Intek 200 - Manual (Page 15)

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SECTION 3 ! OPERATION
3.1 START UP
Typically, the instruments come from the factory set up for the flow range of interest to the customer.
Following installation all that is required is to switch on power and initiate flow in the measurable flow
rate range. Flow sensors that are not calibrated directly on the fluid to be measured are so indicated in
this manual (SECTION 6) and require an in-line field calibration.
When power is first turned on, the output reading or signal will indicate full scale. The alpha numeric
display will have the message of ‘*INTEK, INC.*’ on the top line and ‘(614)895-0301’ on the bottom.
After a few seconds the message will change to ‘s/n xxxxx-xx Cal x’ / ‘Software Ver: xxxxxx’. Again
after a few seconds the top display line will change to ‘initializing.’ The status output will be low (alarm
condition) and the flow output will be 100%. The flow value will be internally software monitored for
stability or a factory set time-out (10 sec. default) will occur before the display is set to the normal state
(Flow / Temperature will be the factory default). After ten to forty-five seconds (depending on flow
meter response) the reading will stabilize. The instrument time constant is generally between 4 to 12
seconds. Higher average flow rates will result in an observed faster response time for a given unit.
3.2 GENERAL INFORMATION
The Rheotherm 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. An accurate 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. To maintain optimum accuracy temperature ramps
should be kept below 1°C/minute.
Rheotherm instruments are calibrated for a particular fluid, either at the factory or in the field. If the
fluid changes properties, the calibration changes. Therefore, once calibrated, do not allow fluid
properties such as density and viscosity to change (other than the intrinsic changes which occur with
temperature variation). If the fluid is changed, a recalibration may be attempted following the procedure
in SECTION 3.4.3. If this procedure does not provide a good calibration for the range of interest on
the new fluid, contact the factory.
3.3 OUTPUT SIGNALS
Standard features for all Model 200 instruments include one 2 x 20 alpha numeric LED backlit display,
two 4-20 mA or 0-10Vdc analog outputs, one 0-15Vdc digital pulse flow output, two 0-15Vdc digital
flow/temperature alarm outputs, one 0-15V digital status port, and one serial communication port. Both
flow and temperature process variables are linear, temperature compensated values. Each output signal
is scaled such that 4 mA (0Vdc for voltage output) represents 0% of the rated full scale value and 20 mA
(10Vdc) represents 100% of the rated full scale value. The factory set full scale values and definitions
of process variables are listed in Table II.