Over the last half of the 20th century, control valve design has advanced rapidly. Adding to the traditional butterfly and globe valves has been the advent of the modulating V'ball valves, eccentric disc rotary valves and the high performance eccentric disc butterfly valves, amongst others, adding to the choices of modulating control valves.
In parallel with this, there has been advancements in the design of valve trims, often customised for specific customer applications, to combat the effects of cavitation, excessive sound pressure levels, clogging etc.
Advancement of positioning devices towards digital valve controllers has allowed more responsive control and an insight to the valves operational health as never seen before. From the comfort of an office users can now download data direct from a valve, remotely situated in the plant, in sufficient quantity to permit valued judgements as to whether the unit needs to undergo maintenance or not.
Industry demands require that plants run longer between shutdowns and that process variability is reduced to a minimum to yield product of a consistent quality at a lower cost. Faced with an ever increasing range of valves available in the market and probably an ever dwindling maintenance budget, the plant engineer needs to be sure that the selected valve will give him the best return on his investment over time. In order to be able to fully evaluate the equipment on offer the engineer needs to be able to make judgements on the following questions, amongst others:
p Is the valve trim offered, in respect of materials and design, capable of fulfilling the duty for which it is intended without undue wear?
p Will the selected inherent characteristic give the required installed characteristic that is suitable for the required control range and reduce process variability?
p Does the valve in question contain the high performance attributes that will allow for fast and accurate response, and hence reduced process variability?
p Does the positioning device give the required accuracy of control, again to reduce process variability?
Fisher Controls says that it has long understood the need for the customer to maximise his investment by obtaining a fuller understanding of control valve engineering. In view of this, its Educational Services department (FRES) has successfully run a course (Control Valve Engineering 1) to satisfy this need. The course is constantly reviewed to allow the student access to the latest advances in technology.
It is becoming essential for maintenance departments within companies to ensure that equipment is well maintained to meet the increased demands required on it. FRES has an in depth course designed for technicians (Valve Technician 1) to enable them to competently maintain and calibrate the valves on the plant.
Alpret Control Specialists, representing Fisher Controls in southern Africa, has committed itself to the process of education within the industry. The aforementioned courses, amongst others, are now locally available and are presented by local instructors certified by Fisher Controls, Marshalltown, Iowa, USA.
Alpret Control Specialists
(011) 474 0356
| Tel: | +27 11 249 6700 |
| Email: | [email protected] |
| www: | www.acs-autocon.com |
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