Instrumentation. Test 3 – Online Maritime Tests

What is the difference between a PRESSURE SWITCH and a PRESSURE TRANSMITTER, if any?

The pressure switch gives out a digital signal dependent on pressure and temperatur.The pressure transmitter converts a pressure signal to a digital signal.
The pressure switch gives out an analogue signal depending on the switch setting.The pressure transmitter gives out a binary signal depending on the pressure.
The pressure switch has contact(s) that will change between open and closed position.The pressure transmitter converts a pressure signal into an electric signal.
There is no difference.

In connection with exhausts gas measurement with a thermocouple we are normally using an amplifier which gives a mA-signal out. Why is this done?

This depends on the length of the compensation-cable.
The signal out from a thermocouple is mV,and can not be transferred over any longer distance without loss of voltage, giving a very bad accuracy.
The signal out from the thermocouple is also mA, but have to be amplified in order to give a good signal to the alarm system.
To stabilize the signal.

What is the meaning of instrument calibration

Comparing two instruments of the same type
Adjusting size to fit process connection
Turning gauge too an easy reading position
Comparing input and output values against a documented standard

What is a typical problem when it is something wrong with the span of an instrument

Zero-point and 100% are correct, but not 50%
Zero-point is accurate, but 100% input is not giving 100% output
100% output is accurate, but Zero-point is wrong
Linearity problems

In installations of INTRINSICALLY SAFE equipment it is required that all equipment should be separated from non-intrinsically safe equipment, and to be of a special colour. What colour is that?

Green/yellow
Blue
Orange
Red

What is the meaning of the term

Type of standard output signal according to ISO
The maximum output signal when you have a minimum process value
The difference between maximum and minimum measurement that gives a standard output signal
The length between the connecting flanges

Review Answers