PVC piping in a plenum return application?

[HVACQuestions]

I have some lab spaces using plenum style return systems, does this mean I need to fire wrap any existing PVC piping above the ceiling in those areas? I don't see anything in IMC that stipulates this.

 

[mtlogcabin]

2018 IMC
602.2.1.7 Plastic plumbing piping and tubing.
Plastic piping and tubing used in plumbing systems shall be listed and labeled as having a flame spread index not greater than 25 and a smoke-developed index not greater than 50 when tested in accordance with ASTM E84 or UL 723.

Exception: Plastic water distribution piping and tubing listed and labeled in accordance with UL 2846 as having a peak optical density not greater than 0.50, an average optical density not greater than 0.15, and a flame spread distance not greater than 5 feet (1524 mm), and installed in accordance with its listing.

 

[jar546]

2018 IMC
602.2.1.7 Plastic plumbing piping and tubing.
Plastic piping and tubing used in plumbing systems shall be listed and labeled as having a flame spread index not greater than 25 and a smoke-developed index not greater than 50 when tested in accordance with ASTM E84 or UL 723.

Exception: Plastic water distribution piping and tubing listed and labeled in accordance with UL 2846 as having a peak optical density not greater than 0.50, an average optical density not greater than 0.15, and a flame spread distance not greater than 5 feet (1524 mm), and installed in accordance with its listing.

It is more than just plastic piping that comes into play when you have a plenum space. I would review all of 602.2.1

 

[mtlogcabin]

Agree but the question was related to plumbing piping.

 

[mtlogcabin]

Rabbit trail and my 2 cents
Other thoughts and opinions?

If an approved area smoke detector system is installed in a return air plenum and it shuts down the HVAC system do we really need to be concerned about what materials are within the plenum?
Restriction of materials within a plenum have been in the codes since before the 1970s that I am aware of and the advancements made within the smoke detection and notification industry in the last 40 years have been phenomenal.
Would there be less cost associated with a detection and notification system installed versus a passive system of restricting materials within a plenum that has been in the code for almost a century?
Would an active smoke detection and notification system provide a higher level of safety for the occupants versus todays code requiremnts?

 

[Paul Sweet]

If the piping is existing then the Existing Building Code would apply. We have always been required to use plenum-rated ($$$) piping for new labs.

 

[mtlogcabin]

Not automatically
2018 IMC
[A] 102.2 Existing installations.
Except as otherwise provided for in this chapter, a provision in this code shall not require the removal, alteration or abandonment of, nor prevent the continued utilization and maintenance of, a mechanical system lawfully in existence at the time of the adoption of this code.

Plenum requirements have been around for a long time 40 + years that I know of so if the plenum was not code compliant at the time of construction it is not code compliant today

 

[mtlogcabin]

does this mean I need to fire wrap any existing PVC piping above the ceiling in those areas?

Be careful what you use to wrap the pipes with

https://www3.iccsafe.org/cs/committeeArea/pdf_file/ME_15_64_17.pdf

INTERNATIONAL MECHANICAL CODE Page 1 of 1 CHAPTER 6 DUCT SYSTEMS SECTION 602.2.1 2015 Edition IMC Interpretation No. 64-17 Issued: 05-01-2018 ME_15_64_17
602.2.1 Materials within plenums. Except as required by Sections 602.2.1.1 through 602.2.1.7, materials within plenums shall be noncombustible or shall be listed and labeled as having a flame spread index of not more than 25 and a smoke-developed index of not more than 50 when tested in accordance with ASTM E 84 or UL 723. Exceptions:
1. Rigid and flexible ducts and connectors shall conform to Section 603.
2. Duct coverings, linings, tape and connectors shall conform to Sections 603 and 604.
3. This section shall not apply to materials exposed within plenums in one- and two-family dwellings.
4. This section shall not apply to smoke detectors.
5. Combustible materials fully enclosed within one of the following:
5.1. Continuous noncombustible raceways or enclosures.
5.2. Approved gypsum board assemblies.
5.3. Materials listed and labeled for installation within a plenum. 6. Materials in Group H, Division 5 fabrication areas and the areas above and below the fabrication area that share a common air recirculation path with the fabrication area. ● ● ● ● ● ● ● ● ● ●
Q: Does Exception 5 permit the use of any material as an approved enclosure of combustible items provided that the material is listed and labeled as having a flame spread index of not more than 25 and a smoke-developed index of not more than 50 when tested in accordance with ASTM E 84 or UL 723?
A: No. The material within the plenum is permitted to be any material labeled as having a flame spread index of not more than 25 and a smoke-developed index of not more than 50 when tested in accordance with ASTM E 84 or UL 723.
Exception 5 provides three methods of protecting the combustible material found within the plenum where such material does not meet the flame spread / smoke-developed index.
Exception 5, part 5.3 requires the material that encloses the combustible material to be listed and labeled for installation within a plenum. Simply because the material meets the flame spread and smoke-developed index of this section does not mean that it can be used to enclose combustible material. The material that encloses the combustible material must be specifically listed and labeled for installation within a plenum. ___________________________________________________________________________