Knowing many of you may be distracted by the thought of Mom’s (or Dad’s) home cooking – we would like to wish you all a Happy Thanksgiving! Enjoy any time off, and your families and friends.
Enjoy,
The EXAIR team
1-800-903-9247
Month: November 2016
Stretch Wrap Static Solution
Recently a customer called in to EXAIR to discuss a static issue in a stretch wrap process in the plant. Stretch wrap is a highly stretchable plastic film. The elastic recovery keeps the wrapped load tightly bound. The most common stretch wrap material is a linear low-density polyethylene or LLDPE. The combination of the stretching of the plastic film and the sliding of the film on the cardboard boxes as it is being wrapped causes a build up of static. This static can cause serious havoc and issues in the process including personnel shocks, zapping counters and other sensors causing failures, and preventing marking systems from delivering good information on to the stratch wrap.
The discussion started with minimum and maximum load sizes and how to design a system that would work with all configurations and be as flexible as possible. We spoke of dimensions and where we could we could mount on 3 sides, and so forth.
Then came the question that we invariably get to and that is ‘what issue does the static cause and how does it affect the rest of the process?’ The answer here simple, ‘an operator has to write a code number on the side and affix a label, and in doing so, receives a shock.’ When it was determined that only a small section of one side of the load needed to be treated, the solution was simple. We proposed an 18″ Ionizing Bar and Power Supply. Because the machine had a fixed datum, all loads would pass within 1-2″ of a vertically installed Ionizing Bar, so no adjustment is needed for different load sizes.
The Ionizing Bar quickly dissipates a strong static charge as shown in the chart below.
EXAIR offers many systems for total static control. When static is a problem on moving webs, sheet stock, three dimensional parts, extrusions or packaging, EXAIR has a solution.
To discuss your application and how an EXAIR Static Eliminator would help out, feel free to contact EXAIR and one our Application Engineers can help you determine the best solution.
Brian Bergmann
Application Engineer
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Twitter: @EXAIR_BB
A Glass Company Needed a Vortex Tube to Keep Their Pyrometer Reading Accurately
A glass company was using a pyrometer to measure the temperature of the glass. As with many instruments, it is important to keep the electronics cool for proper operations. In this case, they were having issues with the accuracy of the measurement. They contacted EXAIR for a solution.
With their pyrometer, it was designed with a “cooling” device already. This was basically compressed air that would blow around the instrument. Because of the surrounding area, the compressed air was heating up to 50 deg. C. This additional heat would not cool the pyrometer properly, and it was causing unreliable readings. He gave me the design specifications for cooling, and it was 40 liters per minute of compressed air at a maximum of 25 deg. C. I told him that we had the perfect solution to keep his instrument cool, and it is the EXAIR Vortex Tube. Vortex Tubes are a low cost, reliable, maintenance-free solution that uses compressed air to power the Vortex Tube to produce cold air as low as -46 deg. C. They thrive in remote locations, high temperature environments, and harsh conditions with little to no worry about maintenance (other than providing a source of clean air). With a range of cooling capacities from 135 BTU/hr to 10,200 BTU/hr, I was sure that we could meet the requirements for proper cooling.
To determine the correct size, I had to look at the temperature drop and the flow requirement. The Vortex Tube would have to decrease the incoming temperature from 50 deg. C to at least 25 deg. C. This would equate to a minimum temperature drop of 25 deg. C. With the chart below, I see that we are able to get a 29.7 deg. C temperature drop at a 70% Cold Fraction and 3 bar inlet pressure. EXAIR Vortex Tubes are very adjustable to get different outlet temperatures by adjusting the inlet pressure and the Cold Fraction. The Cold Fraction (CF) is the volume of cold air flow that will be coming out the cold end. By adjusting a screw on the hot end of the Vortex Tube, the cold flow can be change to the desired CF.
The other requirement was the amount of air flow, 40 SLPM (Standard Liters per Minute). In comparing the above information to the catalog data at 6.9 bar, we have to consider the difference in absolute pressures. With an atmospheric pressure of 1 bar, the equation looks like this:
VTflow = CAF/CF * (Catalog Pressure + 1 bar)/(Supply Pressure + 1 bar)
VTflow – Catalog Vortex Tube flow
CAF – Cold Air Flow
CF – Cold Fraction
Catalog Pressure – 6.9 bar
Supply Pressure – Chart above
From this equation, we can solve for the required Vortex Tube:
VTflow = 40 SLPM/0.7 * (6.9 bar + 1 bar) / (3 bar + 1 bar) = 112.9 SLPM.
In looking at the catalog information, this would equate to our model 3204 Vortex Tube which uses 113 SLPM of compressed air at 6.9 bar. So, after installing, the Vortex Tube was able to supply 20.3 deg. C air at a flow of 40 SLPM; keeping the pyrometer reading correctly and accurately.
Sometimes compressed air by itself is not enough to “cool” your instruments. The EXAIR Vortex Tubes can reduce the temperature of your compressed air to the desired requirement. If you believe that your measuring equipment is being affected by temperature, please contact an Application Engineer at EXAIR to find the correct product for you.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb
Conveying Plastic Chips Using Only Compressed Air
One of our distributors in Europe recently contacted me about an application to move plastic chips and pellets (shown above). In this application the customer needed to move the material 6m vertically (upward), 10m horizontally, and then 4m vertically (downward) at the fastest rate possible using an EXAIR Line Vac. So, we needed to determine the most suitable model number.
When determining the proper model Line Vac for pneumatic conveying applications, we investigate specifics such as:
Bulk density of the material
Shape/size of the material
Conveying distance
Conveying height
Required conveyance rate
Available compressed air supply
Using this information we can make a recommendation as to the best Line Vac for the application. For this application, the bulk density of the material was between 10-15 pounds per cubic foot, the size was relatively small, our distances were given, and the required conveyance rate was “as much as possible”. With a sufficient compressed air volume and pressure of 80 PSIG, we knew everything we needed to make a model number recommendation.
Due to the significant height as well as the considerable horizontal distance, the best solution for this application was a Heavy Duty Line Vac. Given the small size of the material, several options “could” move the chips/pellets, but we needed to determine which Line Vac would move the most volume. Our recommendation was to use the Heavy Duty 2” Line Vac, model 150200, which we estimate could move ~400 pounds per hour (or more) in this application.
Conveying materials pneumatically removes worker interaction with the movement of the product, allows for controlled ON/OFF cycling of material transfer, and eliminates fatigue related to physical handling of the material.
If these aspects could benefit your facility or application, contact an EXAIR Application Engineer.
Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE