Although blowers are commonly used in manufacturing, it can be difficult to find good sources of information on the different types of blowers and how to choose the appropriate one. The purpose of this article series is to give a good, basic understanding of the different types of blowers and provide you with the technical information required to make a good decision for your application.
Recommended Reading What are the different types of blowers?
At its most basic level a blower is a tool that draws in air at an inlet and pushes air out as a steady stream at the outlet. Blowers can largely be classified into two categories: impeller based and positive displacement. Impeller based blowers have fins that radiate outwards from a rotating central axis. Positive displacement blowers use a mechanism of filling and emptying chambers at the inlet and outlet, respectively, to create flow. The fundamental difference between the two is that impeller based blowers have output flow that varies with pressure whereas positive displacement blowers have a more constant output flow less affected by changes in operating pressure.
Specialty Blowers
When an environment is unusually harsh—such as explosive, corrosive, or hot environments—a normal blower design must be adapted in order to operate safely.
Although blowers are commonly used in manufacturing, it can be difficult to find good sources of information on the different types of blowers and how to choose the appropriate one. The purpose of this article series is to give a good, basic understanding of the different types of blowers and provide you with the technical information required to make a good decision for your application.
Recommended Reading What are the different types of blowers?
At its most basic level a blower is a tool that draws in air at an inlet and pushes air out as a steady stream at the outlet. Blowers can largely be classified into two categories: impeller based and positive displacement. Impeller based blowers have fins that radiate outwards from a rotating central axis. Positive displacement blowers use a mechanism of filling and emptying chambers at the inlet and outlet, respectively, to create flow. The fundamental difference between the two is that impeller based blowers have output flow that varies with pressure whereas positive displacement blowers have a more constant output flow less affected by changes in operating pressure.
Although blowers are commonly used in manufacturing, it can be difficult to find good sources of information on the different types of blowers and how to choose the appropriate one. The purpose of this article series is to give a good, basic understanding of the different types of blowers and provide you with the technical information required to make a good decision for your application.
Recommended Reading What are the different types of blowers?
At its most basic level a blower is a tool that draws in air at an inlet and pushes air out as a steady stream at the outlet. Blowers can largely be classified into two categories: impeller based and positive displacement. Impeller based blowers have fins that radiate outwards from a rotating central axis. Positive displacement blowers use a mechanism of filling and emptying chambers at the inlet and outlet, respectively, to create flow. The fundamental difference between the two is that impeller based blowers have output flow that varies with pressure whereas positive displacement blowers have a more constant output flow regardless of change in pressure.
2. Positive Displacement Blowers
Positive displacement blowers create flow by filling and emptying chambers of air; these blowers produce flow which is relatively independent of operating pressure. There are several variations available which use the same premise but slightly different design. Here we discuss two popular types: rotary vane and rotary lobe.
Although blowers are commonly used in manufacturing, it can be difficult to find good sources of information on the different types of blowers and how to choose the appropriate one. The purpose of this article series is to give a good, basic understanding of the different types of blowers and provide you with the technical information required to make a good decision for your application.
What are the different types of blowers?
At its most basic level a blower is a tool that draws in air at an inlet and pushes air out as a steady stream at the outlet. Blowers can largely be classified into two categories: impeller based and positive displacement. Impeller based blowers have fins that radiate outwards from a rotating central axis. Positive displacement blowers use a mechanism of filling and emptying chambers at the inlet and outlet, respectively, to create flow. The fundamental difference between the two is that impeller based blowers have output flow that varies with pressure whereas positive displacement blowers have a more constant output flow regardless of change in pressure.
1. Impeller based blowers
There are two main categories of impeller based blowers: centrifugal and regenerative. Each has different characteristics which lend themselves to different applications; but they both have output flow that vary greatly with changing operating pressure.
Closed-Loop Vs Open-Loop Control Systems Part 3 of 3: When Open-Loop is the Correct Choice4/20/2018
In a previous article, Temperature Control of Air Heaters, we provided a general overview of control for process heat systems and explained the difference between closed- and open-loop controls. Briefly, a closed-loop system is output driven; the output of the system is continually measured and fed back to control components which adjust the operation of the tool to bring its output into alignment with a pre-set target. An open-loop system has no feedback loop and, as a result, the output of the tool does not impact its continued operation. For example, in a closed-loop process heat system if the inlet air increases in temperature the tool output temperature will briefly increase before the control system brings it back to setpoint, however in an open-loop system the tool output temperature will increase and no corrective action will occur.
In this article series we will expand on this topic, exploring when it is advantageous to use a closed-loop system and when it is acceptable to use an open-loop system. The first installment looked at the benefits of automating your system, the second installment looked at developing a better understanding of your process. This third installment will look at when an open-loop system is a good choice for your application.
In a previous article, Temperature Control of Air Heaters, we provided a general overview of control for process heat systems and explained the difference between closed- and open-loop controls. Briefly, a closed-loop system is output driven; the output of the system is continually measured and fed back to control components which adjust the operation of the tool to bring its output into alignment with a pre-set target. An open-loop system has no feedback loop and, as a result, the output of the tool does not impact its continued operation. For example, in a closed-loop process heat system if the inlet air increases in temperature the tool output temperature will briefly increase before the control system brings it back to setpoint, however in an open-loop system the tool output temperature will increase and no corrective action will occur.
In this article series we will expand on this topic, exploring when it is advantageous to use a closed-loop system and when it is acceptable to use an open-loop system. The first installment looked at the benefits of automating your system. This second installment will look at an important secondary benefit that emerges from using a closed-loop control system: developing a better understanding of your process. Know Your Operating Parameters
Open-loop systems are often controlled using a percentage power setting (i.e., setting the dial on the tool to 6 out of 10). This is because without a feedback system, there is no way to verify if it has reached a target temperature setpoint. If you are installing a closed-loop system for the first time, it is possible that you won’t know your exact target temperature for certain. This is normal and determining that temperature setpoint will be an important step during the commissioning of the system. Once established, there are considerable advantages to knowing your exact operating temperature.
In a previous article, Temperature Control of Air Heaters, we provided a general overview of control for process heat systems and explained the difference between closed- and open-loop controls. Briefly, a closed-loop system is output driven; the output of the system is continually measured and fed back to control components which adjust the operation of the tool to bring its output into alignment with a pre-set target. An open-loop system has no feedback loop and, as a result, the output of the tool does not impact its continued operation. For example, in a closed-loop process heat system if the inlet air increases in temperature the tool output temperature will briefly increase before the control system brings it back to set point, however in an open-loop system the tool output temperature will increase and no corrective action will occur.
In this article series we will expand on this topic, exploring when it is advantageous to use a closed-loop system and when it is acceptable to use an open-loop system. This first installment will look at the benefits of automating your system with closed-loop control and the process issues that this can help resolve. Process Precision
If your application has tight tolerances and temperature requirements, then it will likely require a closed-loop control system. Including a feedback loop in your control scheme will ensure that you are getting the temperature you need, where you need it. Closed-loop control greatly increases the accuracy of a process heat system as the output is constantly being measured and adjustments are being made when necessary to keep the output on target.
A heat/shrink tunnel, is an enclosed and heated area that is used to not just apply heat to an object, but create a heated local environment around said object. Heat tunnels are generally found above or enveloping a section of conveyor belt to allow for automated travel through the tunnel. The most common use for a heat tunnel is the activation of heat shrink labels, packaging, and tamper bands on a container; however, they are also used to cure paints and heat parts. This article series will cover the most common types of heat tunnels available, their advantages and disadvantages, and the technical complications of heat shrinking. Be sure to read parts one and two of this series before proceeding.
Technical Complications of Heat Shrinking
For the majority of applications, applying a shrink label to packaging is not as straightforward as simply passing the container through an off-the-shelf heat tunnel. There are a multitude of factors that complicate the heat shrinking process. Taking time to consider these factors is important to designing a successful and robust system.
Shrink Label Material
The most common shrink materials are PVC, PETG, and PLA. The choice of material can greatly change the requirements for, and effectiveness of, a heat tunnel. These materials shrink because, during manufacturing, they are stretched until their polymer chains are almost aligned; this is an unnatural state. When heat is applied these materials revert to their natural, tangled state resulting in their shrinking.
PVC tends to be the cheapest and easiest material as it shrinks at a lower temperature and more evenly when heat is applied. PVC typically has an amorphous structure which means that it shrinks uniformly without localized areas of distortion and is less likely to wrinkle. It also has good scuff resistance. However, PVC is less environmentally friendly than other plastics and will contaminate recycling streams when mixed with dissimilar plastics.
A heat/shrink tunnel, is an enclosed and heated area that is used to not just apply heat to an object, but create a heated local environment around said object. Heat tunnels are generally found above or enveloping a section of conveyor belt to allow for automated travel through the tunnel. The most common use for a heat tunnel is the activation of heat shrink labels, packaging, and tamper bands on a container; however, they are also used to cure paints and heat parts. This article series will cover the most common types of heat tunnels available, their advantages and disadvantages, and the technical complications of heat shrinking. Be sure to read part one of this series before proceeding.
Advantages and Disadvantages
Most technologies have ideal areas of application which relate directly to their strengths and weaknesses. The following is a summary of the strengths and weaknesses of the three types of heat tunnels discussed.
Infrared Tunnels
Advantages
A heat/shrink tunnel, is an enclosed and heated area that is used to not just apply heat to an object, but create a heated local environment around said object. Heat tunnels are generally found above or enveloping a section of conveyor belt to allow for automated travel through the tunnel. The most common use for a heat tunnel is the activation of heat shrink labels, packaging, and tamper bands on a container; however, they are also used to cure paints and heat parts. This article series will cover the most common types of heat tunnels available, their advantages and disadvantages, and the technical complications of heat shrinking.
Types of Heat Tunnels
The type of heat tunnel is determined by the heat source used. Common heat sources include infrared, steam, and hot air. Regardless of the type, all heat tunnels work by transferring energy from a heat source to an object within an enclosed area. The goal may be to a shrink film/label, cure a coating of paint, remove excess water/moisture, or any other application requiring immersion in heat but the principals remain the same. The amount of energy transferred depends on the output capacity of the heat source, the material being heated, and the residence time of the object in the tunnel.
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