Fluid-components-international FLT93 Nuclear Manuel d'utilisateur télécharger pdf (Page 28)

OPERATION FLT

Series FlexSwitch

28 Fluid Components International LLC

Note: The alarm can be set for a speciﬁ c ﬂ ow rate. Follow the Air/Gas Flow Application procedure up to step 7 except establish the

speciﬁ c ﬂ ow rate rather than the normal ﬂ ow. The output signal will be the set point value. Determine whether the alarm

should actuate with decreasing or increasing ﬂ ow and skip to the appropriate step 4 in Detecting Decreasing Flow or Detect-

ing Increasing Flow, respectfully. Enter the speciﬁ c ﬂ ow rate value as the set point. Then follow the Continue With the Air /

Gas Flow Procedure steps.

The relay logic default conﬁ guration is set for the relay coil to be de-energized when the ﬂ ow signal voltage is greater than

the set point value. (i.e., Assume that the normal process ﬂ ow condition has been established. In this state, the relay coil

will be energized if the alarm has been set for low-ﬂ ow detection and de-energized if the alarm has been set for high ﬂ ow

detection.) A recommendation is to have the relay coils energized when the process condition is normal. This will enable the

alarm to close or open the contacts in case of a power failure.

Adjustment by Observation

Note: The control circuit has two mutually exclusive alarms; they are identiﬁ ed as Alarm No. 1 and Alarm No. 2 and each has a set

point adjustment potentiometer and LED indicator. Each alarm can be setup for one of three applications: ﬂ ow, level/inter-

face, or temperature. The following application speciﬁ c adjustment procedures are generic and can be used for setting either

or both alarms. The mode switch must be in the RUN position. Use Figure 3-2 to help locate the adjustment potentiometers

and LEDs.

Flow Applications

1. Ensure that the instrument has been properly installed in the pipeline. Fill the pipeline so the sensing element is surrounded by the

process medium.

2. Apply power to the instrument and allow ﬁ fteen minutes for the sensing element to become active and stabilize.

3. Flow the pipeline at the normal or expected rate. Remove the enclosure cover to allow access to the control circuit to make adjustments.

Detecting Decreasing Flow (low ﬂ ow alarm)

If the status LED is off, turn the set point adjustment potentiometer clockwise until the LED turns on. With the LED on, slowly turn the po-

tentiometer counterclockwise one turn past the point at which the LED just turns off. The potentiometer may have up to one-quarter turn of

hysteresis, therefore, if the mark is overshot, the procedure should be repeated.

Detecting Increasing Flow (high ﬂ ow alarm)

If the status LED is on, turn the set point adjustment potentiometer counterclockwise until the LED turns off. With the LED off, slowly turn the

potentiometer clockwise one-half turn past the point at which the LED just turns on. The potentiometer may have up to one-quarter turn of

hysteresis, therefore, if the mark is overshot, the procedure should be repeated.

Signal Output for Flow Applications

The output signal at connector P1 varies inversely with ﬂ ow rate. The output signal level is also relative to the type of process media, see

Figure 3-3.

Level Applications

1. Ensure that the instrument has been properly installed in the vessel.

2. Apply power to the instrument and allow ﬁ fteen minutes for the sensing element to become active and stabilize.

3. Remove the enclosure cover to allow access to the control circuit to make adjustments.

Detecting Dry Condition (adjustment with sensing element wet)

Verify that the sensing element is wet. If the status LED is off, turn the set point adjustment potentiometer clockwise until the LED turns on.

With the LED on, slowly turn the potentiometer counterclockwise one turn past the point at which the LED just turns off. The potentiometer

may have up to one-quarter turn of hystereses, therefore, if the mark is overshot, the procedure should be repeated.

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Fluid-components-international FLT93 Nuclear Manuel d'utilisateur Page 28

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