Page:NTSB - Railroad Accident Report - Derailment on May 25, 1989.djvu/41

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color and continue to flash until acknowledged by the dispatcher. Testimony further indicated that if more than one condition occurs on the same page [screen], the word "alarm" and the audible alarm are terminated by one stroke on the computer keyboard.

The dispatcher testified that he noticed on his terminal screen flashing lights indicating that the pumps were shutting down and that he had a "low suction pressure" color alarm (blue). He did not notice the "low discharge pressure" color alarm (blue) on the same page. The dispatcher stated that he believed the pumps were shut down as a result of a low liquid level in the storage tank from which he was pumping. He was aware that a similar situation had been experienced by the dispatcher whom he relieved, and the pumps were eventually restarted. According to the dispatcher, the normal procedure for the condition of a low liquid level in a storage tank is to restart the pumps after the suction pressure again returns to normal. According to the dispatcher, normal suction pressure is between 26 and 50 psig. The suction pressure rose to 37.1429 psig, and at 8:06:02, the dispatcher commanded the restart of the 100-hp booster pump. At 8:06:11, the command was acknowledged by the computer. At 8:06:22, the computer reported the status of the booster pump[1] as "off."

At 8:06:53, the dispatcher again commanded the computer to start the booster pump, and at 8:06:57, the command was acknowledged. Operating parameters were automatically checked and found satisfactory, and the system attempted to restart mainline pumps Nos. 2 and 3. At 8:07:09, the computer acknowledged the command. At 8:07:19, another low suction pressure (17.2932 psig) alarm was given to the dispatcher who knowledged the alarm, and at 8:07:22, mainline pump No. 2 registered status "off," as did mainline pump No. 3 at 8:07:23. Also, at 8:07:23, the suction pressure was 46.1654 psig and at 8:07:55, the booster pump reported status "off."

At 8:08:10, the dispatcher acknowledged the shutdown alarms and again commanded the start of the booster pump. At 8:08:18, the booster pump acknowledged the command and at 8:08:19, pump No. 3 acknowledged the command. At 8:08:20, a low suction pressure (20.9023 psig) alarm was provided to the dispatcher. Pump No. 3 reported status "off" at 8:08:32, at which time suction pressure was recorded as 90.9774. At 8:09:15, the booster pump reported status "off." At 8:09:18, the shutdown was acknowledged by the dispatcher. The dispatcher stated that because he was not successful in restarting the pumps, he left his station to request assistance from another dispatcher who was on duty as a supervisor at the time and located down a hallway from the dispatch center. The supervisor acknowledged the request.

While returning to his dispatch area, the dispatcher encountered the senior systems specialist and asked him if he knew of any reason why the pumps would not come back on. The dispatcher stated that the systems specialist advised him to "pinch down" on the station control valve to bring

  1. A small capacity pump activated first to bring the pressure up slowly to prevent surging when the mainline pumps are activated.