OIT Blueprint Reading and Technical Drawing 3

Question 1

What does the symbol '⌀' (circle with a diagonal line through it) represent in technical drawings?

Accepted Answer

The diameter of a circular feature

Answer

The '⌀' symbol is the diameter symbol, indicating that the following numerical value specifies the diameter of a circular or cylindrical feature.

Question 2

What is the purpose of a revision block (revision history) on a technical blueprint?

Accepted Answer

To record changes made to the drawing after original release, including date and reason

Answer

The revision block records all changes made to a drawing after its original issue, including revision letter/number, description of change, date, and authorizing signature.

Question 3

What do phantom lines (long dash, two short dashes pattern) represent in technical drawings?

Accepted Answer

Alternate positions of moving parts, adjacent parts, or repetitive features

Answer

Phantom lines show alternate positions of moving parts, the outline of adjacent parts for reference, or indicate repetitive detail to avoid drawing the same feature multiple times.

Question 4

In process engineering blueprints, what does the abbreviation 'P&ID' stand for?

Accepted Answer

Piping and Instrumentation Diagram

Answer

A P&ID (Piping and Instrumentation Diagram) is a detailed schematic showing the piping, vessels, equipment, instrumentation, and control devices within a process system.

Question 5

What is the purpose of a break line (short wavy or zigzag line) in a technical drawing?

Accepted Answer

To show that a long object has been shortened in the drawing while maintaining its true length dimension

Answer

Break lines indicate that a portion of the object has been omitted from the drawing to save space, but the full dimension is still noted accurately.

(OIT) Ontario Industrial Trades Certification Practice Test

(OIT) Ontario Industrial Trades Certification Practice Test

OIT Blueprint Reading and Technical Drawing 3