be a consideration based on potential fire load under and ignition sources. As Geoff has already stated the likelihood of occupation of the space is high.
For me, the threat is fire from below; not smoke from above. Unless you can physically prevent a fire load and ignition source beneath the elevated structures, fire rating the floors would be a really good idea.

I understand where you are coming from but, due to automation, the control room is not occupied 100% of the time. Maybe two people 50% of the time. It is 1.5 metres above the ground with glazing all round. The primary risk is a fire occurring directly beneath the room. It could conceivably be enclosed beneath. So thanks for the feedback, it does help. But…when does an intermediate floor become an intermediate floor? Is a stage in a hall an intermediate floor for example?

Hi Tim
Have these people never heard of CCTV? The sole reason for an elevated glass walled control room is to allow the operators to observe the plant. Install CCTV, and put the control room at ground level.