All Detectors will be Tested on site with the Smoke  Detector Tester.
This is  the same method applied to Fire inspection by SCDF

There's Smoke There's Fire
Prevention Is Better Than Cure

Before it is too Late
***All smoke detectors are tested with Smoke Detector Tester before it is delivered to the customer.***
Smoke Detector is a very useful Gadget
while you are working, answering phone call when you are doing your cooking with open flame.. 
and Give you a Peace of Mind While you are in deep sleep at night.. Zzzzz