The design of suspension mixing tanks is often embedded in empiricism due to insufficient understanding of the hydrodynamics of dense solid-liquid interaction. This is particularly limiting during the design of mixing tanks or batch reactor for expensive high quality products in the fine chemicals, biological and pharmaceutical processing industries. In this paper, a computational fluid dynamics (CFD)-assisted design approach has been employed to study the effectiveness of mixing tank geometrical configurations to suspend particles. Ten crucial variables were investi-gated and the effects of changing the value of these variables were documented. In addition, a multivariable study involving these ten variables was also conducted to investigate the most im-portant variables among them. Finally, by capturing the essence of the results, a design heuristic was developed which can be applied across the process industry.


A pressure relief valve protects process equipment from the hazards of high (or low) pressure in a process. It operates by opening at a designated pressure and ejecting mass from the process equipment. The ejected mass contains energy - the removal of the energy reduces the process pressure. Sizing the pressure relief valve incorrectly may lead to undesirable results such as ejecting insufficient amount of mass as a function of time. 

This article, published by American Institute of Engineers (AIChE), provides an introduction to sizing a pressure relief valve. The article is provided for educational purpose only and readers are recommended to consult experienced professional engineers to conduct this task.


A chemical is a material that may pose a health hazard or physical hazard, and included compounds that are toxic, flammable or corrosive. Chemicals vary greatly in toxicity – some are highly toxic and can cause immediate or delayed symptoms, others are less toxic and pose a less immediate threat or no threat at all. Chemicals in a gas or liquid state generally lead to greater exposures than solid chemicals. A chemical weapon is a device or mechanism designed to deliberately deploy a harmful chemical. Chemical weapons use the toxic properties of chemical substances, rather than their explosive properties, to produce physiological effects on victims. The toxicity of the chemical, and its concentration when it reaches people, both determine the severity of the exposure. The concentration of a chemical in the air is determined by a range of variables, including:
- The volatility, state, vapour density and persistence of the chemical;
- The presence and strength of environmental factors (e.g. wind, rain, humidity); and
- The environment in which the chemical is released eg. enclosed spaces can expose people to more concentrated doses

Pressure Relief Valve - Jimmy Lea P/L


As one of the leading CFD consulting companies in Australia, Singapore and the Asia Pacific region, it is important that we demonstrate the accuracy of our simulation results. There are two computational fluid dynamics (CFD) journals in this folder. These CFD simulation - related journals can be downloaded simply by clicking the icon on the left, namely:

Lea J [2009], Suspension mixing tank-design heuristic, Chemical product and process modelling, Volume 4, Issue 1, Article 17, The Berkeley Electronic Press

Fort I [2009], Comments on Lea J [2009] “Suspension mixing tank-design heuristic” Manuscript 1419, Chemical product and process modelling, The Berkeley Electronic Press

In Lea [2009], a computational fluid dynamics (CFD)-assisted design approach has been employed to study the effectiveness of mixing tank geometrical configurations to suspend particles. In contrast, the paper Fort [2009] deals with the analysis, via physical experimentation, of the process characteristics of agitated system with a pitched blade impeller and radial baffles (impeller power input and impeller pumping capacity) under turbulent regime of flow of agitated batch.
Original experimental data are compared with results of CFD simulation in a pilot plant mixing system published in literature. These two papers concluded that the CFD results from Lea [2009] and experimental results from Fort [2009] are in good agreement.


There is a recurring number that despite magnificent developments in technical safety doesn’t seem to go away. That number is 80, and it relates to the percentage of incidents that in some way has been contributed to by a human. It is a recurring average across industry and in different settings. Looking on the bright side, it means that there is huge scope to make a significant improvement. So how can we reduce the rate at which people contribute to incidents? The first step is to recognise that human failure is not random, but systematically linked to the tasks that people perform, the equipment they use, and the characteristics of the work environment. By understanding these elements it is possible to reduce the potential for errors to occur in the first instance, or at least to pre-empt them so that when they do occur, they can be safeguarded against.

This article, published by The Chemical Engineer, provides an overview of human failure, the factors that contribute to it and the process by which the risks can be reduced.

Suspension Mixing Tank - Design Heuristic by Jimmy Lea P/L


The National Guidelines for Protecting Critical Infrastructure (CI) from Terrorism (the Guidelines) provide a framework for a national, consistent approach on the protection of CI from terrorism for the Australian, State  and Territory governments and business.  They are designed to aid owners/operators of  CI in their discussions with jurisdictions (including the Australian Government) about protecting CI from terrorism. The Guidelines recognise that the treatment of individual  
CI assets will depend on an assessment of  the criticality of the asset in question, the  nature of the security environment and the  risk profiles for that asset or relevant sector. 

All governments recognise that the threat of terrorism is enduring and requires sustained mitigation efforts. An intelligence-led, risk informed approach is required to develop adequate levels of protective security for Australia’s CI, minimal single points of failure, and rapid, tested recovery arrangements. Although governments have a role in the protection of CI, it is a matter of responsibility and good corporate governance that  owners/operators of CI address the security of their assets and continuity of their business.  Owners/operators of CI should consider terrorism as one of the hazards in an ‘all hazards’ risk management approach to their operations. Governments need to work with business to provide sufficient information on which  owners/operators can base their decisions. All jurisdictions regularly review their administrative and legislative arrangements to better address the terrorist threat.

Chemicals Weapon Guidelines for Crowded Places - Jimmy Lea P/L
AutoDesk Inventor Viewer - Jimmy Lea P/L
Chemicals of Security Concern - Jimmy Lea P/L


Security and blast considerations are most effectively incorporated during the design stages of a building. Key considerations include selection of site and understanding the environment and terrain; positioning and orientation of the buildings within the development; landscaping to create security buffer and provision of car parks and internal access roads within the development. Further considerations include the structural scheme, curtain walls and facades, locations of car parks, locations of critical assets and areas of mass congregation.

Incorporating physical security concepts into the initial architectural design of a project is the most efficient and cost-effective way to achieve the required security level. Apart from the financial benefits of early planning, by considering the security aspects from the onset enables architects and planners to work with security consultants to blend the required protection elements into the design of the facility to satisfy both security and aesthetic requirements.

This publication containing the guidelines for enhancing a building security in Singapore context has been prepared by Joint Operations Group - Singapore Ministry of Home Affairs.


Autodesk Inventor Viewer software (64-bit) can be downloaded from this site for your own use. This viewer displays 3-D graphics objects in an interactive window. This viewer is available under the terms of the license agreement included in the installation. To download, simply click on the icon of interest and follow the instructions accordingly.

Engineering Journals - Jimmy Lea P/L
Economic Pipe Diameter - Jimmy Lea P/L


Critical infrastructure is vital to the social wellbeing, economic prosperity, and environmental values of the people of New South Wales (NSW), Australia. NSW infrastructure needs to withstand the shocks of natural, technological, and malicious hazards to continue operating, be returned to service as soon as possible after any service disruption, and address long-term stresses such as climate change and population growth. The NSW Critical Infrastructure Resilience Strategy 2018 complements recommendations within the 2017 State Level Emergency Risk Assessment and the NSW State Infrastructure Strategy 2018-2038. It builds on previous work including the Commonwealth’s 2015 Critical Infrastructure Resilience Strategy and COAG’s National Strategy  for Disaster Resilience. 

This strategy is the result of a collaborative partnership between government, the NSW community, and infrastructure owners and operators. A dedicated working group, established by the State Emergency Management Committee, has coordinated a discussion paper and industry consultation sessions to produce this five-year strategy. It demonstrates the commitment of all parties to work together to build a strong and resilient NSW that can withstand, adapt and thrive when threatened by emergencies such as bomb blast of a building by terrorists.

Reduce Human Failure - Jimmy Lea P/L
Enhancing Building Security - Jimmy Lea P/L
National Guidelines for Protecting Critical Infrastructure - Jimmy Lea P/L


A large and diverse number of industrial, agricultural and veterinary chemicals are legitimately used by individuals and organisations every day throughout Australia.  However, some of these chemicals have been diverted from their lawful use for other purposes, including terrorist related activity. The Council of Australian Governments (COAG) has identified 96 chemicals that require priority risk assessment. The list of these chemicals, entitled Chemicals of Security Concern, can be downloaded by clicking on the icon.


When designing a pipeline or a piping network for process plants, care should be taken to ensure the pipe and equipment are sized correctly. Specifying an oversized pump whilst under sizing the pipe diameter may increase pump purchase and operating costs. In contrast, specifying an undersized pump coupled with an oversized pipe diameter will reduce pump related costs, yet increase the purchase and installation costs of pipes. The correct combination of pump and pipe diameter need to be specified to present the most economical piping system.

This article aims to demonstrate a calculation method to determine with reasonable accuracy the most economical pipe diameter, taking into consideration the installation cost of pipe and pump operating cost throughout its design life. This article is complimentary can be downloaded by clicking the icon on the left and follow the instructions accordingly.


ANSYS CFD Viewer software can be downloaded from this site for your own use. The ANSYS CFD Viewer displays 3-D graphics objects in an interactive window. This viewer is available under the terms of the license agreement included in the installation. To download, simply click on the icon of interest and follow the instructions accordingly.

CFD Viewer - Jimmy Lea P/L
Free Unit Converter - Jimmy Lea P/L


Feel free to download a copy of our engineering unit converter software for your own use. This software is very comprehensive in regard to the number of units it can convert and we provide it free-of-charge, free from malware, advertisement and royalty. To download, simply click on the icon of interest and follow the instructions accordingly. This unit conversion software free download and any support from Jimmy Lea P/L are provided "AS IS" and without warranty, express or implied.

By downloading this software, you agree that Jimmy Lea P/L disclaims any implied warranties of merchantability and fitness for a particular purpose. In no event will Jimmy Lea P/L be liable for any damage, including but not limited to any lost profit, lost saving or any incidental or consequential damage, whether resulting from impaired or lost data, software or computer failure or any other cause, or for any other claim by the user or for any third party claim.

NSW Critical Infrastructure Resilience Strategy - Jimmy Lea P/L
Validation of CFD results using PIV - Jimmy Lea P/L


The manufacture of nitrocellulose, which is the basis of most artillery, rocket and missile propellant, is intrinsically risky due to the energetic nature of the product and the sensitivity of the process.  To optimise the performance of the nitration unit, computational fluid dynamics (CFD) was employed to characterise the nitration unit and to provide detailed, relevant process data emanating from a new perspective.  The actual nitration unit was scaled-down in order to use independent measurements from particle image velocimetry (PIV) to validate the CFD results.  It was only after the model and simulation results were successfully validated that the characterisation of the actual unit was carried out.  With the nitration unit characterised, its optimisation was carried out by performing modelling on different geometrical configurations with a view to selecting one which gives an optimum performance. 

Engineering & Simulation Consultants