type I hoods

[Just John]

NFPA 96 2011 edition section 8.3.2 states under the heading of replacement air, "When the fire-extinguishing system activates, makeup air supplied internally to a hood shall be shut off." 2009 IFC does not refer you to NFPA 96.

If you have not adopted 96 do you just go with both exhaust and replacement air have to stay on if hood system trips, according to our mechanical inspector, or is there usually something in the manufacturers instructions that addresses this?

 

[cda]

you would have to check each manufaturer

Most of the time I see the extinguishing companies shuting down the make up

IFC 904.3.3 says it indirectly

"""""I would post the section but on 24 hour black out, because of the proposed Sopailla legislation"""""

 

[Builder Bob]

It is funny that the IFC doesn't use NFPA 96, however, the FM or UL standard uses or addresses NFPA 96 as the standard to which hood assemblies are tested by............. In other words, the way to find that anser is to look at the installation guide for proper operation sequence operation -

 

[BSSTG]

Greetings,

I've talked with a number of fire systems installers the last couple of years about this and from what I can gather the jurisdictions in our area are divided roughly half and half. It makes sense to me that you want to cut off the oxygen supply but on the other hand if the fire is way up in a long hood you would want the air flow to carry the extinguishing chemical up to the fire. I personally have never seen really long ducts for the Type I hoods though.

BS

 

[cda]

yea kind of right

shut down the make up

keep the exhaust running, but not a requirement

 

[mtlogcabin]

NFPA 96 Section 10.2.6

Automatic fire extinquishing systems shall be installed in accordance with the terms of their listing, the manufacture's instructions, and the following standards where applicable:

1 NFPA 12

2 NFPA 13

3 NFPA 17

4 NFPA 17A

The ICC covered this in the IFC

904.11 Commercial cooking systems.

The automatic fire-extinguishing system for commercial cooking systems shall be of a type recognized for protection of commercial cooking equipment and exhaust systems of the type and arrangement protected. Preengineered automatic dry- and wet-chemical extinguishing systems shall be tested in accordance with UL 300 and listed and labeled for the intended application. Other types of automatic fire-extinguishing systems shall be listed and labeled for specific use as protection for commercial cooking operations. The system shall be installed in accordance with this code, its listing and the manufacturer's installation instructions. Automatic fire-extinguishing systems of the following types shall be installed in accordance with the referenced standard indicated, as follows:

1. Carbon dioxide extinguishing systems, NFPA 12.

2. Automatic sprinkler systems , NFPA 13.

3. Foam-water sprinkler system or foam-water spray systems, NFPA 16.

4. Dry-chemical extinguishing systems, NFPA 17.

5. Wet-chemical extinguishing systems, NFPA 17A.

Exception: Factory-built commercial cooking recirculating systems that are tested in accordance with UL 710B and listed , labeled and installed in accordance with Section 304.1 of the International Mechanical Code .

and

904.11.3 Carbon dioxide systems.

When carbon dioxide systems are used, there shall be a nozzle at the top of the ventilating duct. Additional nozzles that are symmetrically arranged to give uniform distribution shall be installed within vertical ducts exceeding 20 feet (6096 mm) and horizontal ducts exceeding 50 feet (15 240 mm). Dampers shall be installed at either the top or the bottom of the duct and shall be arranged to operate automatically upon activation of the fire-extinguishing system. When the damper is installed at the top of the duct, the top nozzle shall be immediately below the damper. Automatic carbon dioxide fire-extinguishing systems shall be sufficiently sized to protect all hazards venting through a common duct simultaneously.

904.11.3.1 Ventilation system.

Commercial-type cooking equipment protected by an automatic carbon dioxide extinguishing system shall be arranged to shut off the ventilation system upon activation.

It will depend on the system installed

 

[Codegeek]

The 2012 IMC references NFPA 96.

 

[FM William Burns]

The reference to the 2008 NFPA 96 does not allow one to shut down make up air and one whould have thought the IMC (502) or IFC (904.11.2) would have included it. They (including NFPA 96) should make reference to multiple story exhaust duct with calculated make up flow allowances. Well I guess if they can't figure out where HVAC duct detectors should go this won't get resolved in my career either

BTW....NFPA has had the make up shut down since early 90's (as an exxception) if I recall correctly.

 

[Codegeek]

The reference to the 2008 NFPA 96 does not allow one to shut down make up air and one whould have thought the IMC (502) or IFC (904.11.2) would have included it. They (including NFPA 96) should make reference to multiple story exhaust duct with calculated make up flow allowances. Well I guess if they can't figure out where HVAC duct detectors should go this won't get resolved in my career either BTW....NFPA has had the make up shut down since early 90's (as an exxception) if I recall correctly.

Sorry, my bad on the reference. The OP mentioned it wasn't referenced. I totally agree on the duct detectors.

 

[IJHumberson]

Keep in mind, though, the requirement for shut-down of make-up air only applies when the m/u air is "supplied internally to a hood" - I've not seen very many hood/duct systems that the make up air supplies internally to the hood - it usually is fed external to the hood and near the top of the hood.

 

[FM William Burns]

Just got back from two retro installs of new suppression systems on existing type I's at a Wendy's. Both have m/u air being served internally and thankfully both shut down upon activation. Just wish I didn't wear my white shirt there.....really must recommend quarterly cleaning

 

[fireguy]

on .....really must recommend quarterly cleaning

Paraphrased from NFPA 96-2008 (my 2011 is in the van)

11.4 entire system to be inpected for grease build up by a properly trained, qualified certified person, in accordance w/Table 11.4

Table 11.4 Quarterly inspections required for high volumn operations such as 24 hour cooking, charbroiling or wok.

Charbroilers in BK and DQ do need quarterly cleaning, especially the BK with a Gaylord hood. Some need cleaning more often. Most chinese need to be cleaned every other month. Good luck on that.

Look at figure A.11.6.2 for a gauge than can be used to determine when the grease needs to be cleaned.

Grease fire are impressive!

 

[FM William Burns]

FG,

I'm with you there on the exhaust system and my 2001 T-11.3 says the same. I should have clairified the actual cooking equipment and fryer sides and rear. I'm a hands on FM and if I like the firm I'm working with or there to inspect, I'll help the Tech. move some equipment and that's where my white shirt got messed up. It did however give me the opportunity to show the management why they needed better housekeeping practices when I showed them the outlets and greese build up....scary. Follow up in 10 days

 

[AegisFPE]

I agree with Humberson, that NFPA 96 only requires shutdown for "internally supplied" mua. However, it would seem that this would not preclude stopping externally supplied mua, though such action should not be required. But keep the exhaust going! (Had a project recently where all airflow was to stop; we got them turned around).