TUNE YOUR LOOP: Questions to keep you sharp.

Tune Your Loop is a series of posts consisting of questions from ISA Training Courses.

1. To compute capacitive reactance the following formula is used. Xc = 1/ 2Πfc.

(“c” is expressed in farad and “f” is expressed in hertz.) What is the capacitive

reactance if the frequency is 60 Hz and the capacitor size is 5 micro farad.

[ordered_list style=”lower-alpha”]

- .019Ω
- 5.31Ω
- 531Ω
- 5310Ω[/ordered_list]

2. The temperature range of a transmitter is 100 -300°F. The output signal range is

3-15PSI. What would be the expected output signal for an input temperature of

175°F.

[ordered_list style=”lower-alpha”]

- 4.5PSI
- 6PSI
- 7.5PSI
- 13.5PSI[/ordered_list]

3. If the flow rate remains constant in a fluid line and the pipe diameter in one

section is 10 inch with a velocity of 2 feet per second what will be velocity

through the pipe be when the fluid passes through the pipe when it is reduced to

4 inches? (The formula is Flow rate = velocity times area of the pipe. [Q=VA]The

formula for area of the pipe is ΠR2.)

[ordered_list style=”lower-alpha”]

- 6.25 ft/sec
- 12.5 ft/sec
- 5.0 ft/sec
- 1.25 ft/sec[/ordered_list]

4. During calibration, the maximum error was 2.5 units over a span of 50 units.

What is the percent of span error?

[ordered_list style=”lower-alpha”]

- 20%
- 5%
- .5%
- 2.5%[/ordered_list]

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