Variable Foam Orifice for Temperature-Stable Venturi Proportioning
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Solution Overview
Problem
Fire suppression systems using venturi-principle foam proportioning mechanisms struggle to maintain accurate foam concentrate proportioning across a wide range of temperatures due to changing viscosities of firefighting foam concentrates, limiting their operational range and effectiveness.
Innovation Solution
A fire suppression system incorporating a venturi-principle foam proportioner with a thermo-responsive variable orifice that adjusts based on temperature, using a thermostatic actuator to modify the orifice area and maintain a consistent water/foam ratio by accounting for changes in foam concentrate viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed orifice proportioner is used, then the device complexity is low, but the proportioning accuracy deteriorates across wide temperature ranges due to viscosity changes
Solution Approach 1:
The patent applies a variable orifice design where the orifice size dynamically adjusts based on foam concentrate viscosity. The orifice includes a movable plate that can change its position to modify the opening size, transforming a static component into a dynamic one that adapts to changing operating conditions (temperature and viscosity variations) to maintain accurate proportioning.
Solution Approach 2:
The patent changes the physical parameter of the orifice size based on viscosity measurements. When viscosity increases (due to temperature changes), the orifice size is automatically adjusted to compensate, ensuring that the flow rate of foam concentrate remains proportional to the water flow rate despite varying concentrate properties.
2Reliability
If the orifice size is increased to accommodate higher viscosity foam, then the proportioning accuracy at low viscosity deteriorates
Solution Approach 1:
The variable orifice mechanism allows the system to dynamically adjust the opening size based on real-time viscosity conditions. This dynamic adjustment capability enables the system to maintain optimal proportioning accuracy across the entire temperature range, rather than being optimized for a single fixed viscosity condition.
Solution Approach 2:
The system changes the orifice size parameter in response to viscosity changes. When foam concentrate viscosity increases, the orifice size is increased to maintain flow; when viscosity decreases, the orifice size is reduced. This parameter adaptation ensures consistent proportioning accuracy across varying operational conditions.
3Adaptability or versatility
If a variable orifice mechanism is added, then the proportioning accuracy across temperatures improves, but the device complexity increases
Solution Approach 1:
The proportioning system incorporates self-regulating features where the variable orifice mechanism automatically adjusts based on viscosity changes in the foam concentrate. The system monitors its own operating conditions and makes necessary adjustments without external intervention, reducing the need for manual calibration and complex control systems.
Solution Approach 2:
The patent implements a feedback mechanism where viscosity changes are detected and used to control the orifice size. The system continuously monitors the foam concentrate properties and adjusts the variable orifice accordingly, creating a closed-loop control system that maintains accurate proportioning across varying temperatures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective proportioning of foam concentrates across a broader temperature and viscosity range, ensuring consistent fire suppression performance even with foams that exhibit significant viscosity changes, thereby expanding the operational range of the system.
Implementation Method 1
The thermally sensitive material can be configured to expand when the temperature associated with the foam concentrate reaches a minimum working temperature, such that the first section of the piston is acted on by the expansion of the thermally sensitive material
Implementation Method 2
venturi-principle foam proportioning mechanisms
Data Source
AI summary
A fire suppression system includes a water supply, a foam concentrate supply, and a venturi-principle foam proportioner fluidly coupled to each of the water supply and the foam concentrate supply. The venturi-principle foam proportioner controls a ratio of water and foam concentrate within a low pressure chamber to form a water and foam solution flowing out of the venturi-principle foam proportioner. The system also includes a variable foam concentrate orifice fluidly coupling the foam concentrate line to the low pressure chamber. The variable foam concentrate orifice includes an actuator configured to adjust an orifice area of the variable foam concentrate orifice based on a temperature of the foam concentrate.