Nozzle Diameter Research Articles

The microstructural evolution of material extrusion based additive manufacturing of polyetheretherketone under different printing conditions and application in a spinal implant

AbstractWith the advances in additive manufacturing, polyetheretherketone (PEEK), a biocompatible polymer, can be used in biomedical applications such as spinal implants. This paper aims to investigate the evolution of the microstructure of PEEK parts manufactured by material extrusion (MEX)‐based additive manufacturing with different printing parameters. The effect of layer thickness (LT) and nozzle diameter on mechanical properties was investigated using tensile, Charpy impact, and short beam strength (SBS) tests. Two different LTs, 0.1 and 0.2 mm, and two different nozzle diameters, 0.6 and 0.8 mm, were used as printing parameters. By increasing the LT, tensile strength dropped by around 24%, and impact strength by almost 55%. Moreover, altering the LT resulted in a 15% decrease in interlaminar shear strength (ILSS) from the SBS test. In addition, increasing the nozzle diameter also led to a significant reduction in all of the results as tensile strength, Charpy impact strength, and ILSS. The results were also consolidated by scanning electron microscopy. The main findings were that increasing LT leads to an increase in microstructural defects that act as stress concentrators. Following the tests, response surface methodology (RSM) was used to determine optimal printing parameters. In the end, using the optimum printing parameters from the RSM study, a structural analysis of a MEX‐printed spinal implant was conducted through finite element method, considering the loading cases mimicking daily human body motions.Highlights As layer thickness increased, tensile and impact strength dropped. Tensile and impact strength dropped truly with increasing nozzle diameter. SEM revealed that increasing layer thickness causes more microstructural flaws. FEM analysis showed that PEEK‐based implant provides structural integrity.

A novel approach for solidification enhancement of phase change materials through direct contact with a boiling fluid: An experimental investigation and visualization

Due to their remarkable properties, such as high latent heat and stable temperatures during phase transitions, phase change materials (PCMs) are widely used in thermal energy storage (TES) and thermal management systems (TMSs). However, their low thermal conductivity has limited their broader application across various industries. This study experimentally explores, for the first time, the effects of injecting boiling fluid (BF) into the PCM container as a new method to enhance heat transfer during the solidification process of PCM. To this end, Paraffin wax and acetone with saturation temperature lower than paraffin’s freezing point are selected as PCM and BF, and the influence of four various parameters, namely the initial PCM temperature (75, 85, and 95 °C), the height of the PCM inside the container (15 cm, 25 cm, and 35 cm), the flow rate of the BF (0.32, 0.46, and 0.57 L/min), and the nozzle diameter (2 mm, 3 mm, and 4 mm), on the solidification behavior of PCM, temperature distribution inside the container, and heat transfer enhancement (released energy and Nusselt number) is thoroughly scrutinized. In order to visualize and further evaluate the two simultaneous phase transitions (vaporization of the BF and solidification of the PCM), a Hele-Shaw cell with a height, width, and thickness of 50, 20, and 1 cm is considered as the PCM storage system. The findings indicate that when the BF is injected into the paraffin storage, the high heat transfer coefficient of boiling superbly improves the thermal behavior of PCM, and the solidification process occurs in a much shorter time. Also, boiling of the acetone inside the container and its direct contact with paraffin leads to a significant mixing inside the container and the creation of vortices and turbulent flow in the system, which further improves the freezing phenomenon. Furthermore, it was observed that regardless of other parameters, the flow rate of BF is the most crucial parameter, and after that, the height of the paraffin and the initial temperature have the greatest impact. By employing the highest flow rate, the proposed technique is capable of freezing 0.7, 0.5, and 0.3 L of paraffin in 48, 33, and 18 s, respectively, indicating multiple times of improvement in the full solidification time compared to previous studies.

Three-Dimensional Printing of PVA Capsular Devices for Applications in Compounding Pharmacy: Effect of Design Parameters on Pharmaceutical Performance.

The creation of products with personalized or innovative features in the pharmaceutical sector by using innovative technologies such as three-dimensional (3D) printing is particularly noteworthy, especially in the realm of compounding pharmacies. In this work, 3D printed capsule devices (CDs) with different wall thicknesses (0.2, 0.3, 0.4, 0.6, and 0.9 mm) and sizes were designed and successfully fabricated varying printing parameters such as extrusion temperature, printing speed, material flow percent, and nozzle diameter. The physicochemical, pharmaceutical, and biopharmaceutical performance of these CDs was evaluated with the aim of achieving an immediate drug release profile comparable to hard gelatin capsules (HGC) for use in magistral compounding. It was observed that the disintegration time of the CDs increased with wall thickness, which correlated with a slower drug release rate. CDs with configurations presenting 0.4 mm wall thickness and sizes comparable to HGC n° 0, 1, and 2 demonstrated satisfactory weight uniformity, short disintegration times, and immediate drug release, indicating their potential as effective devices in future compounding pharmacy applications. In addition, a modified Weibull-type model was proposed that incorporates wall thickness as a new variable in predicting dissolution profiles. This model improves the process of selecting a specific wall thickness to achieve the desired dissolution rate within a specified time frame.

Experimental study on the flame trajectory evolution of horizontal jet fires under reduced pressures

Jet fire including process pipeline/tank leakage, oil exploitation industry of tail gas treatment flare or other industrial combustors as a common phenomenon can be found at high altitude areas. This work characterizes the flame trajectory evolution of horizontal jet fires under reduced pressures, which is rarely studied. The experimental results show that the horizontal flame projection distance increases monotonously, but the vertical flame length first increases and afterward decreases with the increase of heat release rate and the decrease of ambient pressure. Meanwhile, flame trajectory length increases significantly and then slowly with increasing heat release rate, but first increases to a maximum value and afterward declines with decreasing ambient pressure. Meanwhile, the turning point of vertical flame length appears earlier than that of flame trajectory length with increasing heat release rate (or jet velocity at source) and decreasing ambient pressure. Then, a mathematical model based on the flame arc hypothesis and a dimensionless model were proposed to describe the flame trajectory length, the momentum-buoyancy length scale Lm=(M0/g′)1/3 was used to normalize the flame trajectory length. The measured flame trajectory length in terms of the nozzle diameter, heat release rate, and ambient pressure was satisfactorily correlated by the proposed models.

Dependence of Pressure Characteristics of Pressurized Pulse Water Jet Chamber on Nozzle Diameter

The nozzle is the key element of the water jet generator for energy conversion. In order to explore the influence of the nozzle diameter on the pressure characteristics of the supercharged pulsed water jet plenum chamber, a supercharged pulsed water jet pressure acquisition system was established, and the equations of motion and theoretical pressurization ratio equations of the supercharged pulsed water jet generator were established. The pressurization chamber pressure acquisition experiments under different nozzle diameters were carried out. The research results show that the pressurized pulsed water jet generator has a critical nozzle diameter of 0.6 mm. When the nozzle diameter is less than the critical diameter, the pressure in the boost chamber is equal to the product of the driving pressure and the boost ratio. As the nozzle changes, there is no significant change in the peak pressure and frequency of the boost chamber. When the nozzle diameter is greater than the critical diameter, there is a non-linear relationship between the boost chamber pressure and the driving pressure. As the nozzle diameter gradually increases, the actual boost ratio gradually decreases, and the peak pressure of the boost chamber further decreases. The nozzle diameter can no longer provide a load for the establishment of fluid pressure in the boost chamber. The results of this research provide a research basis for further controlling the pressure characteristics of the boost pulse water jet.

Fabrication of flexible pressure sensor for human detection by direct-write printing concave surface

Flexible pressure sensor plays an important role in the field of human-computer interaction area due to its high flexibility and sensitivity. Convex surface of flexible electrodes provide an efficient way to enhance the sensitivity of flexible pressure sensors. However, facilely preparing controllable convex surface of flexible electrodes is still a challenge for obtaining high sensitive flexible pressure sensors. In this paper, direct-write print technique was utilized to prepare a concave structure surface with viscoelastic substrate, which could be used to prepare convex structure flexible electrode for fabricating highly sensitive flexible pressure sensors. Interaction between ink droplet and substrate was explored to generate a concave template, which could be controlled in spacing and diameter with printing spacing and nozzle diameter. Convex structure flexible surface could be prepared with the concave template, and then the convex structure flexible electrode could be realized with the evaporation of metallic silver on the surface. Furthermore, flexible pressure sensor was assembled with an interlocking structure by stacking two convex structure flexible electrodes in a face-to-face way, which could efficiently enhance flexibility and electrical property. The flexible pressure sensor presents a high sensitivity, a fast response/recovery time (<100 ms) and excellent flexibility (more than 10,000 cycles of bending), which could be applied in monitor physiological signals such as pulse detection, sound vibration, finger bending and so on. Therefore, this work provides an efficient method for preparing controllable structured surface, which has a great potential in the fabrication of flexible sensors, wearable electronics and energy devices.

Study on the mechanism of soil erosion by submerged water jet vertical scouring in cohesive soils

The water jet trenching technique is widely used in the burial of submarine pipelines. However, its application in cohesive soils often leads to complexity in trench morphology and challenges in predicting trench dimensions due to unclear soil erosion mechanisms. These issues significantly impact pipeline burials. To investigate the soil erosion mechanism of water jet trenching in cohesive soils, two-dimensional physical simulation experiments of submerged vertical water jet erosion were conducted. The influence of jet pressure, impingement height, and nozzle diameter on the shape of the scour hole was analyzed. The erosion damage patterns of water jets on cohesive soils were studied, and a theoretical model for the development of scour holes was established. The study revealed that when the jet velocity reaches 1000 m/s and the nozzle diameter reaches 1 mm, a contracted neck forms at the upper part of the scour hole. The appearance of the contracted neck is due to excessive jet impact energy causing impact shear failure in the soil. The effective height and width of the contracted neck increase with jet pressure and nozzle diameter and decrease with impingement height. Based on Prandtl's bearing capacity model, a model for predicting impact shear failure in cohesive soils was established, and a predictive formula for the effective height and diameter of the neck was proposed. Experimental validation confirmed the accuracy of the predictive formula. These findings provide theoretical support for the application of water jet trenching techniques in cohesive seabed soils.

Parametric study of a vortex-enhanced supersonic inductive plasma torch

The feed gas injection configuration in radio-frequency (RF) inductively coupled plasma (ICP) torches plays a critical role in discharge stability, gas heating, and device thermal management: particularly if a supersonic nozzle is used to subsequently accelerate the hot gas. A novel injection configuration is the bidirectional vortex, which segments the internal ICP flow field into two counter-propagating vortices that can significantly enhance gas heating and reduce heat losses. The diameter of the interface between the vortices (known as the mantle) is expected to be an important dimensional parameter affecting torch operation, especially relative to the nozzle size. In this work, we investigate the effect of nozzle throat diameter on the behaviour and performance of a vortex-enhanced supersonic ICP torch. The system is operated at RF powers and argon mass flow rates between 200–1000 W and 0–400 mg s−1 respectively, and different nozzle diameters ranging from 1.5 to 4 mm are explored. Because of the high-temperature environment, and to prevent disruption of the vortex flow fields, non-invasive diagnostics are used to measure the gas temperature and plasma density, and to infer the torch thermal efficiency and achievable gas specific enthalpy change. The maximum temperature is between 8500–9500 K with the 1.5 mm nozzle giving the highest temperature for a given power and mass flow rate, while plasma densities vary between 1020–1021 m−3 depending on the operating conditions. The thermal efficiency increases from 29% for the 1.5 mm nozzle to just above 70% for the 4 mm nozzle with a similar maximum specific enthalpy of around 1.5 MJ kg−1. These results demonstrate the important coupling between torch properties, and how system optimization can lead to tailored performance of potential interest to several ground and space-based applications.

Utilization of RESOLV with polymer to produce prazosin hydrochloride nanoparticles and optimization of the process parameters

In this study, rapid expansion of a supercritical solution into a Liquid Solvent (RESOLV) was used for the first time to produce pharmaceutical nanoparticles of Prazosin hydrochloride (PRH). The Taguchi method (robust design) was utilized to design the experiments and ensure obtaining the optimal process conditions. The pressure (15–25 MPa), temperature (308–328 K) and nozzle diameter (300–700 μm) effects on the morphology and size distribution of the resulting particles were also examined. The size of the particles decreased from about 40 μm to the range of (252–418 nm). FTIR, DLS, FESEM, XRD, DSC were used to characterize the primary and processed PRH particles. According to DSC investigations, RESOLV-produced PRH showed lower crystallinity than original PRH.

Numerical analysis of electrohydrodynamic printing under electric field focusing mode

As an emerging micro/nanoscale 3D printing technology, Electrohydrodynamic (EHD) printing has undergone rapid development in recent years. However, in most EHD printing processes, voltage is directly applied to both the nozzle and the substrate, resulting in the electric field being influenced by the printing height. This poses challenges for printing three-dimensional curved surface structures. This study presents a comprehensive investigation into the EHD jetting process, utilizing a novel voltage loading method that separates electrodes from both the nozzle and the substrate. Through experimental setups and numerical simulations, this research was conducted to examine the effects of printing height, voltage, and electrode diameter on jetting behavior. The results show that compared to the traditional electrode form, the new voltage loading method will increase the electric field intensity of the liquid surface before ejection by 37.1% and is more conducive to the formation of Taylor cones. It can ensure that the printing fluctuation is less than 2.4% when the printing height varies between 1.5–2.5 times the nozzle diameter, which is more favorable for printing multi-layer structures. The threshold voltage for ejection is provided in this model. When the electrode is reduced, the efficiency of electric field utilization will be further improved, but the acceleration of the jet velocity will cause an increase in droplet size. The findings highlight the method’s capability to maintain consistent droplet sizes and electric field intensities across varying conditions, thereby enhancing printing stability and efficiency. The study’s innovations provide valuable insights for advancing micro/nano 3D printing technologies, emphasizing the potential for improved EHD printing processes in practical engineering applications.

Thermal Analysis of Photovoltaic Panel Cooled by Electrospray Using Different Fluids

In this study, the cooling performance of the photovoltaic (PV) panel was examined by the electrospray cooling method. The experiments were carried out under 1000 W/m² irradiation, 25 G nozzle diameter and 70 mm nozzle-to-PV panel distance and 20 kV voltage. Water, ethanol and water - ethanol (50%- 50%) mixture were atomized and sprayed on the panel surface at flow rates of 50-80-110 ml/h. The results showed that electrical power output decreased with increasing PV panel surface temperature. Ethanol and water - ethanol mixture showed a more effective cooling performance than water, especially at flow rates of 80 and 110 ml/h. At the highest flow rate, ethanol reduced the panel temperature by 59%, providing 6,8% more electrical power output than the uncooled condition. These findings show that the electrospray cooling method is effective in increasing the electrical efficiency of PV panels and that better cooling performance is achieved with ethanol, water - ethanol mixture compared to water.

Fabrication of Shape‐Controlled Copper Line Arrays by Meniscus‐Confined 3D Microprinting on Insulating Substrates

Meniscus‐confined electrodeposition (MCED), as a 3D printing process, exhibits excellent capabilities in microstructure fabrication. However, it faces numerous challenges, particularly when integrating with different substrates, especially insulating ones and cross‐layer interconnection. This study intends to investigate the impact of factors such as nozzle diameter, flight height of the nozzle over insulating substrates, and applied current by MCED on micro/nanoscale metal structures, to fabricate shape‐controllable and nanogap copper lines. As the flight height of the nozzle increases, there is no significant variation in the line height (≈60 nm) or width (≈15 nm) of the printed copper lines. And copper lines are successfully fabricated with consistent feature size oversteps totaling 1.2 μm in height. Additionally, highly dense copper line arrays are fabricated, achieving a minimum wire spacing of 120 nm. Remarkable stability and simplicity are realized in producing high‐resolution copper microstructures, demonstrating an acceptable degree of variability in insulating substrates and promising applications in integrated microsystems.

Dynamic Simulation Model and Performance Optimization of a Pressurized Pulsed Water Jet Device

Pulsed water jet technology has broad application prospects in the field of rock breaking. The pressurized pulsed water jet (PPWJ) is a new type of pulsed jet that offers high-amplitude pressurization, variable pulse pressure and frequency, and a high energy usage rate. To achieve a more destructive and powerful pulsed water jet, a dynamic simulation model of the device was established by using the AMESim software (v1400) based on the operational principle of PPWJs, and the simulation model was validated against the experimental results. The relationships between the key structural parameters of the PPWJ device and the pulse parameters were quantitatively investigated. The pulse pressure and frequency can be increased by appropriately increasing the nozzle diameter or boost ratio, and the pulse pressure will drop if the nozzle diameter or boost ratio exceeds a threshold value. Increasing the maximum displacement or action area of the piston will increase pulse length while decreasing pulse frequency; a proper match of the maximum displacement or action area of the piston will assure pulse peak pressure. The maximum outer diameter of the piston only affects the pulse frequency. The key structural parameters of the device were optimized on that foundation. Compared to the original device, the optimized device resulted in an increase in pulse frequency and jet output energy, leading to larger diameter and volume of erosion pits at the same stand-off distance and erosion time. The findings of this study offer valuable scientific insights for achieving efficient rock breaking with PPWJ.

Fabrication and Characterization of 3D Bioprinted Triple-layered Human Alveolar Lung Models.

The global prevalence of respiratory diseases caused by infectious pathogens has resulted in an increased demand for realistic in-vitro alveolar lung models to serve as suitable disease models. This demand has resulted in the fabrication of numerous two-dimensional (2D) and three-dimensional (3D) in-vitro alveolar lung models. The ability to fabricate these 3D in-vitro alveolar lung models in an automated manner with high repeatability and reliability is important for potential scalable production. In this study, we reported the fabrication of human triple-layered alveolar lung models comprising of human lung epithelial cells, human endothelial cells, and human lung fibroblasts using the drop-on-demand (DOD) 3D bioprinting technique. The polyvinylpyrrolidone-based bio-inks and the use of a 300 mm nozzle diameter improved the repeatability of the bioprinting process by achieving consistent cell output over time using different human alveolar lung cells. The 3D bioprinted human triple-layered alveolar lung models were able to maintain cell viability with relative similar proliferation profile over time as compared to non-printed cells. This DOD 3D bioprinting platform offers an attractive tool for highly repeatable and scalable fabrication of 3D in-vitro human alveolar lung models.

Numerical simulation of cavitating flow in liquid Nitrogen through a convergent nozzle

This research has dealt with the simulation of liquid nitrogen cavitation inside a convergent nozzle. This is important in cryogenic industrial applications. So in this study, computational fluid dynamics methods have been used for simulating the cavitation phenomenon. The Two-phase model in this research has been a hybrid/mixed model. Also, k- ε turbulence model has been employed in realizable state. For meshing the nozzle geometry, Gambit software has been used, while for numerical simulation, Ansys Fluent software has been employed. For simulation of cavitation, Schnerr and Sauer cavitation model has been utilized. This research has also examined the effect of changing the nozzle outlet diameter and the impact of changing the pressure difference in the inlet and outlet of the nozzle on the cavitation. As a novelty and unlike what would have been expected based on the Bernoulli effect, the results obtained from the simulation showed that the increase/decrease in the nozzle's outlet diameter resulted in an enhanced/diminished extent of cavitation in the nozzle's outlet region. Also, the increase/decrease of the pressure difference in the input and output of the nozzle would lead to a higher/lower extent of cavitation. This research also found that the effect of altering the nozzle's outlet diameter on the extent of cavitation has been far higher than the effect of changing pressure difference in its inlet and outlet. The results also indicated that upon reduction of the nozzle's outlet diameter from the base state (1.02 mm) by 10, 20, 30, 40, and 50 %, the volume fraction of the vapor diminished by 22.23, 43.029, 60.66, 74.73, and 87.16 % respectively. Finally, with the increase in the nozzle's outlet diameter from the base state (1.02 mm) by 10, 20, 30, 40, and 50 %, the volume fraction of the vapor increased by 26.83, 55.27, 84.47, 117.12, and 149.31 % respectively.

Re-investigation on effect of equivalent diameter of the conical nozzle on cluster size

Based on the Hagena scaling law, the cluster size in a gas jet is dependent on the equivalent diameter of a conical nozzle. In this work, the effect of the equivalent diameter deq of a conical nozzle on cluster size is separated into the individual effects of the throat diameter d and the half-opening angle α by comparing the Rayleigh scattering signals from gas jets. Nine types of conical nozzles with three different throat diameters (0.3, 0.5, and 0.7 mm) and three different half-opening angles (8.5°, 14.0°, and 24.2°) are used to produce argon gas jets at gas backing pressures from 10 up to 80 bar. The experimental results show that the effect of the throat diameter d is almost the same as that expected by the scaling law. However, the scaling law overestimates the effect of the half-opening angle α. The result is helpful for the precise characterization of cluster size and further understanding the interaction between intense laser and gas clusters.

OPTIMISATION OF A NEEM OIL BASED MINIMUM QUANTITY LUBRICATING (MQL) SYSTEM PARAMETERS FOR THE ORTHOGONAL MACHINING OF MILD STEEL

Cutting tools experience early failure and dimensional variation due to the high temperature developed during machining. Conventional cutting fluid applications do not successfully remove heat because they do not reach the chip-tool contact. Operators on the work floor may experience the adverse side effects of cutting fluids, such as skin and respiratory issues. As a result, a different lubricating method is necessary for machining without harming the tool-workpiece, which would also be advantageous for health and the economy. This research aims to develop and evaluate the efficiency and optimization of minimal use of Neem seed oils as lubrication for the Taguchi L9 array-based design for machining of mild steel. The Taguchi optimization technique was used to examine the impact of the neem oil based Minimum quantity lubrication (MQL) system (with flow rate, air pressure and nozzle diameter as factors) on the workpiece temperature and chip thickness ratio at cutting speeds of 260 rpm and 470 rpm. The outcome demonstrated that optimal settings at 260 rpm were a flow rate of 50 ml/hr, air pressure of 1.5 bars, and nozzle diameter of 0.8 mm for workpiece temperature, and a flow rate of 100 ml/hr, air pressure of 1 bar, and nozzle diameter of 0.8 mm for chip thickness ratio. At 470 rpm, optimal settings for workpiece temperature were a flow rate of 50 ml/hr, air pressure of 1.5 bars, and nozzle diameter of 0.5 mm, while chip thickness ratio optimization indicated a flow rate of 100 ml/hr, air pressure of 1 bar, and nozzle diameter of 0.5 mm.

Study on the key parameters of ice particle air jet ejector structure

Existing ice particle jet surface treatment technology is prone to ice particle adhesion during application, significantly affecting surface treatment efficiency. Based on the basic structure of the jet pump, the ice particle air jet surface treatment technology is proposed for the instant preparation and utilization of ice particles, solving the problem of ice particle adhesion and clogging. To achieve efficient utilization of ice particles and high-speed jetting, an integrated jet structure for ice particle ejection and acceleration was developed. The influence of the working nozzle position (Ld), expansion ratio (n), and acceleration nozzle diameter ratio (Dn) length-to-diameter ratio (Ln) on the ice particle ejection and acceleration was systematically studied. The structural parameters of the ejector were determined using the impact kinetic energy of ice particles as the comprehensive evaluation index, and the surface treatment test was conducted to verify the results. The study shows that under 2 MPa air pressure, the ejector nozzle parameters of n = 1.5, Dn = 4.0, Ld = 4, and Ln = 0 mm can effectively eject and accelerate the ice particles. The aluminum alloy plate depainting test obtained a larger paint removal radius and resulted in a smoother aluminum alloy plate surface, reducing the surface roughness from 3.194 ± 0.489 μm to 1.156 ± 0.136 μm. The immediate preparation and utilization of ice particles solved the problems of adhesion and storage in the engineering application of ice particle air jet technology, providing a feasible technical method in the field of material surface treatment.

АВТОМАТИЧЕСКИЙ СПОСОБ КОНТРОЛЯ ИЗНОСА СОПЛА FDM 3D-ПРИНТЕРОВ

To automatic control the FDM 3D-printer’s nozzle wear during printing, a device has been proposed for contractually measuring the actual nozzle diameter in the range from 0.2 mm to 1.2 mm.

Bound metal deposition of stainless steel 316L: Effect of process variables on microstructural and mechanical behaviors

The influence of printing variables on microstructural and mechanical behaviors on the 316 L stainless steel (316 L SS), produced via an additive manufacturing process, named as bound metal deposition (BMD), was investigated in this study. The printing parameters varied were infill density, diameter of the nozzle, and thickness of layers, which dictate the mechanical properties, surface roughness, and crack morphology of the samples. Based on the experimental investigation, it was found that the tensile properties were increased when the nozzle diameter and infill density were higher. The highest obtained ultimate tensile strength (UTS) was 402 ± 17 MPa, where the sample was fabricated with the following parameters: 0.40 mm nozzle diameter, 25% infill density, and 0.10 mm layer. The influence of the nozzle diameter also impacted the surface roughness, where a worse surface finish was noticed for the larger nozzle diameter.