This year the OH Fire code is undergoing revisions to bring it up to the 2015 IFC requirements.  In this process, there is a comment period in which anyone with interest can make comments on the proposed revisions or ask questions.  One such question was asked about the revisions to

5704.2.7.3.2. Vent Line Flame Arresters and Pressure-Vacuum Vents

Is the intention to require flame arrestors or pressure-vacuum vents ONLY for Class 1B and Class 1C liquids? (emphasis added by me)

From the commenter:

Starting the paragraph with “Where installed” seems to suggest that these are not required or at least there are circumstances where they may not be required.  Is this addressed by the reference to section 21.4.3 of NFPA 30 for pressure-vacuum vents?

Section 21.4.3 of NFPA 30 requires either flame arrestors or pressure vacuum vents for Class 1B and Class1C liquids (21.4.3.9) and pressure-vacuum vents for Class 1A liquids (21.4.3.8) with some exceptions (21.4.3.10 and 21.4.3.11).

The installation and maintenance requirements further confuse the requirements since in several cases they refer to NFPA 30 or API 2000. The requirement was more clearly stated in former section 3404.2.7.3.6 which specifically required vent line flame arresters or pressure-vacuum vents for Class 1B and Class 1C vents.  

There seems to be two issues to be addressed here:

(1) the requirement for the devices and

(2) the requirements for installation and maintenance.

An approach would be to revise the opening sentence as [above]:

 

Committee Reason:

The language contained in 5704.2.7.3.2 is national language. Generally, all tanks containing flammable and combustible liquids are required to have normal vents pursuant to NFPA 30.  The provision at issue here speaks beyond that requirement to address specifically tanks containing Class 1B and Class 1C liquids, which are required to not just generally have normal vents, but to have either flame arresters or pressure-vacuum vents that remain closed unless venting under pressure or vacuum conditions.

This requirement does not apply to tanks containing Class 1A liquids. Tanks containing Class 1A liquids must have normal vents, but are not required to have vent line flame arresters or pressure-vacuum vents that remain closed unless venting under pressure or vacuum conditions. (Emphasis added.) Pursuant to code commentary produced by the ICC, the ICC did intend that this requirement would not apply to tanks containing Class 1A liquids because the use of such devices on tanks containing Class 1A liquids is not effective.

Although the application of the referenced standards is broken down, the applicable standard for each type of equipment is provided for in the rule (for example, the installation of vent line flame arresters is governed by API 2000 and their maintenance is governed by a specified provision of NFPA 30 or API 2000).

The use of the term “when required” denotes the exception contained in the provision, rather than an overall indication that the equipment is sometimes necessary and sometimes not necessary for tanks containing Class 1B and Class 1C liquids. Flame arresters or pressure-vacuum vents that remain closed unless venting under pressure or vacuum conditions are required for tanks containing Class 1B and Class 1C liquids except in cases where the fire code official has determined that the use of such devices can result in damage to the tanks. Therefore, because the national language together with its relevant commentary on this matter, provides clarification on this provision and its applicability, no further changes will be made in the 2017 OFC.

 

Source: http://www.com.ohio.gov/documents/fire_2017OFCFinalROC.pdf

 
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