How to

How to Read Pressure Transmitter Hookup Drawings ?

Pressure transmitter hookup drawings are critical documents in instrumentation engineering. They provide detailed instructions for installing and configuring pressure transmitters within a system, ensuring accurate measurement and seamless integration with control system. This guide will walk you through the process of interpreting these drawings, offering in-depth explanations and practical tips for instrumentation project engineers and supervisors.

Understanding hookup drawings is crucial for several reasons:

  1. Ensures correct installation and configuration of pressure transmitters.
  2. Prevents errors that could lead to measurement inaccuracies or system failures.
  3. Facilitates effective communication between different teams (e.g., instrumentation, piping, electrical).
  4. Helps in troubleshooting and maintenance procedures.
  5. Ensures compliance with industry standards and regulations.
How to Read Pressure Transmitter Hookup Drawings 1
  • Situated in the drawing’s lower right corner.
  • Indicates the type of instrument, e.g., “Pressure Transmitter – Steam with Condensate Pot”.
  • Helps in quickly identifying the drawing’s purpose.
  • Found within the title block, e.g., “DWG.NO. STD-4-IHU-1000”.
  • Crucial for reference and document control, uniquely identifying the drawing within a set of documents.
  • Also located in the title block.
  • Revision Number indicates the version of the drawing (e.g., Rev 1, Rev 2).
  • Sheet Number identifies the drawing’s place within a set (e.g., “Sheet 47”).
  • Included in the title block.
  • Indicates the organization responsible for the drawing.
  • Useful for accountability and contact information.

Best Practice: Always ensure you’re working with the latest revision of the drawing.

How to Read Pressure Transmitter Hookup Drawings 2

Location: Often found near the bottom or side of the drawing Key Aspects: a) Installation Instructions:

  • Example: “Transmitter to be mounted on 2″ pipe mounting and shall be at accessible height”
  • Provides critical details not easily conveyed in the graphical portion 
  • Look for any unique specifications or warnings
  • May reference relevant standards or regulations from the company.

Best Practice: Read all notes carefully before proceeding with the interpretation or installation.

How to Read Pressure Transmitter Hookup Drawings 3
  • Look for an arrow on the drawing, indicating the direction of process media flow.
  • Use this to correctly orient the transmitter and associated components.
  • Correct orientation avoids installation mistakes that can cause problems with operation.
  • Inlet and Outlet: Identify which part of the system is upstream and downstream

Best Practice: Always orient your visual model of the system based on the flow direction.

How to Read Pressure Transmitter Hookup Drawings 4
  • Examine the drawing to locate and identify various symbols representing different components.
  • For information on what each sign means, see the legend on the diagram or inside the drawing.
  • Process Pipe (01): Represents the main pipe carrying the steam.
  • Condensate Pot (05): Collects condensate to protect the transmitter.
  • Isolation Valve (04): Allows for isolation of the transmitter for maintenance.
  • Pressure Transmitter (09): Measures the steam pressure.
  • Tubing and Fittings: Connect various components, ensuring a sealed path for steam and condensate.
  • Cable and Cable Gland (10, 11): Provide electrical connections for transmitting data from the transmitter to the control system.

Best Practice: Familiarize yourself with common instrumentation symbols used in your industry or company.

How to Read Pressure Transmitter Hookup Drawings 5
  • A comprehensive list of all necessary components is provided by the BOM, which is usually located at the side or bottom of the drawing.
  • Columns include item number (SR. NO), description, size, quantity, and scope.
  • Verify each component’s location and connection by comparing the BOM with the main drawing.
  • For example :
  • SR. NO 09: “Pressure Transmitter, 1/2″ NPT (M), Quantity: 1”.
  • Description: Indicates the type and size of the pressure transmitter.
  • Size: Specified according to the process and instrumentation requirements.
  • Quantity: Specifies the number of units required.

Best Practice: Cross-reference each item in the BOM with its corresponding symbol on the drawing.

How to Read Pressure Transmitter Hookup Drawings 6
  • Examine the lines in the drawing to understand how each component is connected.
  • Solid Lines: Represent piping or tubing that physically connects components.
  • Dashed Lines: Often indicate signal or electrical connections.
  • Use the symbols identified in Step 4 to follow the connections.
  • Ensure each symbol corresponds to the correct component in the BOM.
  • For example:
  • Signal Cable (11) connects to the transmitter, indicating control signals from the control system to the transmitter.
  • Ensure the cable gland (10) is used for a secure connection of the signal cable.

Best Practice: Trace each connection from start to finish to understand the complete flow path.

  • The drawing is divided into sections like “Piping Scope” and “Instrument Scope”, indicating the boundaries of work for different teams.
  • Example: The piping scope includes the installation of the condensate pot and associated piping, while the instrument scope covers signal cables and instrumentation.

Significance: Clarifies responsibilities for different teams or contractors

  • Pay attention to dimensional notes, such as the required height and mounting instructions for the transmitter.

Best Practice: Ensure all dimensional requirements are feasible in the actual installation environment.

  • provide detailed installation instructions that include orientation requirements for the transmitter, specific torque values for connections, and any necessary requirements for heat tracing or insulation. 
  • Additionally, include the calibration or testing procedures that should be followed after installation.

Best Practice: Create a checklist of all specific instructions to ensure nothing is overlooked during installation.

It is essential to ensure that all components meet the following criteria:

  • Pressure Ratings: Confirm that all components meet or exceed the system’s maximum pressure requirements.
  • Temperature Ratings: Verify that the materials are compatible with the process temperature range.
  • Material Specifications: Check that the materials used are suitable for the process fluid and the environmental conditions they will encounter.
  • Certifications or Standards: Ensure that all components possess the necessary certifications, such as explosion-proof or intrinsically safe ratings.
  • Refer to the callouts on the drawing that provide more information about each component.
  • For example:The condensate pot (05) is indicated with a specific callout showing its connection details and purpose in preventing water from reaching the transmitter.

Best Practice: Cross-reference these specifications with the actual components to ensure compliance.

  • The Process and Instrumentation Diagram (P&ID) provides a comprehensive overview of the process flow and instrumentation setup.
  • Includes all control loops, process equipment, piping, and instrumentation details.
  • Familiarize yourself with relevant industry standards (e.g., ASME, ANSI, IEC)
  • Ensure all installations adhere to these standards and any local regulations
  • Use manufacturer’s datasheets for detailed component specifications
  • Refer to general installation guidelines provided by the transmitter manufacturer
  • Always verify the actual field conditions against the drawing
  • Note any discrepancies and update the drawing if necessary
  • Discuss any concerns with the project engineer or designer
  • Ensure clear communication between piping, instrumentation, and electrical teams
  • Keep detailed records of any deviations from the drawing during installation
  • Document any field changes for future reference and drawing updates
How to Read Pressure Transmitter Hookup Drawings 7

Let apply our knowledge to analyze the below provided sample drawing of a pressure transmitter hookup for a steam system with a condensate pot.

  • Company:xxxxxxxxxxxxxxx
  • Title: Pressure Transmitter – Steam with Condensate Pot
  • Drawing Number: STD-4-IHU-1000
  • Sheet Number: 47

Significance: This drawing is a standard hookup (STD) for a specific pressure transmitter configuration used by particular industry only.

  • A diagonal arrow labeled “FLOW” indicates the direction of steam flow in the main process pipe.
  • The flow appears to be from the top-right to the bottom-left of the drawing.

Importance: This orientation is crucial for understanding the placement of the condensate pot and transmitter relative to the flow.

  • Represented by a thick horizontal line at the top of the drawing.
  • This is the main steam pipe from which the pressure measurement is taken.
  • Located below the process pipe, connected via a small pipe section.

Purpose: Collects condensate to protect the transmitter from direct contact with hot steam.

  • Three isolation valves are shown:
    1. On the connection from the process pipe to the condensate pot.
    2. On the line connecting the condensate pot to the transmitter.
    3. On a drain line at the bottom of the setup.

Purpose: Allow for isolation of different parts of the system for maintenance or replacement.

  • Located at the bottom-left of the drawing.
  • Shown mounted on a vertical pipe section.
  • Connected to the condensate pot via tubing and an isolation valve.
  • Thin lines connecting various components represent tubing.
  • Several fittings and connectors are shown, ensuring proper connections between components.
  • A cable gland is shown connected to the transmitter.
  • A dashed line represents the signal cable running from the transmitter.

The BOM at the bottom of the drawing provides detailed information about each component:

  1. Process Pipe (01): Size not specified, quantity 1, falls under piping scope.
  2. WS Socket (02): 1/2″ NPT (F), quantity 1, falls under piping scope.
  3. Barrel Nipple (03): 1/2″ NPT (M), quantity 1, falls under instrumentation scope.
  4. Isolation Valve (04): 1/2″ NPT (F), quantity 3, falls under instrumentation scope.
  5. Condensate Pot (05): 1/2″ NPT (F), quantity 1, falls under piping scope.
  6. SS-304 Seamless Tube (06): 1/2″ O.D., quantity as required, falls under instrumentation scope.
  7. Compression Type Tube Connector (07): 1/2″ NPT (M) to 1/2″ O.D., quantity 8, falls under instrumentation scope.
  8. Blinding Plug (08): 1/2″ NPT (M), quantity 1, falls under instrumentation scope.
  9. Pressure Transmitter (09): 1/2″ NPT (M), quantity 1, falls under instrumentation scope.
  10. Cable Gland (10): 1/2″ NPT (M), quantity 3, falls under instrumentation scope.
  11. Cable (11): Size not specified, quantity as required, falls under instrumentation scope.
  12. Staunch (12): Not specified, quantity 1, falls under instrumentation scope.
  • A crucial note is provided at the bottom of the drawing: “NOTE: 1) TRANSMITTER TO BE MOUNTED ON 1/2″ PIPE AND SHALL BE AT ACCESSIBLE HEIGHT.”
  • This note emphasizes the importance of proper mounting and accessibility for maintenance and operation.

The BOM clearly divides the components into two scopes:

  1. Piping Scope: Includes the main process pipe, condensate pot, and associated fittings.
  2. Instrumentation Scope: Covers the transmitter, valves, tubing, and electrical components.

This division helps clarify responsibilities between different installation teams.

  • The transmitter is shown mounted vertically on a 1/2″ pipe.
  • While specific heights are not provided, the note emphasizes accessibility.
  • The condensate pot is positioned above the transmitter, allowing for proper drainage.
  • NPT (National Pipe Thread) connections are used throughout, with sizes specified in the BOM.
  • The drawing shows a mix of male (M) and female (F) connections, ensuring proper mating of components.
  • Multiple isolation valves allow for safe maintenance of the transmitter and condensate pot.
  • A drain valve at the bottom of the setup allows for system drainage when necessary.
  1. Accessibility: The note emphasizes mounting the transmitter at an accessible height, crucial for ease of maintenance and operation.
  2. Protection: The use of a condensate pot protects the transmitter from direct contact with hot steam, extending its life and ensuring accurate measurements.
  3. Flexibility: Multiple isolation valves provide flexibility in maintenance and troubleshooting.
  4. Clear Scope Division: The clear division between piping and instrumentation scopes helps in project planning and execution.

Click here for How to Read Control Valve Hookup Drawings?

Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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