1. Vault Zoning Issues

Tony explained that the purpose of the meeting was to agree the relationship between

a. the “fire-curtain”/air conditioning zones in the vault, by default 3 in number, and

the electrical distribution zones, by default 4 in number.

Since we plan to cut the electrical supply to equipment if any smoke is detected, the obvious question is whether or not we should divide the room into 4 zones, albeit at the cost of additional air conditioning equipment.

Overall, the conclusion was “no”. Although there would be some gain (in that, potentially, fewer systems will be powered off when smoke is detected), this does not outweigh the extra costs involved (8 air conditioning units would be required, not 6; although these would have a lower rating, the costs would be very similar). In particular, Denis Raffourt commented that, given the sensitivity of the detectors, any smoke in the room would soon be detected in all zones.
Careful consideration needs to be given to the power supply arrangements for the air conditioning units. If there is smoke in one zone and the air conditioning units in that zone are stopped, smoke may be pulled to other zones if the air conditioning units are left running.
Anne and Denis questioned whether or not the “critical computing infrastructure” should be located in the middle zone. It was recognised that this location minimises the overall length of network cables, but the middle zone is most open to contamination from smoke in adjacent zones.

2. Smoke Detection Equipment

It was agreed that Denis Raffourt would cost the following.

A high sensitivity smoke detection system to be installed at ceiling level in each “fire-curtain” zone. Any alarms from these systems will lead to the Fire Brigade being called.
A lower sensitivity system located at the air intake to the air conditioning units (recirculated air). Coincidence of alarms from this and the high-sensitivity system in a given zone will lead to power being cut for all computing equipment in the zone concerned.
A detection system for installation under the false floor. There was some doubt as to whether or not such a system would be needed. On the one hand, it could indicate to the fire brigade that the smoke source was under the false floor. However, the air-conditioning arrangements (with air being recirculated and blown up through the false floor) are such that any fire/smouldering under the false floor will trigger the other smoke detection systems.

3. AOB

Jukka Lindroos will cost a water detection system; sensors to be placed close to the air conditioning units.

Tony asked Anne and Jukka for a list of equipment that could, potentially, be provided by Portuguese companies as part of an in-kind contribution to the LHC Computing Grid Project.

4. Fire Safety Issues

Shortly after the meeting, Fabio Corsanego came with the results of various calculations on the Fire Prevention arrangements proposed. These calculations indicate that smoke curtains of 50cm together with smoke extraction capacity of 10m³/s will contain smoke from a fire with a power of up to 2,700kW within a given fire-curtain zone.
A fire with a power of 2,700kW is a relatively large fire. In a “medium development’ scenario (likely, but not certain), it would take 15 minutes for a small fire (initial flames) to develop into a fire of this size, more than ample time for the Fire Brigade to arrive. Additionally, cutting equipment power immediately smoke is detected reduces the risk that smouldering develops into an initial fire, further extending the acceptable delay before Fire Brigade intervention.
Overall, therefore, Fabio concludes that the fire protection measures for the vault are acceptable.