A common question I get when servicing gas systems is why do I have to hold down the pilot knob for so long for it to stay lit.
The answer is while you are holding down the pilot button it is heating up a part called a thermocouple that actually creates small amounts of electricity once heated.
The thermocouple creates a small amount of electricity that activates a safety magnet that holds open a valve that allows gas to continue to flow through the system. This is very important for safety because it shuts down the flow of gas in the event that the burner goes out and keeps gas from filling your house.
From a repair standpoint, if you depress the pilot for an extended amount of time and the pilot light does not stay on, you might have a bad thermocouple!
For safety, always have a NFI certified gas specialist perform any diagnosis and repair of your gas system and enjoy your fireplace this Winter 🙂