Smoke detection on aircraft

[Capt Ted Striker]

Reference the recent post on the tragic Swissair accident. Can any tecchies enlighten on the smoke detection systems on modern large aircraft. Why is it not apparently possible to "vent" (at least the cockpit) when smoke enters the cabin. The effects of smoke in the cockpit far outweigh any additional risk of "feeding" the fire. Electrical fires can produce very high levels of smoke compared to their actual fire risk. I remember when planning fire detection for computer suites many years ago, smoke sampling was a technique used. This is where, due to the need for very rapid detection, small aroured tubes were led from critical areas to a "sampling" chamber and at the first minute whiff of combustion, alarms were activated and extinguishers discharged locally.I realise that this may not be totally practical in the aircraft situation.
Anybody "up" on a/c fire systems?

[woftam]

Capt Ted Striker,this doesn't quite answer your question but you reminded me of something that may be useful, particularly to drivers of older A/C.
Many older A/C have a sextant mount valve in the roof of the cockpit.If you're A/C has one of these know how to use it and experiment with say some cigarette smoke.
It is a VERY effective way of clearing smoke from a cockpit and it also reveals the source/location of smoke for isolation purposes.It is also very easy to control the rate of the flow.
It is something I stumbled onto many moons ago and I pass it on in case you or anyone reading this is flying a "museum piece" with said apparatus.
You can also attach a hose to it and vacuum the cockpit. True!! I don't recommend it (vacuuming) on A/C like B727 however due to engine ingestion problems.
Cheers.

[easyout]

Striker, Modern aircraft do have smoke detector systems in the cargo holds, main avoinics bay and pax toilets.

The cargo bays smoke detectors have multiple sampling points and fire extinguishing capabilities.
The main avionics bay, smoke detection, consists of sampling the airflow used to cool the electronic equipment. This area usually does have the facility to quickly evacuate any smoke via a vent system overboard, but no fire extinguishing system

Apart from using dv windows I can't think of any modern aircraft that has a cockpit air vent system.

[gaterbait]

capt ted, about 12 yrs back i installed main cabin smoke detector systems in 3 or 4 dc 8 cargo acft.the system consisted of 4 zones, each zone having a sampling box & 5 inlets.the boxes & one inlet were inst'ld in the cabin ceiling with 4 inlet tubes running down the sides of the cabin to about shoulder height. cabin press air enteres the inlets, passing thru the boxes, & venting overboard. if smoke passed thru the boxes it triggered a light in the cockpit. pressurization loss was acceptable, as the tubing only 3/8ths inch dia.hope this is helpful. gb