The Check-veyor is a unique and revolutionary patented pneumatic conveying system based on the Series Flo concept designed and developed by Tech-Air, Inc. It consists of a Check Kleen diverter valve, Primary and Secondary Check Valve Assemblies (which include the Flap Check gates), a top and bottom Valve Chamber to house the Check Valve Assemblies, a Back Vent valve and a Check-Timer control panel. Series Flo utilizes the Check Valve Assemblies stacked on top of each other. A spacer insert can be added to increase the capacity of the valve.
The Check Kleen diverter directs air from a blower to the top or bottom valves using an adjustable cube timer. For discussion purposes, assume a system has an operating pressure of 10 PSI. When the air is directed through the Primary (top) Check Valve, the velocity of the air will close the gate, but what creates the seal is the differential pressure that is created between the Top Chamber and the surge hopper above it. The Top and Bottom Chambers (and the convey line) are pressurized to 10 PSI, while the vented surge hopper above is at essentially an atmospheric pressure. The Flap Check (top gate) is sealed tight, preventing product from entering the Top Valve Chamber. Any material that was in the Top Chamber is conveyed through the Secondary (bottom) Check Valve and into the product discharge line.
When the timer switches and air is blown into the Bottom Valve Chamber, the Flap Check on the Secondary (bottom) Valve Assembly is closed and the system air continues to move the product down the line. At the same time the blower air is directed to the Bottom Valve Chamber, the Back Vent valve is opened (since the Check Kleen diverter and Back Vent valve operate off the same timer), allowing any 10 PSI air that is still in the Top Chamber to be immediately vented into the surge hopper. When the pressurized air is vented out of the Top Chamber, the differential pressures required to seal the Bottom gate are created. Now the Bottom Chamber and convey line are pressurized to 10 PSI while the Top Chamber is at atmospheric pressure. The seal is broken on the top Flap Check, since there is no differential pressure between the Top Chamber and the surge hopper, allowing product to fill the Top Chamber (and any insert). When the air is directed to the Top valve, that chamber is pressurized again. The lower pressure in the surge hopper creates the differential pressure that seals the Top gate. This cycle is repeated continuously and can be adjusted as required to meet flow rates. Note that air going down the convey line during both cycles.
It is essential to provide
venting for the Check-veyor. The Flap Checks are opened and
closed due to a combination of the velocity of the air from the blower and the
pressure differential that is created between the chambers and the surge hopper
located above the Check-veyor. If one of these conditions is not
adequate, the Flap Checks will not function properly.
If the surge hopper does not have an outlet to provide for proper venting due to a rotary airlock or other obstruction being located above it, or if it is impossible to tie into a dust control system, special arrangements must be made. One alternative is a Check Vent filter. The Check Vent is a pulse jet cartridge filter that is attached to the surge hopper and allows the air to be vented through the filter and expelled to the atmosphere. Any product that is vented is discharged back into the product air stream. A fan may or may not be required on the Check Vent filter.
Timing sequences will vary depending on the conveying characteristics of the material being transferred as well as the system configuration and capabilities. A typical timing sequence is 2 seconds to fill the Top Chamber and 2 seconds to empty the Top Chamber. Therefore you would be putting product into the line 15 times per minute. Some materials, like sand, may only take .4 second to fill the chamber, but it may take 3 seconds or more to empty it. Light materials may take a longer period of time to fill the chamber, but can be emptied within a second.
The clear Lexan panels are left on the valve if the product being conveyed is less than 200 degrees F. This unique feature allows operators to actually see the material going through the valve. This is invaluable when setting the timing sequences, trouble-shooting and performing maintenance on the unit. Although it would be expected that most abrasive materials would make the Lexan go opaque in a short period of time, the reality is that the velocities within the chambers are relatively low and the panels remain functional for a long period of time.
The main wear points on a Check-veyor are the Check Valve Assemblies (referred to as chutes) and the Flap Checks. The chutes can be carbon steel or chrome plated if the material is moderately abrasive. For more abrasive products, the chutes and seal face are lined with ceramic, giving the Check-veyor far superior abrasion resistant qualities than alternative airlocks. The Flap Checks are made with a flexible rubber material that allows the gate to hinge, with a highly abrasive resistant urethane type material called Kryptane being used on the sealing area. For temperatures over 200 degrees F, a belting material that is rated to 800 degrees F is utilized.
The Check-veyor can be sized for virtually any rate, the limiting factor is the system air mover. The volume of air available relative to the size of the Check-veyor valve is crucial for ensuring that the chambers can be emptied in a sufficient period of time. The valve can handle pressures up to 45 PSI, allowing us to do low velocity conveying in some cases or to convey over long distances.
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