IO-2
Optional Parts and Equipment
2. Functional description of
optional features
Four optional features may be purchased with Series 2300 applicators:
parent machine interlock, digital readout, low temperature setback, and
low level indication. Each of these four is described in the following
paragraphs.
Parent machine interlock (PM/J
A Parent Machine Interlock performs two basic functions: it indicates
when the adhesive in the tank has reached application temperature (an
indicator light turns off) and, once this temperature is reached, it
energizes a contact which may be used to operate a normally open or a
normally closed switch on a parent machine. You can, for example, use
PMI to ensure that a packaging line does not run unless the adhesive is
fully melted.
Although an operator can easily tell when the tank walls have reached
application temperature-the yellow LED of the tank circuit begins to
flash-it typically takes 15-20 minutes longer, depending upon the
adhesive used, for all of the adhesive to reach the same temperature.
The PMI is essentially a time delay which takes this difference into
account. It begins timing when the tank control channel reaches the
set, or application, temperature, that is, when it begins proportioning
and the tank’s yellow LED is flashing. It completes its time-delay cycle
when the number of minutes for which it is set (determined from past
experience with the adhesive used) have passed. The delay cycle is
adjustable between 12 and 22 minutes. Once the set time period has
elapsed, the PMI “wait” light on the indicator panel (see Figure 2.4)
turns off and an output relay is actuated, allowing interface with either
normally closed or normally open contacts.
After the initial start-up sequence, the PMI operates somewhat
differently. During normal operations the adhesive may occasionally
drop below the application temperature for several reasons, the most
common one being the refilling of the tank with fresh adhesive. If
enough cold adhesive is added that the temperature of the tank wall
drops more than about 3’F (1.5’C) below application temperature (also
called the setpoint temperature), the tank heating circuit will stop
proportioning and will apply heat steadily until the set temperature is
reached again. In this situation the PMI may be set by a switch on the
interlock board to do one of two things: either to ignore the drop of the
tank below application temperature or to activate the “wait” light and
deenergize the output relay. In the first situation the applicator will
operate as it would without a PMI. In the second situation the PMI will
perform as follows. If the tank temperature falls below the application
temperature for only a short period of time (less than about six
minutes), the output relay will be deenergized only until the tank
heating circuit begins to proportion again. But if the tank is out of the
proportioning range for longer than six minutes, the time delay will be
activated and the wait period will include the time delay, allowing the
adhesive in the tank to reach the application temperature again.
PM 106 701A
41-2300SP - Issued 1,94
0 Nordson Corporation 1994
All Rights Reserved
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