10.6 Sizing and Flow Velocities.

10.6.1 PEX tubing shall be sized in accordance with IAPMO/ANSI UPC 1. Note: Potable water piping sizing is addressed in Section 610.0 and Appendix A of IAPMO/ANSI UPC 1-2012. 10.6.2 The tubing manufacturer’s pressure-loss data should be referenced when using Appendix A of IAPMO/ANSI UPC 1. In absence of such data, Figures 3 and 4 shall be used. 10.6.3 Flow velocities through the water distribution system, used for calculating flush tank and flush valve fixture units depending on the tubing sizes (see Table 1), shall not exceed (a) 3.0 m/s (10 ft/s) for cold-water distribution

systems; and (b) 2.4 m/s (8 ft/s) for hot-water distribution

systems. Note: The flow velocities in Items (a) and (b) account for the increased velocities through the fittings. 10.6.4 Hot-water recirculation systems shall (a) be balanced to maintain adequate system

temperatures; and

(a) expressly allowed in the written instructions

of the manufacturers of all plastic pipe and

(a) expressly allowed in the written instructions

of the manufacturers of all plastic pipe and fittings installed at the time the PEX piping system is being tested; and (b) compressed air or other gas testing is not

prohibited by the authority having jurisdic

compressed air or other gas testing is not

prohibited by the authority having jurisdiction.

(a) 3.0 m/s (10 ft/s) for cold-water distribution

systems; and (b) 2.4 m/s (8 ft/s) for hot-water distribution

systems.

Note: LB = C × √(D × ΔL) where LB = length of flexible arm C = material constant (12 for PEX) D = nominal outside diameter of tubing ΔL = thermal expansion length

FIGURE 1 (See Sections 6.4.1 and 7.3) EXPANSION ARMS

(a) be balanced to maintain adequate system

temperatures; and (b) have flow velocities that do not exceed 0.6

m/s (2 ft/s) (see Table 2); and

(b) have flow velocities that do not exceed 0.6

m/s (2 ft/s) (see Table 2); and (c) use only PEX tubing designated for hot,

chlorinated water recirculation systems and

(c) use only PEX tubing designated for hot,

chlorinated water recirculation systems and rated for the maximum percentage of time during which the system is intended to be operated at elevated temperatures, in accordance with ASTM F876.