Safety homework

A-P-T Research, Inc.

E-04-027

Barney
in the
Basement

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E-04-027

A Brief PHA Case Study…

• An underground vault contains a distribution system for a dense inert gas (IG). The vault is equipped with a forced ventilation system to provide seven air changes per hour; and an electrically powered sump pump with a float switch control. The ventilating blower is started from a switch at grade level, near the entry point. The sump pump starts automatically. The vault also contains a pressurized, 4-inch diesel fuel line and a 4-inch water line. Both pass through, near the ceiling, with no exposed fittings. The confined space is approx. 28 ft. x 18 ft. x 18 ft. A stairway provides ingress/egress.

• No history of system leakage is available for the IG system, but there are many connections and threaded fittings. The diesel fuel and water lines were installed within the past 6 months. The sump pump removes surface water which occasionally infiltrates the space. Its operation has been satisfactory. An oxygen deficiency detection and alarm system is permanently installed, has battery backup, and is maintained and tested regularly. It has been found inoperative on several occasions over a 10-year period. Recent improvements are thought to have corrected its faults.

• Work crews frequently enter the confined space (install and remove IG bottles, etc.). Full-time occupancy is a reasonable assumption.

• No smoking or welding are allowed in the confined space.

• Prepare a PHA for all identifiable hazards to any possible target in or near this confined space. Assume an exposure interval of 30 years.

System Safety Analysis Problem 93-11

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E-04-027

System Safety Analysis Problem 93-11

Underground Vault…

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E-04-027

Preliminary Hazard Analysis…

System Safety Analysis Problem 93-11

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E-04-027

Assignment

• Complete the PHA for Barney in the Basement.  Scan the completed document and upload 
• You are to ignore the "RISK CODE" column on the worksheet.
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