Let's look at the definitions: Ordinary hazard (Group 1) occupancies shall be defined as occupancies or portions of other occupancies where combustibility is low, quantity of combustibles is moderate, stockpiles of combustibles do not exceed 8 ft (2.4 m), and fires with moderate rates of heat release are expected. Dedicated and miscellaneous storage shall be protected in accordance with Chapter 12 and Chapter 13 as applicable.
Ordinary hazard (Group 2) occupancies shall be defined as occupancies or portions of other occupancies where the quantity and combustibility of contents are moderate to high, where stockpiles of contents with moderate rates of heat release do not exceed 12 ft (3.66 m) and stockpiles of contents with high rates of heat release do not exceed 8 ft (2.4 m). Dedicated and miscellaneous storage shall be protected in accordance with Chapter 12 and Chapter 13 as applicable. So based on what you've described, it would seem reasonable that for the assembly part that OH1 should be sufficient based on the NFPA 13 definition. Welding is not always considered a hazardous operation and can actually be performed in an F-2 occupancy where no sprinklers are present. There is some debate amongst those interpreting the Codes in what is considered F-1 "Metals" or Machinery" versus F-2 "Metal Products (fabrication and assembly) as defined in the Building Code. I wish there had been a little more detail given than just saying "Metals" because I've had this debate far too many times. So welding in and of itself is not a primary fire hazard in a controlled environment with procedural safeguards in place. Robotic welding is typically even safer than torch welding. Laser cutting about the same. The tractor-trailer in the building does pose a concern in regards to OH-1. On various projects I've considered the area as being a OH-2 as minimum criteria based on similar nature to loading dock areas which NFPA 13 does address. If the materials being stored are plastics or other flammable/combustibles or there are racks then the protection criteria is adjusted accordingly. But nothing less than OH-2 for loading areas with or without the truck. This has proven acceptable to various AHJ's and Underwriters. So it sounds like there may need to be some additional investigation and verification of design criteria for this area. Understand that NFPA 13 does provide OH-2 as the design criteria for machine shops and metal working so the AHJ may be looking at that alone as the criteria. However they should look at the OH definitions and then determine the most appropriate design criteria based on that, not just a catch-all description of an occupancy. Machine shops may or may not be OH-2 based on the metals being handled and the machining operation. A specific analysis needs to be done. The term "Metal Working" is vague and can encompass many different types of processes. The EOR should qualify their design by providing definition of the inherent hazards present in order to assist reviewers with verifying the design criteria as being applicable. Understand that without actually seeing the layout of the facility, how processes are separated and executed and understanding the owner's safety procedures, OH-1 may not be applicable and OH-2 may be right. The EOR should be the one to provide the information needed to defend Oh-1, not you and the AHJ reviewer should stipulate why they think OH-2 is more appropriate. Craig L. Prahl, CET Fire Protection CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of jd gamble Sent: Tuesday, March 29, 2011 11:48 AM To: [email protected] Subject: Re: Light Manufacturing Classification The facility incorporates a laser cutting machine for metal enclosure fabrication. Materials are primarily metal with limited plastics (less than 3%) and electrical circuit boards. Products are staged on wood pallets, single tier, no rack storage. Motors, vacuum pumps, electrical controls are manufactured by others and assembled in the facility. Plant operations include assembly, fabrication (including welding and laser metal cutting), and shipping (which has temporary staging of semi-tractor w/ trailer in the building). Paint Booths are protected by Extra Hazard II and pose the most demand for the occupancy. On Mon, Mar 28, 2011 at 6:07 PM, jd gamble <[email protected]> wrote: > Have a new 46K sq. ft. warehouse being utilized for commercial vacuum (car > wash) manufacturing. Building should fall under ORD I. Local authority has > challenged the engineered drawing (state requirement), calling for the > building to be ORD II. This creates some serious issues as you can > imagine. Any thoughts on a 'defense' of the ORD I position? > > > _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
