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 Flexible Tubing
Makes For
Easy Installations
By Marcia Sampson
Summary: Here water treatment dealers are invited to look at flexible tubing in a whole new light. Where a discussion comparing the differences between single-barb and multiple-barb fittings takes center stage

dvances in polymer chemistry over the past two decades have resulted in improved formula-
tions that have increased flexible tubing's flexibility and elasticity and have made it an ideal safe choice for potable water treatment applications.
  The excellent flexibility and elasticity exhibited by modern polyethylene, poly-urethane and PVC tubing formulations provide a number of benefits for system designers and installers, including:
  • Tight radius bends that can be     negotiated without kinking or flow     restriction,
  • Simplified design layout that     allows bends and turns to be made
    with the tubing instead of the     connectors (in rigid tubing designs,     additional connectors are required at     each turn point which increases the     complexity of the system),
  • NSF Standards 61 and  51 certified     flexible tubing is widely available
    in sizes and configurations to meet     almost any requirement,
  • A superior seal results when flexible     tubing is coupled with single-barb     fittings and ...
  • Single-barb fittings take full advantage     of flexible tubing"s elastic memory     properties virtually eliminating the need
 

   for clamps in many situations (see    below).
  
A single barb fitting's engagement with an elastomer tubing comes closer to a radial O-ring seal than does a multiple barb fitting's, since a single barb allows the tub-ing to relax more snugly behind the barb .

Expanded options
  With the introduction of Standard 61 certified tubing and NSF certified single-barbed connectors (see fig.1), the pos-sibilities are greatly expanded for creating compact systems that fit comfortably within confined areas. With an installation that uses rigid tubing and push-on con-nectors, a primary concern, in tight spaces, is the potential for leaks resulting from misalignment and lateral stress at the connector. This isn't a a concern with flexible tubing / single-barb connector designs. In addition there's a tendency for rigid tubing to transmit water hammer, and expansion and vibration forces to the point of connection. In a large installation, the

Figure 1. Single barb fitting


 

rigid tubing will absorb some of this stress. However, In an installation with shorter runs, almost all of the vibration is transferred. In a flexible tubing installation, stress and vibration are dampened and absorbed regardless of the length of tub-ing used. This often results in much quieter operation and increased reliability for the entire system.

Single-barb fittings
  Single-barb connectors are an essential component for building systems with flexible tubing. They offer both safety and mechanical advantages when compared with multiple-barbed fittings (see fig.2). With a single-barb fitting design, it's possible to manufacture a barb without a mold parting line. This is essentially im-practical with multiple barb designs. Parting lines can be a source of leaks in
a connection and provide a pathway for bacterial and fungal migration.

                          
                                  Page 2 >>

Figure 1. Multiple barb fitting

 

Water Conditioning & PurificationJuly 2003
                                           << Back                                                                                       updated 10/2004