4
DESCRIPTION cont.
two variations of batch control. The first, and most common is the single valve
approach represented by the diagram below.
Single Valve Batch Control
Analog Signal In
Flowmeter
Valve
Flow
PGM
View
Edit
Enter
Start
Reset
Stop
PGM
BATCH
Durant
Relay 1
Out
Assume that a cosmetics manufacturer has just blended a 100,000 gallon vat of his
economy perfume, and that he wants to ship it to his customers in 55 gallon drums.
The operator enters 55 into the
batch final
preset by using the keys on the front
panel of the Eclipse batcher. When an empty drum is in place beneath the outlet
pipe, the operator presses the
start
key. This causes the batch final relay, (relay 1) to
turn ON, which in turn, opens the solenoid valve. With the valve open, perfume flows
from the vat to the drum. The flowmeter detects the flow and sends a signal to the
counter. The counter happily integrates this signal and counts up to 55. At this point,
the batcher realizes that the amount delivered to the drum is equal to the amount
entered by the operator in the batch final preset. The batch final relay turns OFF,
shutting the valve. When the operator has removed the full drum and placed another
empty drum under the outlet pipe, he again presses the start key and another batch
of 55 gallons will be delivered.
Once the batch delivery has been started, it will normally shut off automatically at the
batch final preset value. However, most users will want the ability to manually stop
the delivery as well. Assume that the operator had started his 55 gallon batch, and
then noticed that the drum had a hole in its side. The operator would then press the
front panel
stop
key, which would immediately turn the batch final relay OFF, shutting
the valve. Now the operator has a decision to make. Perhaps he can plug the hole
with a piece of chewing gum. In this case, he makes the repair and resumes delivery
of the batch from where he stopped by pressing the start key again. However, maybe
the operator determined that the hole could not be repaired. Then he would termi-
nate the batch by resetting the counter. The
resume
function, completing a batch
after it had been manually stopped, and the
terminate
function, ending a batch after
a manual stop, are necessary functions of a batch control.
