Eldon James produces premium nylon fittings in a variety of styles and sizes. Their 1/4 NPT threads have the Whitworth thread form, designed to provide a pressure-tight fit through the mating of the threads. Accomplished by cutting the threads on a taper, this assures that the male thread can only screw into the companion female thread a certain distance before it jams. The standard specifies this distance as a length based on hand-tight engagement; a convenient rule-of-thumb for plastic threads is finger-tight plus 1/2 to 1 turn with a wrench. Do not over-tighten plastic threads stress on the fitting can result in its failure.Our Single Barb Fittings Features and Clamp Dynamics. The threads are molded in precision-ground cavities resulting in perfectly matched threads at the parting line. This produces the cleanest, most accurate molded thread possible.
Why our fittings are better.
Our single-barbed fittings are designed so the mold parting line stops at the base of the barb. The ridge and the barb’s conical surface are free of the molded-in leak path present in multiple barb fittings. The conical surface on an Eldon James fitting is glass-like and smooth allowing excellent sealing.
The straight barb shaft provides space for the hose to relax behind the barb causing the clamp to work like a drawstring. This forces the hose diameter to become smaller than the flare of the fitting’s barb. If the tubing swells from internal pressure (near burst), the clamp will be pulled up tight to the back of the barb and a tight seal will be maintained.
| Single Barb Fitting ( Eldon James Fitting) |
OtherBarb Fitting | |||
| Clamp placement on a single barb fitting. Clamp positioning in the recess behind the barb allows for tubing compression anterior to the barb and results in a secure seal with without excessive clamp pressure |
Clamp placement on a Multiple barb fitting. Clamp can only be placed over barb. In general, much more clamp pressure is required to secure a seal than that necessary with a single barb fitting |
Why multiple barb fittings failMismatches often occur with poor quality or worn tooling, causing misaligned threads and barbs that result in leakage. With multiple barb fitting designs, it is virtually impossible to avoid creating parting lines on the barb surface. These parting lines create leak paths which become more pronounced as the mold tooling wears.
| Multiple Barb Fitting – Clamp Dynamics | ||
| 1. Clamping on a barb’s outer radius, in an m attempt to force the tube down behind the barbs can cause damage. The sharp edges of the barbs become rounded resulting in less bite into the tubing.
2. Clamping pressure causes the tube to flare out behind the clamp and barbs located behind the clamp will have little or no effect. |
Multiple barbs are typically in close succession. This prevents the tubing from relaxing
to its original size, which is essential to the barb’s performance. If the tubing does not
relax behind the barb, the barb is rendered useless, as shown above. (Note the bridging effect.)
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