Reading Actual P&ID with Detailed Explanation

​Below is an actual example of P & ID for Heat Exchanger, we explained in detailed the function and used of each Instrument Bubble.

Heat Exchanger is a process unit in which steam is used to heat up a liquid material. The material, called feed stock, is pumped at a specific flow rate with pump P-101 into the pipes passing through the heat exhanger chamber (called the tube) where heat is transferred from steam to the material in the pipe. It is usually desired to regulate the temperature of the outlet flow irrespective of the change in the demand (flow rate) of the feed stock or change in the inlet temperature of the feed stock. The regulation of the outlet temperature is achieved by automatic control of the steam flow rate to the heat exhanger (E-101). The P&ID diagram utilizes certain stand symbols to represent the process units, the instrumentation, and the process flow.  

Signals on the P&ID:
Two kinds of signals are represented on the P&ID:
1. Electric Signals - represented by the dashed lines with red color on the P&ID.
2. Pneumatic Signals - represented by solid slanted lines with double strip across.

Detailed Explanation of each Instrument Bubbles:

Date Published: March 23, 2019
Source: Joel Hernandez - E & I Engineer - Qatar