Variable Speed Pumping Systems

Michael Tobias
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    Chicago is well-known for its majestic skyline and beautiful buildings. Aesthetics aside, there are plenty of reasons to celebrate the skyscrapers in the city. More and more, green building operations are becoming the norm in big cities across the United States and all over the world. Chicagoans will be proud to know that the city recently received top-level certification for its green buildings and sustainability efforts. It is, in fact, only the seventh city in the world to have been granted such a title.

    One thing that has helped the Second City earn this status is the increasing popularity of variable speed pumping systems. Pumps are impressively efficient machines for the most part. However, its high level of efficiency has also made it easy to dismiss the benefits that come with an optimal pumping system. As a rule of thumb: if the system in your building does not run at a constant speed, neither should the motors. There are multiple benefits to switching to a more energy-efficient system and this article will expound on these features.

    How It Works

    A pump allows the conversion of mechanical energy into pressure energy. In the traditional setup, pumps function at a fixed speed and control is exercised with the use of a throttling valve. Constant attention is required when it comes to regulating the output. This is not necessary for variable speed pumps, however.

    This kind of pumping system adjusts the output accordingly. If the system needs less water, it will automatically deliver less water to meet the requirements. This provides the user an easier and more efficient way of controlling the system.

    Variable Speed Pumping System Configuration

    It is imperative to distinguish between the traditional setup and this innovative alternative. A typical variable speed drive system comes with a speed controller to adjust the pump motor speed. The flow is directly affected by the speed mode to which the motor is set. The pressure, meanwhile, can be computed as the square of the motor’s speed.

    The pressure transducer is a device that senses the line pressure of the supply and it subsequently sends this information to the drive control. Afterward, the transducer signal is interpreted and the drive control then sends a signal indicating the required speed to the pump motor.

    The motor experiences variations in speed in order to keep a constant line pressure. The water flow demand declines as the pressure in the system increase from the closing of mold temperature regulators, chiller condenser valves, and heat exchanger valves. At this point, the drive control lowers the motor speed in order to reduce the pressure and flow in the pump. On the other hand, the drive control escalates the motor speed when the line pressure goes below the set point.

    Advantages of Variable Speed Pumps

    The savings one can obtain by setting up a variable speed pump system goes beyond the financial sense. Below are the reasons why it is high time to participate in the city’s initiative towards sustainable building operations.

    1. Better Reliability

    Variable speed pumps typically function at speeds below the maximum capacity. This quality thus reduces the wear of the mechanical seals, ensuring improved durability and reliability in the long run. 

    1. Reduced Costs

    As previously mentioned, users will likely enjoy a significant amount of energy savings when they make the switch to variable speed pumping systems. It is estimated that there will be as much as 50% reduced energy costs in situations where the pump is not constantly required. Moreover, the durability of the machines ensures fewer repair costs. 

    1. More Control

    The controller on variable speed pumps allows its user to monitor even the smallest variations in pressure and change the settings accordingly. This feature also lessens the likelihood of sudden flow or pressure changes as it is more precise than regular pumping systems.

    1. Improved Performance

    Since the inefficiencies caused by human error will be reduced, there will be a significant increase in performance. Fluctuations will be minimized and work pressure will be better distributed throughout the system.

    Disadvantages of Variable Speed Pumps

    While variable speed pumping systems offer numerous advantages, there are also several important considerations that should be taken into account. The following qualities might impact the decision to make the switch so read carefully.

    1. Structural Resonance

    Resonance might cause excessive vibration and this can potentially harm both the equipment and the environment. Structural vibration issues might occur in the pumps, piping, and support structure. These are not typically found in fixed-speed pumping systems thanks to the consistency of the output. Luckily, this problem can be easily remedied with the use of several products. 

    1. More Expensive Upfront

    The inverter drive and variable speed pumps required by the setup increases the complexity of the installation process. The procedure thus requires the services of a specialist and this is why it is typically costlier than the fixed counterpart. On the bright side, this additional fee will be overshadowed by the system’s long-term cost-cutting features. It will not take long before the initial extra cost is recouped by the savings generated in the setup.

    End Notes

    A building with a variable speed pumping system joins the rank of iconic structures like the timeless Merchandise Mart and the contemporary 340 on the Park. These two make up only a fraction of Chicago buildings that have already committed their efforts to LEED (Leadership in Energy and Environmental Design). There is no longer any excuse as the prices to convert to LEED-certified systems have gone down as the contractors and designers become familiar with sustainable buildings.

    Variable speed pumping systems might not be flawless, though the several drawbacks are easy enough to address and resolve. In times of environmental crisis, it is the responsibility of architects, designers, and building owners to support sustainable building methods. By adapting systems like these, Chicago continues its legacy as a leader in the global sustainability movement and paves the way for high-quality and resource-efficient structures for the future generations.

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    Tags : variable speed pumping system pressure energy

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