Sorry Dan but the 1992on carb modles had a charcoal canister. There was no purge valve, but there was a thermostatic vacuum valve fitted into the thermostat housing which provided a similar function. The ECU controled electric purge valve replaced this on the injection cars.'Certain conditions' pretty much means only when the engine is in high speed over-run and at proper operating temperature. It will open at some other times but that's basically it.
Slimer, the canister is actually under the offside wing!!!
...and only on injection cars. If you don't have injection you shouldn't have one so don't worry about it.
1992 being a year when many stringent emmissions legislation were introduced