Zenith® Pumps and The Extrusion Process
| | | ZENITH |
| ZENITH | ELECTRIC | PEP-II |
| HEAT PLATE | PUMP |
| ADDITIVE |
| |
| INJECTION | | |
| SYSTEM | | |
| | EXTRUDER | |
CHANGER
P T P
INLETPUMP DISCHARGE
PRESSURE TEMPERATURE PRESSURE
Zenith Pumps can handle all your extrusion pumping applications including additive injection for on-line compounding of tackifiers, colorants, stabilizers, etc.
Design
The PEP-II pump is constructed of two gears rotating in mesh within a closely fit- ted housing that is comprised of three plates. The center, or gear plate, fits closely around the outside diameter of the metering gears and bearings. The front and rear, or cover plates, sandwich the center plate and restrict axial movement of the gears and bearings. In capacities of 5 cc/rev and larger, the driving gear is manufactured integral with the drive shaft, and the driven gear is machined integral with its shaft. In capacities of 3.0 cc/rev and below, the gears are keyed to their respective shafts. In all capacities the shafts are supported by “D” shaped bearings which fit into the center plate. In capacities of 40 cc/rev and above, these bearings are located by two screws which pass through the cover plates. In capacities of 20 cc/rev and below, the bearings are keyed to each other for accurate location.
Each cover plate is secured to the center plate by 10 screws (6 screws for below 5 cc/rev). Each side of the center plate has a circular port in the center of a bolt circle for the mounting of adapter flanges that fit the pump to your equiment. Threaded holes are provided on the top and bottom of the center plate for the mounting of heat plates and for the mounting of the pump to its stand. Thermocouple wells (1/8-27 NPT) are located on the body of the pump.
A Zenith Rheoseal assembly secured to each cover plate (front cover plate only on 3.0 cc/rev and below) prevents leakage
around the shaft, using both dynamic and static types of sealing mechanisms. A Rheoseal consists of a helical groove on the inner diameter, a cooling jacket and a static, backup seal counter bore and gland. These spiral grooves allow the Rheoseal to act as a screw-type pump. As the fluid attempts to leave the gear pump, the shaft's rotary motion forces the fluid into the grooves. This creates a pres- sure greater than the pressure forcing polymer out of the pump, thus returning the polymer back towards the pump. Since the rotary motion is required of the shaft, two other static types of seals are employed on the Rheoseal—a spring energized lip-seal or a packing seal secured by the gland. Also a flushing cooling jacket surrounds a portion of the grooved seal. Use of the cooling jacket may be required for effective sealing if the viscosity is below 1,000 poise at process conditions. If used, water passing through the housing cools the polymer, increasing the effectiveness of the seal's pumping action. A thermocouple well is provided in the seal housing to allow for measuring the temperature close to the region where sealing actually occurs.
A complete line of accessories is available and includes heating plates (electric, oil and steam), adapter flanges, mounting blocks and pump drive systems complete with power package controls and process controls. Please contact Zenith or your local Zenith representative for further information.
