MAINTENANCE AND CALIBRATION CONTROL VALVE
By Zul Fazri S.M.MAINTENANCE AND CALIBRATION CONTROL VALVE
Control ValveIn an automatic control system, Control Valve is
the final control elements that embody the output signal from the
controller becomes a movement valve opens or closes the flow so as
to return the process variable to a predetermined price.In general
function a control valve are:On-Off: Open and close the flow
(solenoid valve).
Variable Control: set the size of the flow.
Safety: as a safety process.
General Form of Control ValveBroadly speaking, the control valve
comprises:Actuator
Bonnet
Body
PART OF ACTUATOR:ActuatorDiaphragm CaseDiaphragm Diaphragm
PlateActuator StemActuator SpringSpring SeatSpring AdjustorYokeStem
ConnectorTravel IndicatorTravel Indicator Scale
Action Control ValveDirect ActionReverse Action
Bonnet AssemblySeveral types of bonnet are: Extension Bonnet
Bellows Seal Bonnet
Finned Bonnet
Packing and LubricationBonnet is the portion of control valve
that contains the packing box and stem seal and may guide the stem.
It provides the principal opening to the body cavity for assembly
of internal parts or it may be an integral part of the valve body.
It may also provide for attachement of the actuator to the valve
body. Typical bonnets are bolted, threaded, welded,
pressure-sealed, or integral with the body.(ANSI/ISA 75.05.01-2000
(R2005))Figure Types Of Bonnet are:Extension BonnetFinned
BonnetBellow Seal BonnetPacking and Lubrication
Valve BodyValve body or valve body assembly refer to ANSI/ISA
75.05.01 define as the main pressure boundary of the valve that
also provides the pipe connecting ends and the fluid flow
passageway, and supports the valve trim.
Types of Valve Body:Globe valveNeedle Valve bodies ( bars stock
valve bodies)Ball valve bodiesButterfly valve BodyDiaphragm
(sounders type) valve bodiesDrag valve bodies
Globe Valve
Butterfly Valve Body
Needle Valve BodyDiaphragm (sounders Type) Valve BodiesBall
Valve BodyDrag Valve Bodies
Maintenance and Calibration Control ValveMaintenance
PhilosophyCorrectiveAction is taken after an event has accurerred.
Wait for something to happen to a valve and then repair or replace
it.
PredictiveAction is taken based on the life time the
equipment.PreventiveAction is taken on a timetable based on
history. Try to prevent something bad from happening.Maintenance
ProcessManufacturers Literarture (disassembly of a control valve,
inspecting the disassembled control valve, cases and solving
problem control valve).
Actuator Diaphragm (stem packing and seat rings).
Grinding Metal Seats (replacement control valve parts,
reassembly of the control valve, and reinstalling the control
valve).CalibrationCalibration instrument is process or procedure of
adjusting an instrument so that its indication or registration is
in close agreement with a referenced standard.Calibration
EquipmentAir CompressorPresure RegulatorStandart GagesHydrostatic
PumpTest Bench
Control Valves Name PlateRead the information that to be written
on name plate carefully.Name plate has special information about
valve and actuator. The important which is printed on name plate as
follow.
SummaryBased on discussion about Maintenance and Calibration
Control Valve, summary as the following:Control valve has three
function, there are:On OffVariabel controlSafetyControl valve has
three main part, there are:Actuator as activatorBonnet as a
coupling between body and actuatorBody valve as which is directly
contact with media that is controlledMainteance Control Valve,
there are:Manufacturers LiteratureActuator DiaphragmGrinding Metal
seat
Calibration Control Valve is process or procedure of adjusting
an instrument so that its indication or registration is in close
agreement with a referenced standard.
THE ENDThank You for Your Attention
Bellow Seal BonnetBonnet ini digunakan bilamana tidak
diperbolehkan ada kebocoran sepanjang yang dapat ditolerir.Biasanya
digunakan bilamana fluid proses adalah racun, mudah terbakar, mudah
menguap, radioaktif, atau material-material yang mahal. Oleh sebab
itu pemilihan bellow seal bonnet harus benar-benar diperhatikan
dengan hati-hati.
Extention BonnetDigunakan untuk temperatur tinggi atau rendah
sehingga packing stem terhindar dari temperatur yang extrim
tersebut. standart packing yang umum digunakan dengan temperatur
kerjanya sampai 4500 F (2320 C) tetapi mudah rusak pada temperatur
rendah. Extention bonnet dapat memindahkan packing box dari bonnet
agak jauh untuk mencegah terhadap temperatur yang terlalu rendah
dari proses sehingga temperatur dari packing berada pada range yang
diinginkan.
. Finned BonnetUmumnya packing material dibatasi penggunaannya
karena temperatur yang tinggi. Untuk melayani kebutuhan temperatur
tinggi digunakan packing yang tahan temperatur tinggi atau dengan
menggunakan Finnet bonnet seperti pada gambar., yang bertujuan
untuk memperbesar luasan sehingga panas dapat dibuang dengan
mudah.
Packing dan LubricatingPacking yang paling banyak digunakan
sebagai bahan untuk packing karena mempunyai kemampuan pelumasan
sendiri (selflubricating) dan tidak perlu diberi minyak.
Input SignalOutput
ATO (Fail Close)ATC (Fail Open)
15 psi
9
3 Open Close (Full Close) 100% 100%
50%50% 0 CloseOpen 0
