What's the Maximum Area 1 Smoke Detector Can Cover?

There are many, many more factors to consider in addition to elevation above finish floor.

Excerpted from the NFPA website:

"NFPA 72 covers the application, installation, location, performance, inspection, testing, and maintenance of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire warning equipment and emergency communications systems (ECS), and their components. 1.1.2 The provisions of this chapter apply throughout the Code unless otherwise noted."

This guides the USA. In addition, localities have the power to make the regulations more strict. Wherever you are at will have something similar.

Coverage would vary depending on a myriad of factors. So, it's impossible to answer the question.

Since this is personal safety issue you MUST get a local opinion. Someone's life may depend on your selection of equipment and it's installation.

HIRE an expert!!!!!!!!!!!!!!!!!!!!

i think you some point their but the beam of photo electric detector the reach of it is the area it could covered. and that is why i am asking about radial area because of the beam radius. how long it could reach. our contractor before told but maybe he talking only about the brand he is selling. i am asking this question so taht ic ould istimate the quantity roughly of what we need..

thanks to uall guys. i do hope one day i can contribute here too

Now, wait a minute...

Are you now talking about a projected beam smoke detector? This sort of thing:

http://www.systemsensor.com/pdf/A05-0217.pdf

These type of things can monitor about 100 meter distance... not necessarily a 100m semicircle... footprint coverage varies, but a pretty large area.

You've gotten some sound practical advice here. Consulting the NFPA standard will give you PART of a definitive answer. However, in the front of each standard is a disclaimer that authorizes the AHJ (Authority Having Juridiction) to alter the requirements of the standard (as long as they are more stringent). The AHJ is typically the Fire Marshal for the locale. The responder who stated that "placement" is the more important factor was spot on. That placement is going to depend on many factors. The Fire Marshal or Building Inspector would be an excellent source of information.

Try the relevant products datasheet

What's the Maximum Area 1 Smoke Detector Can Cover?

1oometer sq. feet