Servery Exhaust Hoods Interlocked with Gas Supply to Equipment 2

[michael333]

Hello All!

I have a design with three separate Type I exhaust hoods in a Servery for venting typical kitchen equipment which is Gas-Supplied. The make-up air/cooling for the Servery is provided from a rooftop vav unit. This is a Servery for a dining hall on a college campus. The exhaust fans, rooftop unit, vav boxes, are all tied into a newly installed DDC system.

The project is currently in the construction phase. I've been made aware by the mech. contractor of a clear requirement in the 2003 International Fuel Gas Code which basically states that the gas, supplied to the kitchen equipment, has to be interlocked with the exhaust hoods such that the gas can not be delivered to the equipment unless the exhaust hoods and supply air are on(2003 IFGC: 304.9.2; 503.3.4; 505.1.1). Stupid me missed this requirement in the design. The issue is that unless there is a separate gas connection for the pilot lights on each piece of equipment, the pilot lights will be shut off anytime the exhaust hoods are turned off. The only two ways I can see around this is to have a separate gas connection on the equipment to the pilots or have electronic ignition on the equipment? Even if it does have the electronic ignition, there is still the requirement for the gas to be shut off when the hoods are turned off. Is there a designer/engineer out there who has ran into this problem before on their project? If so, any suggestions/recommendations? Also, when the IFGC says "interlocked", does this mean physically interlocked, or can I interlock the exhaust fans with 2-position solenoid(maintain contact) valves to shut-off gas to kitchen equipment through the DDC system?? Would the code allow this route? Or this a question for the AHJ?

Any help in this matter would be greatly appreciated!

 

[NCDesign]

Someone feel free to correct me but I don't think your interpretation is quite right. I think the code sections you are referencing apply to mechanically providing the required combustion air or a fan required for the exhaust of the products of combustion. Think power venter for a boiler. The kitchen make-up and exhaust fans are for the kitchen hoods and not for combustion air or the products of combustion.

The requirement I think you should really be concerned with is the safety interlock with the fire suppression system in the hoods. Activation of the fire suppression system should shut-off the make-up air fan and kill the gas supply to the appliances, including the pilot lights. The exhaust fan should still run. Unfortunately I don't have the full building code & fire code at my finger tips. Check out the IMC sections 506, 507, and 509. In this case the solenoid interlock you mentioned is the way to go.

 

[AbbyNormal]

If they are standing pilot, why can't the interlock be open contacts to the main gas valve?

Take the "V" out of HVAC and you are left with a HAC(k) job.