The design of pipe network systems can on often represent a challenging and time-consuming task and depending on the design methods used, can often be error-prone. Choosing a suitable software tool can help expedite the design process significantly whilst simultaneously giving the designer confidence in the developed system since any potential design errors or troublesome operating conditions can be identified and eliminated rapidly during the initial design stage.
FluidFlow software helps us rapidly develop an efficient and economic whole-system design whilst also eliminating potential errors through prompts which are automatically enunciated during the calculation stage. This helps identify and focus on key components in the system and optimize the system design and operating conditions. The net result is an efficient system design which helps with economic considerations.
FluidFlow software includes in-built technology to help engineers automatically size networks. This includes piping and associated equipment. There is no requirement to procure a separate calculation module or product. Equipment which can be automatically sized includes pressure and flow control valves, orifice plates, pumps, fans, relief valves, bursting discs to name a few. The software includes various design options which you can use to auto-size your equipment. If we consider pipes, for instance, there are three sizing options available, design velocity, design pressure gradient, and economic pipe sizing. The latter option takes into account system operating frequency, operating costs, maintenance costs, etc. We can, therefore, use these tools to make an economic pipe selection for our system.
The following is an example of a fire hydrant which by using FluidFlow, was designed and modeled rapidly and the in-built auto-sizing technology used to size the network piping and components.
The initial requirements included the following:
A) Develop a detailed model of the proposed new fire hydrant system including the pump house equipment based partly on Figure 1.
B) Model the system in order to establish the flow distribution through the system when only five hydrants are in operation simultaneously. Note, the system comprised a total of 42 hydrants with a total pipe length of 3256 m.
C) Automatically size the diesel and electric pumps for the system and determine the nett positive suction head available (NPSHa) for the pumps.
D) Model a proposed vendor pump in the system with the view to establishing the duty operating point, power requirement, efficiency and compare the NPSHa vs NPSHr.
E) Automatically size all pipes in the system giving due consideration to the design maximum velocity limits noted in the NFPA guides (20 ft/s etc).
F) Model the entire system using different pipe materials i.e. PVC & steel piping to determine the overall effect on pressure losses, flow rates, etc.
G) Model the system based on a 2.5 inch AVK fire hydrant. The hydrant pressure loss data was added to the FluidFlow component database to enable this specific hydrant to be modeled in this system.
In addition to the above listed requirements, consideration was also given to the discharge nozzle diameter and different sizes were modelled. As we can expect, this had an effect on the calculated K value for the nozzle.
When analysing the system performance, consideration was also given to the resistance downstream of the hydrant, i.e. the resistance from the connected fire hose, in this case a 100ft long 2.5 inch hose. The associated roughness value was therefore included in the overall system modelling analysis.
The illustration in Figure 2 provides an overview of the developed FluidFlow model.
The intended design flow rate required for each pump was 1500 usgpm which formed the basis for automatically sizing the pumps and pipes. All pipes were auto-sized based on a design velocity and the closest standard pipe size selected on this basis. The pump duty pressure rise and NPSHa was also established and a pump vendor then made an initial pump selection based on the duty-point established by FluidFlow. This pump model which was then added to the FluidFlow pump database and modelled in the system.
The pump curves shown in Figure 3 provide a detailed illustration of the calculated operating point for both the duty and standby pumps as modelled in FluidFlow. The duty-point result match that of the pump vendor, i.e. 1500 GPM with a head requirement of 148 m fluid, power requirement of 205.9 kW and efficient of 66%. This initial result was based on a pump speed of 1780 RPM.
In this specific design case, once the model layout was developed in FluidFlow, the network could then be automatically sized. A key benefit of this overall whole-system design approach was that any potential troublesome operating conditions were quickly identified and eliminated. This system design was developed rapidly in FluidFlow saving the designer considerable time and project cost.
The FluidFlow software team recognise what tools a designer needs to help develop system design efficiently, and rapidly. As such, the standard product includes network sizing technology, a database of piping and equipment, heat transfer and the ability to model different fluid phase states all from within one single integrated user environment. There is no need to procure additional add-on modules or products.
The use of the in-built network sizing technology has been proven by our users to reduce design-time significantly.
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