The most suitable type of smoke alarm for freight vehicles is JTY- gd-dg312.

JTY GD - DG312 smoke alarm for freight vehicles with high sensitivity, stable and reliable, low power consumption, beautiful and durable, convenient use, etc, in use process can better protect the safety of the freight car, is is the first selection of smoke alarm is described in detail below:
Installation and debugging
(1) make four dates on the wall according to the installation size.
Fixed hole of 6mm;
(2) insert the expansion plug into the fixed hole and screw in.
Self-tapping screw, reserved about 2-3mm gap;
(3) the detector connects the power cord and the signal line first.
The remaining signals can be cut off according to actual requirements;
Two connection mode
Red line -- -dc +.
Black wire --DC-.
Connect DC9-DC46V power supply;
White line NC- relay signal normally closed contact;
White line COM- relay signal common end contact.
3. Instructions
Normal state: detector starts 2HZ 5 relay.
Close/open, probe into working state.
Self-check status: the detector should be self-checked periodically, when pressed.
When the key is pressed, the output contact of the detector relay is closed;
After releasing the key, the detector automatically returns to normal work.
As a state.