Fire suppression control

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Joe13789

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Hi all,

I’m working on a residential kitchen, and for whatever reason the owner has decided to install a fire suppression system. So, I now need to make it control various things in the kitchen.

1. Hood light needs to turn off
2. An outlet behind the stove needs to turn off
3. Electric gas shut off needs to activate
4. Exhaust fan needs to turn on
5. Makeup air needs to turn off

And, this system needs to be connected to the main fire panel for the building. Right now, it’s a box in the kitchen with 6 wires coming out - 2 red, 2 black, and 2 brown.

My understanding is that it’s a double microswitch, and those wires are the N/O and N/C, and a common wire. Here’s a picture. http://imgur.com/HEJKme7

So, can I use a 3 pole contactor to control the 3 items that need to get turned off, and a single pole contactor to control the exhaust so that it turns on? I think I understand what needs to happen, it’s the actual “how do I make that happen” where I get a little lost.

Thanks!
 
I've wired plenty of there systems, including that control head. Questions:

1. Tell me the fan switching arrangements: one switch for both, or separate intake and exhaust?
2. 120v motors, or contactors for 208v or 240v 1ph or 3ph motors?
3. They want "night mode" where heat causes exhaust turn on w/10-minute operation?
4. Is there a gas-valve reset box that must be set after turning on the exhaust?
5. Standing pilot lights or electronic ignition?
6. Local horn/strobe, or building alarm only?
7. Details about appliance receptacle?
 
To answer your questions:

1. Seperate switches for makeup air/exhaust
2. 120v motors
3. They haven’t said anything about night mode, and the hood doesn’t seem to have a t-stat
4. I don’t believe there is a gas valve reset. It looks like it’s basically wired like a light, if power goes to it then it activates and closes. (Currently it’s not connected and gas is flowing.)
5. Electric ignition
6. Building alarm only
7. Appliance receptacle is a standard 120 outlet
 
I made this just now. If it doesn't suit, such as one circuit can't run both motors, let me know.:

FS1.jpg

From your pic, it appears the red wire is the common terminal (C), the brown is the normally-closed (N), and the black is the normally-open (E).

EX = exhaust fan motor
IN = make-up air motor
L = under-hood light(s)
G = gas valve solenoid
C = receptacle contactor

C = micro-switch common
N = normally closed (when system set)
E = normally open (closes when tripped)

Building alarm connects to C and E of second micro-switch; cap (or remove) unused (brown) wire.
 
LarryFine said:
I've wired plenty of there systems, including that control head. Questions:

1. Tell me the fan switching arrangements: one switch for both, or separate intake and exhaust?
2. 120v motors, or contactors for 208v or 240v 1ph or 3ph motors?
3. They want "night mode" where heat causes exhaust turn on w/10-minute operation?
4. Is there a gas-valve reset box that must be set after turning on the exhaust?
5. Standing pilot lights or electronic ignition?
6. Local horn/strobe, or building alarm only?
7. Details about appliance receptacle?
Click to expand...

The majority of small systems use a cable operated gas valve, not a solenoid one.
 
gadfly56 said:
The majority of small systems use a cable operated gas valve, not a solenoid one.
Click to expand...
With recent rule changes (here, at least), the systems with cable-operated valves must also have thermostatic sensing that triggers the exhaust fan to operate upon reaching 100 degrees in the hood or duct, and for 10 minutes after the under-hood temperature drops back below 100.

This is because the exhaust does not have to be on for the gas to flow. The owners of kitchens with standing-pilot ignitions prefer adding this operation to having to light pilots every day.
 
LarryFine said:
With recent rule changes (here, at least), the systems with cable-operated valves must also have thermostatic sensing that triggers the exhaust fan to operate upon reaching 100 degrees in the hood or duct, and for 10 minutes after the under-hood temperature drops back below 100.

This is because the exhaust does not have to be on for the gas to flow. The owners of kitchens with standing-pilot ignitions prefer adding this operation to having to light pilots every day.
Click to expand...

The 10-minute rule is new to me. Is that a local/state thing or did they change something in NFPA 96 or NFPA 17A?
 
gadfly56 said:
The 10-minute rule is new to me. Is that a local/state thing or did they change something in NFPA 96 or NFPA 17A?
Click to expand...
I only know what the fire-protection company that either hires or recommends me tells me:

Upon system trip:

Exhaust must turn or stay on
Make-up air must turn or stay off
Gas must stop, not resettable
All appliances must lose power
Lights (usually) must turn off
Horn/strobe or building alarm
Night mode if mechanical valve
 
RICK NAPIER said:
It's 15 minutes and it is found in the International Mechanical Code (IMC) 507.1.1
Click to expand...

Rick, that's the turn on time, not the coast down time.

Where one or more temperature or radiant energy sensors are used to
activate a Type I hood exhaust fan, the fan shall activate not more than 15 minutes after the
first appliance served by that hood has been turned on.
 
gadfly56 said:
Rick, that's the turn on time, not the coast down time.

Where one or more temperature or radiant energy sensors are used to
activate a Type I hood exhaust fan, the fan shall activate not more than 15 minutes after the
first appliance served by that hood has been turned on.
Click to expand...

If you have a manual cable operated gas valve, and a commercial stove with a standing pilot, two or more burner, how do you get a signal when the first appliance was turned on?

Do you rely on the heat detector and its placement to give a signal, within the 15 minutes?

I have a hard time seeing one burner activate the temp sensor's, in a long commercial hood with say 2 or three fans.

A calibrated flow switch on the main gas supply?

I often see prep cooks, turn on one or two burners to heat things, without the fan running, especially in winter. How do you make the system compliant, if the fire contractor only supplies a heat detector?
the fan shall activate not more than 15 minutes after the
first appliance served by that hood has been turned on.
Click to expand...

MTW
 
MTW said:
Do you rely on the heat detector and its placement to give a signal, within the 15 minutes?

I have a hard time seeing one burner activate the temp sensor's, in a long commercial hood with say 2 or three fans.
Click to expand...
I've tried it myself. The exhaust fan(s) usually turn on within five minutes.
 
What type heat detector does your contractor supply, a fixed temp or a rate of rise detector. And do they supply multiple multiples for a long hood?

MTW
 
MTW said:
What type heat detector does your contractor supply, a fixed temp or a rate of rise detector. And do they supply multiple multiples for a long hood?

MTW
Click to expand...

Use a Fenwal "finger" detector. They're pretty responsive, come in stainless steel, and are rugged as all get out. They go in the duct opening, maybe a foot up or so, and you'll need one for each duct if it's a long enough hood.
 
Fenwal Detect A Fire

Fenwal Detect A Fire

I have used them many times. But never heard them called a "finger detector" before.

IMG Fenwal Dect-A-Fire.jpg

Mounted inside the duct, up a foot I could see that as a good placement for use as an initiating device.

But for detecting one burner "turned on" in a long hood, within 15 minutes? I would think that you would want it mounted in the top of the hood, near the manual burner.

What say you Larry? Hood mounted or duct? Do you know what temp calibration your fire contractor supplies?

MTW
 
MTW said:
What say you Larry? Hood mounted or duct? Do you know what temp calibration your fire contractor supplies?
Click to expand...
I've installed them both in the hood above the grease catchers and in the duct within one foot of leaving the hood.

I remember them being set respond when they reach 100F. A supplied timer module assures the 10-minute run-time.

I believe the timer also makes the exact location in the hood less important for the effects of exhaust air movement.
 
MTW said:
I have used them many times. But never heard them called a "finger detector" before.

View attachment 22685

Mounted inside the duct, up a foot I could see that as a good placement for use as an initiating device.

But for detecting one burner "turned on" in a long hood, within 15 minutes? I would think that you would want it mounted in the top of the hood, near the manual burner.

What say you Larry? Hood mounted or duct? Do you know what temp calibration your fire contractor supplies?

MTW
Click to expand...

If you set them in the duct, any natural draft will pull the heated air right past the detector.
 
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