Lubrication Alarms

DuPont s Sabine River Works experience shows that it is crucial to segregate the more critical interlocks from the others. A few well-understood, respected interlocks are said to be better than an overwhelming number of interlocks with the critical ones scattered amongst the others. DuPont s system allows a range of required authorizations. At DuPont, a supervisor may bypass less critical interlocks such as lubrication alarms for up to 24 hours for testing and repairs, but some of the more critical alarms may not be bypassed by anyone. 

These are instrument system loops that are necessary to avoid a failure which could result in nonreportable environmental releases, equipment or production losses, or reduced economic life, plus all other systems and alarms that assist operations that require prooftesting. These alarms and shutdown systems include refrigeration units that have less impact or safety or environmental issues than the Class 2 units, important pump shutdown alarms, low pressure utility alarms (well water, cooling tower water, natural gas, instrument air, nitrogen), and numerous low-pressure lubrication alarms. 

Improved sensors allow computer monitoring of the system for safety and protection of the equipment from damage. Sensors include lubrication-flow monitors and alarms, bearing-temperature sensors, belt scales, rotation sensors, and proximity sensors to detect ore level under the crusher. The latter prevent jamming of the output with too high an ore level, and protect the conveyor from impact of lumps with too low an ore level. Motion detectors assure that the conveyor is moving. Control applied to crusher systems including conveyors can facilitate use of mobile crushers in quarries and mines, since these can be controlled remotely by computer with reduced labor. 

A typical lubrication oil system is shown in Figure 15-1. Oil is stored in a reservoir to feed the pumps and is then cooled, filtered, distributed to the end users, and returned to the reservoir. The reservoir can be heated for startup purposes and is provided with local temperature indication, a high-tempera-ture alarm and high/low level alarm in the control room, a sight glass, and a controlled dry nitrogen purge blanket to minimize moisture intake. 

In a batch reaction plant, an exothermic reaction was cooled by water circulating in a jacket. The circulating pump failed and the reactor went out of control causing a violent explosion. A low flow alarm was present but was inoperable. A critical pump bearing had not been lubricated during maintenance, and the collapse of the bearing had led to the pump failure. 

Cooling and Lubrication Failures. All hydrogen gas compressor units shall be equipped with shutdown or alarm devices to activate in the event of inadequate cooling or lubrication of the units. 

Normal Consequence—Class 3. All other containment equipment or instrumentation serving the operation whose failure could result in minor environmental releases, property or production losses, or injury to personnel or reduced economic life. It may include less critical refrigeration systems, turbine overspeed trips, lubrication system alarms and similar important, but not crucial items. 

Lubricant condition monitoring is best accomplished by the analysis of numerical data that are associated with the various fluid failure modes [2]. Numerical data can be analysed by statistical methods to determine the relationship between the various test parameters and their respective fluid and machinery failure modes. In addition, the statistical analysis can be used to determine potential data interference sources, the various alarm limits for each parameter and other criteria to be used in the daily evaluation of used oil. Note that it is important to determine all of the causes for variability in parametric data, just as it is necessary to separate changes due to interfering causes from changes with its associated relevant failure modes. 

The silicon readings by themselves were not cause for alarm, but they were when combined with RFS data for iron. The RFS trend for iron jumped enough for the laboratory to issue a severe alarm after the January 9, 2003 sample. The maintenance response was to feed and bleed, i.e., drain some lubricant and top it off. The next two RFS analyses showed a corresponding reduction in the iron analyses. However, the May 22,2003 sample indicated that... 

For oil-lubricated compressors, the employer shall use a high-temperature or carbon monoxide alarm, or both, to monitor carbon monoxide levels. If only high-temperature alarms are used, the air supply shall be monitored at intervals sufficient to prevent carbon monoxide in the breathing air from exceeding 10 ppm. 

All the problems associated with chlorine compression apply to diaphragm compressors. They must be protected against combustion of metal parts in dry chlorine. Since the compressor head usually is carbon steel, this means a maximum temperature of about 120°C. There must be no contact between chlorine and a combustible lubricant. Double separation between the two, as was the case with reciprocating compressors, can prevent this contact. Two diaphragms with an inert intermediate fluid are standard. The oil can be a chlorinated fluorocarbon that does not react with chlorine. The space between diaphragms should have a leak detector that sounds an alarm and shuts down the compressor when either diaphragm fails. 

Lubricating oil is pumped from a reservoir to the compressor and then runs down from the machine to the tank. The tank should have level and temperature indication and a low-level alarm. The pumped oil is cooled and filtered before going to the compressors. Dual filters rated at about 10 p.m are used, and a standby pump is provided. The oil must be dry, and so its reservoir is frequently blanketed with nitrogen. Some of the alarms on the oil system will be supplemented by shutdown switches in case operator action fails to prevent further departure from the control point. 

Description— These devices provide air to the wearer through a small-diameter, high-pressure hose line from a source of uncontaminated air. The source is usually derived from a compressed airline with a valve in the hose to reduce the pressure. A filter must be included in the hose line (between the compressed airline and the respirator) to remove oil and water mists, oil vapors, and any particulate matter that may be present in the compressed air. Internally lubricated compressors require that precautions be taken against overheating, as the heated oil will break down and form carbon monoxide. Where the air supply for airline respirators is taken from the compressed airline, a carbon monoxide alarm must be installed in the air supply system. Completion of a prior-to-operation preventive maintenance check on the carbon monoxide alarm system is critical. 

For an oil lubricated air compressor, carbon monoxide can be produced where oil enters into the compression chamber and is partially combusted. Carbon monoxide can also enter the air intake for the compressor if the intake is not properly located. This type of compressor must have either a carbon monoxide alarm, high temperature alarm, or both. If only a high temperature alarm is used then the breathing air must be tested for the presence of carbon monoxide at intervals sufficient to ensure that carbon monoxide levels do not exceed 10 ppm. 

Is it required for an employer to monitor for the presence of carbon monoxide if an oil-lubricated compressor equipped with a high temperature alarm or automatic shutoff device is being used ... 

Flow measurement is employed on the oil lubrication lines, but is usually of the rotameter, or variable orifice type. This means that they are used for indication only, and are not readily coupled into the control system, unless simply as alarm features. 

Guards can be removed in order to perform repairs or to lubricate machines. Interlocks on trash compactors and other machines are intended to stop a machine when a guard or door has been opened. Speed governors and back up alarms on lift trucks are provided for the protection of employees and pedestrians. An example that must always be a high priority to prevent is removing a lockout and tagout device from an electrical box or machine, which can result in serious injury or death. 

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