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        # The Perfect Bend: Optimizing PHR Ratios for Flexible Hoses

        

**Topic:** Production

        

Your garden hoses are either too stiff to coil or so soft they kink and block the water flow. Finding the 'Goldilocks' zone of flexibility is a science.

        
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## Problem

The flexibility of PVC is determined by the Parts Per Hundred Resin (PHR) of plasticizer. Too little, and the hose is brittle; too much, and it loses structural integrity and the plasticizer starts to 'bleed' out (migration).

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## Likely cause

This issue often stems from inconsistent compounding temperatures, inferior raw material purity, or unbalanced stabilizer ratios within the formulation matrix.

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## Corrective direction

For a standard flexible hose, a PHR of 40-60 of NBT DOP or DOTP is typical. However, to prevent kinking, a small amount of NBT CPW (10-15 PHR) can be added. This acts as a secondary plasticizer that improves the 'hand-feel' and reduces the overall cost of the formulation.

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          ## Frequently Asked Questions

          
### What is the best resin for flexible hoses?

A high K-value resin like NBT SG-7 (K-70) is preferred as it provides better mechanical strength at high plasticizer levels.

### How do I stop the hose from smelling like chemicals?

Using high-purity NBT plasticizers with low volatile content significantly reduces the 'new hose' odor.

        
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By NBT Technical Desk · Updated 2026-06-07

        

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