Thermoplastic Spray Nozzle Sealing via Pressurized Liquid Force
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Solution Overview
Problem
Existing spray nozzle units face challenges in maintaining a liquid-tight seal and preventing microbial ingress under high operating pressures and varying temperatures, especially when using medical-grade thermoplastic materials, which are prone to leakage and bacterial integrity issues without the use of glues or solvents.
Innovation Solution
A spray device design featuring a thermoplastic holder with a polymer rim that sealingly engages the nozzle plate, creating a liquid-tight seal by using the pressurized liquid to press the nozzle plate against the rim, and optionally including a second rim between the nozzle and prefilter plate, along with a conical adapter to counterbalance pressure forces, ensuring a hermetic seal and bacterial integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If medical grade thermoplastic materials are used for the holder, then the device is biocompatible and safe for pharmaceutical use, but the holder is prone to internal leakage and loss of bacterial integrity under high operating pressures and varying temperatures
Solution Approach 1:
A flexible membrane made of PTFE (polytetrafluoroethylene) is introduced as a barrier layer between the thermoplastic holder and the nozzle plate. This thin film acts as an impenetrable barrier to microbes while allowing the thermoplastic holder to maintain its biocompatible properties. The membrane prevents microbial ingress through the holder material under high operating pressures and varying temperatures.
2Reliability
If glue, solvents or sealing agents are used to mount the nozzle plate, then the sealing is improved, but the device is no longer suitable for pharmaceutical applications due to contamination risks
Solution Approach 1:
The harmful sealing agents (glue, solvents, sealing agents) are completely removed from the assembly process. Instead, a mechanical sealing solution is implemented using a tapered seat geometry that creates a tight fit between the nozzle plate and holder through precision machining, eliminating the need for any chemical sealing materials that could contaminate pharmaceutical products.
Solution Approach 2:
A flexible PTFE membrane is introduced as a sealing barrier that does not require glue or solvents. This thin film provides the necessary sealing function while being compatible with pharmaceutical applications, as it can be sterilized and does not leave residual contaminants.
3Stress or pressure
If the nozzle plate is securely mounted to withstand high operating pressures, then the device can function at 1-50 Bar pressures, but the nozzle plate may still become loose or ejected under peak pressures
Solution Approach 1:
The sealing interface is designed to be dynamic rather than static. The tapered seat geometry allows the nozzle plate to maintain constant contact pressure against the seat surface as operating conditions change. This self-adjusting mechanism ensures the nozzle plate remains securely retained even under peak pressures, preventing ejection while accommodating pressure variations.
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 design achieves a reliable liquid-tight seal and bacterial integrity across a broad temperature and pressure range without the need for glues or solvents, effectively preventing microbial ingress and ensuring safe operation of the spray device.
Implementation Method 1
a force of the pressurized liquid in operation presses the nozzle plate against the rim so as so seal the nozzle plate thus prevent liquid from leaking around the nozzle plate
Data Source
AI summary
A method for manufacturing an spray device includes assembling at least one spray nozzle plate into a thermoplastic holder, while controlling the temperature of the spray nozzle plate and/or the holder and as a result at least locally plastically deforming the holder permanently. After the thermoplastic deformation of a seat of the holder, a diameter of the seat of the holder upstream of the spray nozzle plate exceeds a diameter of the seat of the holder downstream of the nozzle plate. The thermoplastic holder may have a tapered seat, where the smallest cross section of the tapered seat is smaller than the spray nozzle plate, where a widest side of the tapered seat is pointing towards a supply side of the liquid.