Manual controls

The determining of sorting limits of steel parts after thermal processing in order to eliminate these, which indicate exceeded allowed content of residual austenite, requires elements of identical shape and dimensions, as the studied parts, and with known content of residual austenite. Such elements serve to define the sorting thresold, during manual control as well as automatic... 

Correlation between amplitude or equivalent square data of manual control and defect height showed by AUGUR 4.2 was poor. 

Fractional distillation. Fig. II, 60, 2 illustrates a set-up for fractional distillation wdth a Hempel-type column and cold finger, the latter to give manual control of the reflux ratio. Any other fractionating colunm, e.g., an all-glass Dufton or a Widmer column may, of course, be used. 

Overall, WebLab MedChem Explorer is very easy to use. The stepwise job setup works well, assuming that all users will be following a conventional drug rehnement process. It is not a program that can be used for complex simulations requiring the researcher to manually control many details of the simulation. 

Control Devices. Control devices have advanced from manual control to sophisticated computet-assisted operation. Radiation pyrometers in conjunction with thermocouples monitor furnace temperatures at several locations (see Temperature measurement). Batch tilting is usually automatically controlled. Combustion air and fuel are metered and controlled for optimum efficiency. For regeneration-type units, furnace reversal also operates on a timed program. Data acquisition and digital display of operating parameters are part of a supervisory control system. The grouping of display information at the control center is typical of modem furnaces. 

Operating Labor Centrifuges run the gamut from completely manual control to fully automated operation. For the former, one operator can run sever centrifuges, depending on their type and the apphcation. Fully automatic centrifuges usually require little dirert operation attention. 

Monitor BPCS for deviations and provide operators with ability to assume safe manual control... 

I Manual control This is throuah switching devices... 

Manual control systems, 356 Marine type gear coupling, 16... 

A process waste heat boiler was damaged when the control operator inadvertently closed the cooling water valve when he intended to open it. The manual control knob turned in the opposite direction from most of the other valves in the plant—the L, cooling water valve was air to close—most control valves were air... 

The manual individual burner valves on the boiler that exploded were not closed when the boiler shut dnw n. After the purging fuel gas was admitted to the header from remote manual controls in the control room and min the... 

Air terminal unit Air distribution equipment that provides set conditions by the mixing of primary and secondary air. The device may be fixed, having no control or means of manual adjustment, automatically controlled or manually controlled. If automatically controlled, a sensor is used to indicate any required... 

Unauthorized interference with computer hardware is usually difficult, but interference with peripheral equipment may be more serious than on a traditional plant, as the computer will not know that interference has occurred. For example, the leads on a limit switch on a valve were interchanged to carry out some tests. The plant was on manual control at the time but was switched back to computer control before the leads were restored to their coirect positions. The computer thought the valve was open (when it was shut) and elected to close it. It actually opened it, releasing flammable material [2]. 

On the boiler that exploded the manual individual burner valves were not closed when the boiler shut down. After the purge period, fuel gas was admitted to the header from remote manual controls in the control room and into the firebox. Low fuel gas pressure tripped the master safety valve after each attempt to pressure the fuel header. Three attempts were made to purge the boiler and on each of these occasions fuel gas was dumped into the furnace through the open manual burner gas valves. On the third attempt a severe explosion occurred. 

Human Factors Engineering/Ergonomics approach (control of error by design, audit, and feedback of operational experience) Occupational/process safety Manual/control operations Routine operation Task analysis Job design Workplace design Interface design Physical environment evaluation Workload analysis Infrequent... 

This form of implanned manual operation is unsatisfactory on a number of counts. The fact that the operator may normally be insulated from the process by the automatic control systems means that he or she will probably not be able to develop the knowledge of process dynamics ("process feel") necessary to control the system manually, particularly in extreme conditions. Also, the fact that manual control was not "designed into" the systems at the outset may mean that the display of process information and the facilities for direct control are inadequate. A number of techniques are available to assist designers in the allocation of function process. Some of these are described in Meister (1985). In a paper entitled "Ironies of Automation" Bainbridge (1987) notes four areas where the changed role of the human in relation to an automated system can lead to potential problems. These will be discussed below. 

Documents such as job descriptions, operating manuals, emergency procedures, accident, and "near-accident" records, can be useful sources of information about the task to be studied. Pipework and instrumentation diagrams can also be used to gain an insight into the complexity of the process, the type of control loops installed, and the process parameters to be manually controlled by the workers. 

In this case, the operations within a sequence are further defined according to various criteria such as whether they involve reception or transition of information, storage of information, manual control responses, inspections, and decisions. However, some other dimensions of an operation may require particular emphasis such as whether information is transmitted electronically, by external communication etc. A type of vertical axis can still be used to represent sequential order and if required this can incorporate the same timing information as temporal OSDs. 

This technique is derived from a method developed by electrical engineers to facilitate the analysis of electrical networks. It has been applied to process operator studies by Beishon (1967). The method describes the process to be controlled in terms of "manually controlled" variables, "displayed" variables and "hidden" variables which can be deduced from those displayed or from... 

Manual Controls. The first methods used in energy control involved human intei vention. The operator was the sensor (i.e., using his eyes, ears, and hands or using additional devices to quantify the values of the controlled variables), and he was also the actuator controller. The control of the processes was slow and vei y ineffective. For example, in an old steam engine control the human operator sees the instantaneous pressure and then manually regulates the power of the device (e.g., by adding fuel to a boiler). But in today s industrial reality, this control is not only ineffective but in most cases is not possible. 

Mechanical switches provide a simple manual interface to operate all sorts of loads, but they suffer from all the drawbacks of manual control, namely in terms of speed of response, and also requiring permanent operator awareness. 

Capacitors as bulk units can be connected to the supply busbar via a fuse switch, molded-case circuit breaker of air circuit breaker. In this type of installation control is purely manual, and in cases of a reasonably constant load and where the amount of power factor correction is limited such a manually controlled system is perfectly adequate. The supply authority may, however, require to be informed that a capacitor bank is permanently connected to the supply. Capacitors are more generally connected either in banks controlled from a VAR sensitive relay or across individual loads (e.g. motors). 

Low-level ventilation openings, whether windows, doors or ventilators, are generally manually operated for simplicity and economy, allowing personnel to control their own environment. High-level openings can also be manually controlled by means of rod or cable operation, although this has generally lost favor (except in the case of simple windows) and automatic operation is preferred. 

If a fluid power system is properly designed and used, it will provide smooth, flexible, uniform action without vibration, and is unaffected by variation of load. In case of an overload, an automatic release of pressure can be guaranteed, so that the system is protected against breakdown or excessive strain. Fluid power systems can provide widely variable motions in both rotary and linear transmission of power and the need for manual control can be minimized. In addition, fluid power systems are economical to operate. 

The reactor or stripper catalyst level controller is controlled with a level controller that regulates the movement of the spent catalyst slide valve. The regenerator level is manually controlled to maintain catalyst inventory. 

Manually Controlled System A manually controlled system comprises one or more transformer-rectifiers each with its associated control panels which supply the d.c. to the various anodes installed in the water box spaces. Each transformer-rectifier is provided with its own control panel where each anode is provided with a fuse, shunt and variable resistor. These enable the current to each anode to be adjusted as required. Reference cells should be provided in order to monitor the cathodic protection system. In the case of a major power station, one transformer-rectifier and associated control panel should be provided for separate protection of screens, circulating water pumps and for each main condenser and associated equipment. 

---