The International Fire Code (IFC) Section 6004 for highly toxic and toxic gases states the following for exhausted enclosures:

6004.1.3(1) The average ventilation velocity at the face of the enclosure shall not be less than 200 feet per minute with not less than 150 feet per minute.

However, in the same section for gas cabinets (Section 6004.1.2(1)), the words "at any point of the access port or window" are added after "150 feet per minute."

Doe anyone know if this was an oversight by the authors of this section? Did they miss a few words in the requirement for exhausted enclosures?

I don't understand why the 150 feet per minute would be for gas cabinets but not exhausted enclosures (albeit without referencing where the 150 feet per minute measurement is to be taken). This issue is coming up at my work as we have several exhausted enclosures and gas cabinets and some of the exhausted enclosures have ports/windows which are sealed shut. Thanks in advance!

​​​​​​​​​​​​​Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe

​Determine the visibility (in meters) for a light reflecting exit sign with smoke that is produced by pyrolysis of plastic. Assume the smoke has a mass concentration of 0.09 grams per cubic meter.
a. 4.4 m
b. 7.6 m
c. 11.7 m
d. 20.2 m

Solution | Posted 09/29/20

An existing F1 occupancy with no high-piled storage is getting an addition, resulting in the total square footage for the entire F-1 area (all open) being over 50,000 ft sq, thus requiring smoke and heat vents per the 2012 IBC and IFC.

The question was asked if smoke and heat vents can just be added to the new addition and install a draft curtain to separate the existing from new, so smoke and heat vents will not be required in the existing space.

My question is, would a draft curtain be sufficient for creating a divided area in this regard?

There is no true definition of a divided area in either the building or fire codes. I wouldn’t think it would necessarily need to have a fire barrier or partition. I would assume a properly sized trap curtain would be sufficient?

Does anybody have any experience with this unique type of issue, or have any comments or suggestions?

​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

A stair is being designed as pressurized as part of a smoke control plan. A single door gap below a 4 foot wide door has a 0.35 inch tall door gap where the pressure differential between the two sides of the door are 0.1 in. w.g.. Assuming a flow coefficient of 0.7 and normal atmospheric conditions, what is the volumetric flow rate of air through the gap?
     a. 33 cfm
     b. 73 cfm
     c. 104 cfm
     d. 148 cfm

Solution | Posted 07/21/20

We have an auditorium with a stage area. The stage area is fully sprinklered and provided with four natural smoke vents at the roof.

Below the smoke vents at a depth of almost 10-feet (3 meters) there is structural steel frame (provided for structural stability) arranged with narrow gap of only about 1-inch (30 mm) and obstructing all the smoke vents. We understand this steel frames will deflect the smoke plume and affect the performance of smoke vents.

Is there a standard/code reference regarding how to include this obstruction in the calculations and to prove to AHJ that the smoke vents would still be sufficient?

Thanks in advance.

​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

This building is an H-1 occupancy. There is an area of refuge on the 4th floor. The shelter-in-place Class 3 area of refuge is protected from interior and exterior hazards. There are vertical openings through all 4 floors. The UFC is governing.

Based on this, do the stairwells need to be intertied directly to the shelter-in-place area of refuge for an exit enclosure that is a direct accessible means of egress (we are providing accessibility provisions)? Does the shelter-in-place area need to be a smoke enclosure as well as the interconnected stairwell system?

Based on this will both the stairwell and the shelter-in-place need to be pressurized to meet design intent?

Both exterior and interior air is hazardous and a scrubber would be needed to inject air for stairwell pressurization.

​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Being told I need two fire dampers to serve a single fire wall. The fire wall is made of a "double wall", essentially two masonry walls next to each other with a very small (less than 2-inch) air gap in-between. The engineer on the project is stating that this "double wall" requires a fire damper in each.

I've never come across this as a requirement before. Do I need two fire dampers?

​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

We have a project where a control module is connected to the mechanical controls that is programmed to the variable frequency drive for a fan on a large unit. When a duct detector senses smoke, the control module (which is normally-open circuit) will close the circuit, sending a signal to the mechanical controls which shuts down the unit.

On this project we had a bad set of control modules that didn't work. We discovered this in testing with the local jurisdiction, and swapped out the modules and the system now works correctly. 

Both the jurisdiction and I wondered whether this normally-open arrangement is acceptable. If a control module were to fail, the duct detector would not be able to close the circuit on the module and the fan would remain running. In this scenario, there would be no supervision or way to know that the control module failed other than someone standing at the fan or finding the issue during testing.

My inclination is that in the future these modules could be normally-closed and open upon duct detection. That way if the module fails and opens on its own, the unit will shutdown in a "failure" mode.

Is it code required that this arrangement be fail-safe?

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Have a project that requires the sprinkler system to be zoned by the areas with active smoke control. Each floor of the highrise is approximately 12,000 sqft is to be divided into two zones. I intend to have multiple floor control risers (valve, check valve, flow switch, pressure gauge, inspector's test & drain) for each smoke control zone. Is there any less costly way of accomplishing this?

It has been suggested that multiple flow switches can be placed on the same system with different retard settings so that the fire alarm system can identify where the water is flowing, but I don't have experience with this option.

Posted anonymously by a member for discussion. Discuss this | Subscribe.