Tag: control

EXAIR Cabinet Cooler Systems Control Humidity While Maintaining Internal Temperature

Published on by Neal RakerLeave a comment

As the weather in the Northern Hemisphere changes over from winter to spring and temperatures start to climb, it is slowly becoming necessary for customers to utilize the Cabinet Cooler Systems to keep control panels cool.

One such situation involved a customer who was building a panel for his client in Malaysia. Malaysia is about 3 degrees north of the Equator, so it is what I would call a semi-tropical if not tropical environment. And such places are quite high in humidity levels. This customer had a client who was in the palm oil processing industry which is quite big in Malaysia. He needed a Cabinet Cooler System to generate about 1000 Btu/hr. of cooling power in a NEMA 12 type system. So I recommended he go with a 1700 Btu/hr. Cabinet Cooler System so he had plenty of capacity. I also recommended he go with 24 VDC thermostat control so he could easily pull the power out from within his panel and not have to run any new circuits.

As the customer duly noted, the fact that the Cabinet Cooler System purges the cabinet with clean, cool and dry compressed air allows for the humidity levels to hang down at a much lower level around 40 – 50% RH instead of up around 80 – 90%. This is attributed to the processing and drying of the compressed air at the production point before it is sent out to the facility and again at the point of use with the included, 5 micron, compressed air filter/separator that comes with each system.

Previously, the customer was using only the small, DC type fans to pull that hot, humid air through the panel which led to many corrosion issues and did not relieve the heat issue at all. With this new improvement, the end user no longer has to worry about such issues. Also, there is virtually no maintenance for this system which produces much longer up-times for the customer as there are no moving parts to wear out. Overall, it was a good recommendation in this case as the Cabinet Cooler System was handling multiple, previously negative issues. Now the pain has been taken away and the end user can move on to solving other, more pressing problems.

Neal Raker, Application Engineer
nealraker@exair.com

EXAIR’s Electronic Flow Control Saves Air & Money

Published on by Brian FarnoLeave a comment

This past weekend I cleaned out some storage tubs that have been in my basement since I moved in.  Within these tubs and boxes were all of my notes from college, along with all of my text books.  Being any form of an engineering major means you keep all notes and books from college (I think).   Among them was the manual for my graphing calculator.  Even though I don’t graph anything on my calculator from college anymore, it still sits on my desk here and I use it to tell me how much money I am saving customers when they install our products.  Along with calculating which Cabinet Cooler System they need.

The truth is, I don’t even need the calculator on my desk when I am looking at how much money an EXAIR Electronic Flow Control can save a customer.  That’s because there is a free easy to use calculator right on our website.  This calculator is going to allow you to put in how much air you are using, the percent of time the unit is on, how much you paid for the EFC and the compressed air, then it gives you how much air and money you save.  The EFC Calculator will even tell you how many days it will take to recoup the price of the EFC.

opt_sakAPPillustr

Let’s look at an example of a 60″ Super Ion Air Knife that was installed to clean off bumper covers before a paint line.  Not only did the customer save money by using the Super Ion Air Knife rather than the drilled pipes, they saved additional air and money by turning the compressed air off when a bumper wasn’t present.   The following figures show the amount of money and air saved by implementing the EFC.

EFCp4

The Super Ion Air Knife was operated at 40 psig inlet pressure, this utilizes 102 SCFM of compressed air.

The process ran for 24 hours a day which equates to 1,440 minutes. There is a six second gap between each bumper, this means that you can reduce the on time by 37.5% just by turning the air off between bumpers.

The average cost to produce 1,000 SCF of compressed air is $0.25.  The calculator shows the results below which include the pay back time for the EFC purchase. (CLICK it for a larger image)

EFC Calc

As you can see, it will take a mere 84 days to reach a return on the investment of the EFC.  The chart below (CLICK to enlarge) shows the math and cost savings when you also account for the amount of air saved by using the Super Ion Air Knife.

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So if you have an intermittent compressed air application, by all means give us a call.   We’ll help you figure out how much you’ll save by installing the EFC.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Air Compressor Throughput Control

Published on by Lee Evans2 Comments

Throughput Control

At the end of my last blog, I mentioned the slide valve operation on a screw compressor.  A slide valve is the basis of throughput control for a screw compressor.  Throughput control is a term used to describe the process of controlling the energy input to the compressor in order to reach the control objective (output pressure and/or flow).  No matter the type of compressor, throughput control is achieved by using speed control, suction throttling, discharge throttling, or recycle control.  There are a few other methods of controlling throughput, but these four are the most common, and throughput control is a common practice used to dial in the needs of a compressed air system/application.

The first, speed control, is the most common and most efficient method.  Essentially, the output flow and pressure are regulated by adjusting the speed of the motor driving the compressor unit.  Increasing the speed of the motor driving the compressor will result in an increased output flow at a constant pressure, or an increased output pressure at a constant flow.  Speed control can also be coupled with other control methods to fine tune the throughput of the compressor.

Suction valve throttling is exactly what it sounds like.  The incoming air flow and pressure are restricted by installing a control valve immediately upstream of the compressor inlet, and the valve’s position is controlled as a function of the exhaust discharge pressure and/or flow.  When the valve is activated and the suction is “throttled” or restricted, the output flow will decrease (because there is less air taken in by the compressor), and the output pressure will subsequently increase.

Discharge valve throttling restricts the pressure from the compressor to match the process requirements at a constant flow.  As a result of this setup, the compressor must work harder than the process requires and this control scheme is extremely inefficient.

Recycle control uses a valve to return compressor discharge flow back to the suction port of the compressor.  As many people know, compressing a gas can generate a good amount of heat, and this heat is often transferred into the compressed air.  Because of this, a cooler is usually (and should be) installed in the line between the recycle control and the suction valves.  The recycle valve can modulate from fully open to fully closed, which gives a full range of control over the discharge flow and can help with loading/unloading of the compressor.

These control methods are all fairly straightforward and on their surface aren’t too intimidating.  They remind me of rudimentary PID controllers, which can be dialed in to a tee.   Think of the way an elevator car reaches the intended floor without slamming to a stop or jolting when it starts moving.  That’s achieved though PID control, and similar methodology is applied to compressor load and unload as well as operation.  But if I get under the surface of compressor control and see PID diagrams, I’m getting the professor!

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Super Air Knives Used To Deflect Fumes and Smoke from Furnace

Published on by Neal Raker1 Comment

One of our overseas distributors had an interesting application in a foundry. Their customer has a large furnace that opens at various times for a variety of reasons. When the furnace doors open, smoke and fumes come rolling out of the furnace. The customer has a large vent hood type system to aid in removal of these fumes and smoke. Unfortunately the vent does not capture all the smoke when released. So, the customer devised a plan to mount (4) model 110042SS 42” Stainless Steel Super Air knives onto large masts to get them up high enough to create a “ceiling” of air that would deflect the smoke into the vent hood for removal. Following are a couple of photos of the set up.

SAK2 sak1

Below is a photo of the control cabinet housing the filter and regulator equipment.

SAK3

Previously, the customer had nothing in place to assist the vent hood. Now they do and are quite happy with the result.  There were some small system adjustments that needed to be made, but once fully operational, the Super Air Knifes performed well to help reduce the overall pollution seen within the area.

Neal Raker, Application Engineer
nealraker@exair.com