as previously discussed. Note that all data given within this section regarding level management was acquired using an Extru-Tech Model 16X72 DCC, running at rated capacities. With this setup, a retention time of 20 to 35 seconds is expected at a dead-stop weight of 50 to 60 lbs. Dead-stop weight is the weight captured within the preconditioner after the system is stopped abruptly upon reaching a steady state of operation.

Applications suited to this configuration are processes requiring dynamic inline mixing, with minimal water or thermal absorption.

Figure 12 represents an industry-typical configuration. As feed enters the preconditioner inlet (on the left), the forward pitch paddles move the product away from the inlet into the center of the preconditioner. The middle

section, set to neutral, provides the mixing and an environment for thermal and water absorption.

The end section, marked as reverse pitch, provides retention time control by adding a negative conveying component to the system. Increase the length of this section, and the retention time increases. Conversely, decreasing the length of this section decreases the retention time. With a typical setup of each section, the average process can expect retention times of 35 to 65 seconds, with dead-stop weights of 60 to 95 lbs.

Figure 13 shows a new configuration recently developed, tested and proven by ETI. With this new configuration, ETI learned there were advantages of reducing the forward conveyance from the preconditioner

Figure 12 This illustration represents an industry-typical configuration. As feed enters the preconditioner inlet, left, the forward pitch paddles move the product away from the inlet into the center of the preconditioner.

Figure 13 This illustration shows a new configuration developed by Extru-Tech, Inc. Here, ETI learned there were advantages of reducing the forward conveyance from the preconditioner inlet.

September 2007 Extru-Technician 9