Reducing Your Oven's Hazards, Part 3
NFPA 86 states: The heat processing of materials involves serious fire and explosion hazards that can endanger the equipment, building or personnel.
This is the third in a four-part series intended to summarize the key points of the requirements for safety shutoff valves in combustion systems. It is not a comprehensive summary of all NFPA requirements for ovens and furnaces.
In Part 1 (September 2004, p. 25), some of the requirements summarized for fuel-gas safety shutoff valves referred only to independently operated burners, as follows:
The above synopsis simplifies the explanation of the safety-shutoff-valve requirements by only considering their application to an independently operated burner. The summary does not indicate that these requirements also apply to a burner system.
NFPA 86, 3.3.6 Burner System, addresses one or more burners operated as a unit by a common safety-shutoff valve(s). To be inclusive of both independently operated burners and simultaneously operated burners arranged in a burner system, the above synopsis can be modified as follows:
The above three items highlights the difficulty in providing a summary that covers all aspects of the NFPA 86. One word can change the requirement, so care must be taken by the user to gain an understanding of the entire standard as well as any other standard or code referred to by the governing standard.
Thus far we have only discussed fuel-gas applications. The requirements for safety-shutoff valves for fuel-oil systems are similar to those for fuel gas but not exactly the same. Here is the exact language of the standard regarding fuel-oil safety shutoff-valve requirements.
7.7.3 Oil Safety-Shutoff Valves
(1) Where the pressure is greater than 125 psi (862 kPa).
(2) Wherever the fuel-oil pump operates without the main oil-burner firing, regardless of the pressure.
(3) For combination gas and oil burners, where the fuel-oil pump operates during the fuel-gas burner operation.
Please note that the requirements of 184.108.40.206 for local visual indication of valve position for inputs in excess of 150,000 BTU/hr also applies to fuel-oil safety shutoff valves and that the requirements of 220.127.116.11 are not predicated on any particular BTU/hr capacity as for fuel-gas applications.
There are other requiremnts for safety shutoff valves that will not be covered in Safety Zone, so please refer to Chapter 7.7 Safety Shutoff Valves (Fuel Gas or Oil) in the 2003 edition of NFPA 86. PH