It's a bit more complicated, but not a lot.
When the cable is pulled and the micro switches are tripped:
Gas valve, electric fryers, and make up air must shut off.
Exhaust hood must turn (or remain) on.
Sometimes they want the lights off also. Not in my area.
Shunt trip breakers make sense in some situations. The 120V micro switches make sense on most things. The units I've installed had two or three (each) NO and NC contacts right at the ansul supply trigger.
Gah! That was for the OP
Mag.
Do I need a disconnect switch beneath this unit?
No
Can I have a separate switch to operate the lights inside the hood?
The lights generally have a separate switch for normal operation. They may or may not be required to be disconected when the system is activated.
That is the exact system I hooked a while back.
Tell us exactly what equipment is under the hood and if the lights are required to be shut off. The rest is cake.
Put a short piece of conduit/flex on the pigtails and terminate everything in a 4S box. Run some conduit/flex from the ex fan/mua switch (possibly the lights) and another to the gas valve (if applicable)
You have two (white) commons, two NO's and two NC's. The NO, NC thing confused me with the "held open/closed" thing. Determine if the system is cocked, and ring them out to be sure. Usually they don't activate them until all the testing has been done.
Run the exhaust fan switch leg (from the
line side) thru a NO contact. In case of fire, you want to vent the building even if the switch is turned off.
Run the make up air switch leg (from load side) thru a NC contact. In case of a fire, the last thing you want is fresh air being pumped in.
I believe the gas valve will be a NC type so power it (to open it) via a NC contact. There is not much amperage so it can be powered off the ex fan/mua circuit.
If there are any shunt trip reakers involved, I believe they activate/tripped by the 120 power. If so, they will go on a NO contact.