3.5.12 CETP Instructor PowerPoint Template

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In order to use compressor to unload transports
and recover the vapor left in the cargo tank, it
is important to understand the process of
reducing vapor pressure.

• In this module you will identify
• U.S. DOT regulations pertaining to unloading
  operations and attendance requirements
• Reasons for reducing cargo tank pressure
• Procedures for recovering propane vapor using the
  bulk plant compressor

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DOT Regulations Pertaining to Unloading
Operations
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DOT Regulations Pertaining to Unloading
Operations

• The qualified person attending the unloading
  operation must remain within 25 feet of the cargo
  tank when the internal self-closing stop valve is
  open.
• The qualified person attending the unloading
  operation must have an unobstructed view of the
  cargo tank and delivery hose to the maximum
  extent practicable, except during short periods
  when it is necessary to activate controls or
  monitor the receiving container.
• When unloading the transport cargo tank using the
  plant compressor, the vehicle engine must not be
  running during the unloading operation.

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DOT Regulations Pertaining to Unloading
Operations

• The cargo tank must be equipped with a passive
  emergency discharge control system no later than
  the cargo tanks first pressure test scheduled
  after July 1, 2001. After that date it must have
  a means to automatically shut off the flow of
  product without the need for human intervention
  within 20 seconds of an unintentional release
  caused by a complete separation of a liquid
  delivery hose (passive shut-down capability).

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Reasons for Reducing Cargo Tank Pressure
Figure 1. Vapor Left in a Railroad Tank Car or
Transport Cargo Tank Expressed in Gallons of
Liquid LP-Gas
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Reasons for Reducing Cargo Tank Pressure
Figure 2. Propane Evacuation Time for a 33,000
Water Gallon Tank Car
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Reasons for Reducing Cargo Tank Pressure
It is not economical, however, to operate the
compressor for the time required to recover the
maximum possible amount of propane. To do so
requires expense of unloading attendant time,
electricity, and wear and tear on the compressor.
More than half of economically recoverable vapor
is removed in the first hour of compressor
operation. For that reason, many common carriers
and propane marketers who operate company-owned
transports, limit the vapor recovery time.
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Vapor Recovery Procedures
Plant vapor compressors are used in unloading
operations for the following reasons

• It saves time and eliminates the hazards
  associated with using the transport unloading
  pump.
• It allows for recovery of some of the propane
  that remains in cargo tanks after the liquid has
  been unloaded.
• It prepares the cargo tank for inspections,
  maintenance, or repairs.

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Vapor Recovery Procedures
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Vapor Recovery Procedures
Figure 3. Typical Plant Compressor
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Vapor Recovery Procedures
Figure 4. 4-Way Valve Vapor FlowPosition One
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Vapor Recovery Procedures
Figure 5. Compressor and Bulk Plant Connections
and Valves
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Vapor Recovery Procedures
Figures 6 7. 4-Way Valve Piping Valve
Positions
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Vapor Recovery Procedures
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Vapor Recovery Procedures
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Vapor Recovery Procedures
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Vapor Recovery Procedures
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Time to See If You Got the Key Points of This
Module

• Complete the Review on page 9 10.
• See if you are ready for the Certification Exam
  by checking off the performance criteria on page
  11 12.