System controls and monitoring

The controls and instrumentation discussed in this section include sensors, control switches and position indicators for components and valves, as well as other 

The following factors should be taken into consideration  

In general, the controls and instrumentation of the waste management systems are not required to be redundant. However, if the controls and instrumentation are for systems important to safety, redundancy should be provided. If the control function that would initiate a shutdown is not redundant, it shall be designed for an automatic fail-safe followed by a shutdown. 

In addition, die following typical parameters may be desirable or neeessaiy to measure depending on the system design  

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An extruder for a polymer was controlled by a microprocessor based data acquisition and control system. The CAMILE system (Control And Monitoring Interface for Laboratory Experiments) connects the sensors and control elements of the extruder to a host MS-DOS computer. While a variety of variables are measured and controlled, this paper will consider only temperature control. 

Deep refrigeration Ice making Thermal expansion Compatibility of materials Gas liquefaction Refrigerants and gases System control and monitoring Vapor-compression circuits Absorption systems... 

As subsea production systems are remote from the host production facility there must be some type of system in place which allows personnel on the host facility to control and monitor the operation of the unmanned subsea system. 

Phosphoric acid [7664-38-2] is rarely used because of cost and disposal problems. Nitric acid [7697-37-2] is to be avoided because it is known to cause catastrophic damage to resin, equipment, and personnel if appropriate controls and monitoring systems are not installed. 

Entry into Confined Spaces. In 1993 OSHA adopted a confined space entry rule (93) requiring employers to evaluate the workplace to (/) determine if it contains any confined spaces, (2) mark or identify such confined spaces, and (2) develop and implement a permit program for entry into such spaces. The program must include a permit system which specifies the steps to be taken to identify, evaluate, control, and monitor possible electrical, mechanical, and chemical ha2ards select and use equipment institute stand-by attendance and estabflsh communications. The reference standard (93) should be studied for details. 

Historical DataBase Subsystem We have discussed the use of on-hne databases. An historical database is built similar to an on-line database. Unlike their on-line counterparts, the information stored in a historical database is not normally accessed directly by other subsystems for process control and monitoring. Periodic reports and longterm trends are generated based on the archived data. The reports are often used for long-term planning and system performance evaluations such as statistical process (quality) control. The trends may be used to detect process drifts or to compare process variations at different times. 

To save energy, many HVAC systems employ a mechanism for regulating the flow of outdoor air called an economizer cycle. An economizer cycle takes advantage of milder outdoor conditions to increase the outside air intake and in the process reduces the cooling load on the system. Controlling the rate of flow of outdoor air appears simple, in theory, but often works poorly m practice. The small pressure drop required to control the flow rate of outdoor air is rarely controlled and monitored. Quite often, the damper system used to regulate the airflow is nonfunctional, disconnected from the damper actuators, or casually adjusted by building operators (Institute of Medicine, 2000). 

LECTRIC POWER, SYSTEM PROTECTION, CONTROL, AND MONITORING OF... 

See also-. Climatic Effects Consumption Domestic Energy Use Electric Motor Systems Electric Power, Generation of Electric Power, System Protection, Control, and Monitoring of Electric Power Substations Electric Power Transmission and Distribution Systems Government and the Energy Marketplace Regulation and Rates for Electricity. 

Electric Power, System Protection, Control, and Monitoring of... 

In some systems, central computerized control and monitoring equipment. 

Manufacturers now offer as standard microprocessor-based control systems as part of their gas turbine generator set. The set can therefore be controlled and monitored from panels adjacent to the machine or, if required, remotely from a central control room. In combined-cycle installations, the system would be linked into the... 

In general, aboveground treatment systems can be more readily controlled and monitored to optimize the removal of MTBE and other oxygenates than in situ treatment systems. 

The first STM experiments were performed under UHV conditions, and so the bias potential was simply applied as a difference across the tip and sample. However, introducing an electrolyte above the sample brought with it some particular problems. It is no longer sufficient simply to apply a bias voltage equal to the potential difference between tip and sample as this means that the potentials of the tip and sample are undefined with respect to any fixed reference, a wholly undesirable situation. Consequently, modern electrochemical STM systems operate under bipotentiostatic control with the tip and sample controlled and monitored independently with respect to the reference electrode. The bias potential is then still given by (Fs — FT), but VT and Fs are now potentials with respect to the reference electrode. 

An automated system, by definition, should perform a required act at a predetermined point in the process and should have a self-regulating action. This implies that intervention by the analyst is not required during the procedure and that only those systems that incorporate a microprocessor or computer to control and monitor their performance can be designated as automated. Some systems may not comply strictly with this definition but are a valuable means of mechanizing laboratory activities. 

Simply, SCADA is a computer-based control system that remotely controls processes previously controlled manually. The philosophy behind SCADA control systems can be summed up by the phrase, If you can measure it, you can control it. SCADA allows an operator using a central computer to supervise (control and monitor) multiple networked computers at remote locations. Each remote computer can control mechanical processes (mixers, pumps, valves, etc.) and collect data from sensors at... 

This is based on a sample fast loop with a sample take-off probe in the main process line, and a retnm to either a pnmp-snction or ambient pressnre sample recovery system (Fignre 5.22). The fast loop provides a filtered slip-stream to the analyzer, along with flow control and monitoring (low-flow alarm), and freqnently some form of sample antograb facility for sample capture. The slipstream flow to the internal analyzer sample flow cell is relatively low volnme and allows for a very high degree of sample temperature control (typically... 

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