Under GB 7258-2017 and JT/T 1178.2, what special design requirement applies to the exhaust tailpipe system of vehicles transporting flammable and explosive dangerous goods (Classes 1, 2.1, 3)?

1. The exhaust pipe must be installed at the front of the vehicle or directed downwards/sideways away from cargo, and equipped with a certified exhaust spark arrestor (排气火花熄灭器)
2. The exhaust pipe must pass directly through the middle of the cargo tank to preheat the chemicals
3. The exhaust pipe must terminate inside the driver's cab to allow continuous sensory monitoring of engine emissions
4. The vehicle must operate with the exhaust pipe completely blocked and sealed during transit