Multilayer Rotomolded Grease Trap Structural Integrity
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Solution Overview
Problem
Conventional grease traps, especially rotomolded passive ones, face issues with expense and delay due to the need for a concrete pour during installation and are prone to bulging when filled with grey water or FOG, which can weaken the structure.
Innovation Solution
A rotomolded grease trap with a multilayer outer wall comprising an outer layer of un-foamed plastic, an intermediate layer of foamed plastic, and an inner layer of un-foamed plastic, which provides enhanced strength and stability, eliminating the need for a concrete pour and preventing bulging, along with a divider to separate FOG from water and a sloping bottom for efficient solid collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-ply rotomolded grease trap is used, then the structure is simple and cost-effective, but it is prone to bulging and weakening when filled with grey water and FOG
Solution Approach 1:
The grease trap tank employs a multilayer composite wall structure consisting of an outer layer of un-foamed plastic, an intermediate layer of foamed plastic, and an inner layer of un-foamed plastic. This composite construction combines the structural strength of un-foamed plastic with the buoyancy control and cushioning properties of foamed plastic, preventing bulging and maintaining structural integrity when the tank is filled with grey water and FOG.
Solution Approach 2:
The intermediate layer of foamed plastic acts as a counterweight mechanism, providing buoyancy control that prevents the tank from sinking or deforming under the weight of the contents. The foam layer's lower density creates an upward force that counteracts the downward pressure from the grey water and FOG, maintaining the tank's structural stability.
2Reliability
If a concrete pour is added for underground installation, then the structural support is improved, but the installation expense and time are increased
Solution Approach 1:
The multilayer tank structure is self-supporting and self-reinforcing, eliminating the need for external concrete reinforcement. The composite wall structure inherently provides the necessary structural strength and stability for underground installation, allowing the tank to be installed directly without requiring additional concrete pouring steps.
Solution Approach 2:
The tank's structural parameters have been optimized through the multilayer construction, changing the material composition and wall structure to provide adequate support without external reinforcement. This parameter change in the tank's inherent strength allows it to withstand underground installation conditions without requiring concrete encasement.
3Quantity of substance
If the tank wall is made thinner to reduce material, then the manufacturing cost is reduced, but the resistance to bulging and deformation is weakened
Solution Approach 1:
The multilayer composite structure achieves high deflection resistance with reduced overall material quantity by combining different plastic layers with complementary properties. The un-foamed layers provide structural strength while the foamed layer provides buoyancy control, creating an efficient material distribution that maximizes strength-to-weight ratio.
Solution Approach 2:
Different layers of the wall structure have different local qualities optimized for specific functions: the un-foamed outer and inner layers provide structural strength and resistance to deformation, while the intermediate foamed layer provides buoyancy control and cushioning. This localized optimization of material properties achieves high deflection resistance without requiring uniform thick walls throughout.
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
The multilayer construction enhances the deflection strength of the tank, allowing for reduced installation costs and increased durability, preventing inward and outward deflections, and allowing for efficient separation and collection of FOG and solids, reducing the frequency of emptying and maintenance.
Implementation Method 1
The tank preferably has at least one divider dividing the tank into an upper chamber and a lower chamber... The intermediate layer of foamed plastic provides structural support and buoyancy control
Implementation Method 2
The outer wall has a bottom downwardly sloping from a tank perimeter to a central location, the inlet invert opens above the bottom so that solids in the waste water gravitationally separate towards the bottom
Implementation Method 3
The outer layer may have a density of about 60 pounds (27.21 kg) per cubic foot and the intermediate layer may have a density of about 15 pounds (6.8 kg) per cubic foot
Data Source
AI summary
A grease trap or solids collector for separating waste from waste water has a tank having a multilayer outer wall made of an outer layer of un-foamed plastic, an intermediate layer of foamed plastic, and an inner layer of unfoamed plastic; an inlet invert in the tank for receiving incoming waste water; and an outlet invert for removing water from the tank. An extension collar made up of segments can be included.