Low Molecular Weight PEG Replaces DGME in Firefighting Foam
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Solution Overview
Problem
Conventional firefighting foam concentrates containing diethylene glycol monobutyl ether (DGME) are toxic to humans and aquatic wildlife, posing environmental concerns due to runoff issues during firefighting operations.
Innovation Solution
The use of low molecular weight poly(ethyleneglycol) (PEG) with a weight average molecular weight of about 200 replaces DGME in firefighting foam concentrates, providing comparable performance with significantly lower toxicity and allowing for the creation of DGME-free concentrates that include fluorinated and non-fluorinated surfactants, polysaccharide gums, biocides, corrosion inhibitors, and electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diethylene glycol monobutyl ether (DGME) is used as a foam stabilizing solvent and wetting agent, then concentrate stability and firefighting solution stability are improved, but toxicity to humans and aquatic wildlife increases
Solution Approach 1:
The patent substitutes DGME with poly(ethylene glycol) having a weight average molecular weight of about 200, which has similar physical properties (viscosity, solubility) but significantly lower toxicity. This parameter change in molecular structure and composition maintains the foam stabilizing and wetting functions while reducing harmful effects on humans and aquatic wildlife.
2Stability of the object's composition
If DGME is used as a solvent in firefighting foam concentrates, then foam stability is improved, but environmental impact due to runoff increases
Solution Approach 1:
The invention replaces DGME with low molecular weight poly(ethylene glycol) (Mw ≈ 200) that provides equivalent foam stability through similar surfactant interaction mechanisms, but with reduced environmental persistence and toxicity, thereby minimizing harmful runoff effects on aquatic ecosystems.
3Object-affected harmful factors
If poly(ethyleneglycol) with weight average molecular weight of about 200 is used to replace DGME, then toxicity is reduced, but concentrate stability must be maintained
Solution Approach 1:
The patent identifies that poly(ethylene glycol) with a weight average molecular weight of about 200 provides the optimal balance between reduced toxicity and maintained concentrate stability. This specific molecular weight parameter ensures adequate solubility, viscosity, and interaction with fluorinated surfactants to maintain foam concentrate stability while achieving significantly lower toxicity compared to DGME.
Data Source
AI summary
It has been discovered that low molecular weight poly(ethyleneglycol) (PEG) can be used in place of diethylene glycol monobutyl ether (DGME) in fire foam concentrates without compromising the desirable properties provided by DGME. Surprisingly it has been found that lower molecular weight PEG with a weight average molecular weight Mw of 400 or less provides comparable performance to DGME with considerably lower toxicity. Use of this PEG permits preparation of fire foam concentrates that exclude DGME completely and that are less toxic than conventional DGME-containing concentrates.