How to set threshold for my flame sensor?

Hello, I'm trying to build a basic flame sensor and used silicon carbide photodetector and a trans-impedance amplifier as a part of my circuit and trying to interface it with my arduino to detect the presence of flame or not. I have no idea about setting a particular threshold value beyond which it can detect the presence of flame without giving false alarm. Kindly share your thoughts as it will be very helpful.
A couple of thoughts. One, are you building a flame sensor or a flame detector? By flame sensor I am referring to something that senses a flame--such as from a fire burning hydrocarbons in a compartment where there shouldn't be any leaking hydrocarbons or fire? Or are you building a flame detector--something that will be used to detect the presence of UV flame in an area where hydrocarbons are being burned to produce heat (such as a boiler or gas turbine combustor)? I believe there are different "intensity" settings (threshholds) for the two types of devices (flame sensor versus flame detector)?

Second, I would think that by looking at the data sheets for similar industrial devices (flame sensors or flame detectors) you should be able to gain an idea of how the manufacturer programs them to sense fire or flame and produce a signal. Or, they might provide a sensitivity value that a user could choose based on the application (flame sensor or flame detector, for example).

Manufacturer's data sheets can very often have a LOT of information on them.

Hope this helps!