Intek 400 User Manual

Page 14

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Figure 4. Time Response Selection Jumper Location

TABLE II. Alarm2 Output Configuration (units with S2 option)

S1 Position



Relay2 State


Flow Rate

Liquid Level





Above set point






Below set point


The response time of the Model 400 can be changed between two settings: “Slow” and “Fast.” This
change is made by moving the jumper shunt at JP7 (see Figure 4). The unit will usually come from the
factory set in the “Slow” position. Notice that in the “Slow” position, the response is sluggish but noise-
free. The fast response position will cause any alarming to be accelerated, however, it will allow flow
noise to be present in the instrument’s output signal.

In general, when the output signal is being monitored, the “Slow” position is best. When the unit is used
strictly as a flow switch, it may be useful to use the “Fast” setting for gas flow or level monitoring
systems, and the “Slow” position for high velocity liquid flow systems. Figure 5 shows typical response
differences between the two settings.


The Model 400 instrument is compensated for a wide range of both ambient and flowing media
temperatures. However, abrupt changes in the temperature of the flowing material can cause the
instrument output to deviate from the true representation of flow rate, which in turn could lead to an
inappropriate tripping of the relay or a delay in reading a loss of flow. A proper reading is obtained only
when the transducer is in thermal equilibrium with the material. Typically, a 20°F abrupt change in
temperature may require 40 seconds to stabilize. Temperature ramps should be kept below 1°C/minute.

In general, the heater used in the transducer does not develop enough power to cause damage to the
system in the absence of
flow. This includes those
used in liquids even if the
line becomes empty and is
filled with air. Rheotherm
instruments have additional
circuitry which prevents
overheating in the event of
the loss of flow. This
thoroughly protects the
instrument from damaging
itself. Although it is not
required, it is recommended
that the instrument power be
shut off when the instrument
is not in use. Any special
cases concerning unique
requirements may be
discussed in SECTION 6,