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Gas Compression / Vapor Recovery


  • Remote, stand-alone, vapor recovery compressors would occasionally shut down without notice, upsetting tank vapor pressures and creating a small potential for atmospheric release.
  • Capillary-style temperature switches were hard to adjust and maintain properly. The actual temperature shutdown setpoints would drift over time.
  • Two large gas compressors needed to run all the time to draw down the field gas pressure.
  • The PLCs controlling the main gas compressors could only be modified while off-line, necessitating a compressor shutdown for any setpoint change.
  • Two dozen safety switches needed to be tested and adjusted quarterly, reducing compressor uptime.


  • Installed (6) PLCs: four new PLCs and two upgrades.
  • Installed (6) HMIs: four new HMIs and two upgrades.
  • Installed backup vapor recovery compressors at (3) tank farms.
  • Automated those compressors so they would operate in a lead/lag fashion and notify operators of any abnormal conditions.
  • Installed RTDs on the compressors' discharge and collected that data into the PLC for alarming, trending and shutdown.
  • Installed a portable, VSD-driven gas compressor which could be used throughout the field, as needed, to reduce demand on the main compressors, allowing one to be shut down and used as a backup.
  • Networked the field compressors to the existing alarm notification system so operators would know the condition of their compressors at all times.
  • Replaced many switches with transmitters, reducing the time required for testing/calibration and increasing compressor uptime.
  • Provided detailed electrical drawings including:
    • PLC drawings
    • Motor control drawings


  • Increased product quality.
  • More productive employees.
  • More reliable equipment.
  • Better able to document environmental compliance.


Client: Pacific Coast Energy Company (PCEC)
Location: Orcutt, CA

  • (2) Allen Bradley - CompactLogix L35E
  • (3) Allen Bradley - MicroLogix 1400
  • (1) Allen Bradley - MicroLogix 1200
  • 179 discrete, 29 analog
  • (5) Allen Bradley - PanelView Plus 6, 10" color touchscreen panels
  • (1) Allen Bradley - PanelView Component, 6" color touchscreen panel
  • 250 tagnames
Remote Alarming:
  • Specter Instruments - Win-911 Enterprise (existing)
Data Historian:
  • Microsoft SQL Server (existing)
Other Components Integrated through SCADA:
  • Allen Bradley - PowerFlex 70 variable speed drive
  • Honeywell - TruLine chart recorders - DR4500
Networking, Protocols, and Drivers:
  • TCP/IP
  • RSLinx Enterprise
  • DH+
  • EIA-568A
  • RS-232