Azbil VDC User manual

Diaphragm Control Valve
Model: VDC, VAC, VST,VAA
ANSI Class 600 or under
User’s Manual
OM2-8110-0300
13th edition

Copyright, Notices and Trademarks
©2001-2023 Azbil Corporation All Rights Reserved.
While this information is presented in good faith and believed to
be accurate, Azbil Corporation disclaims the implied warranties of
merchantability and tness for a particular purpose and makes no
express warranties except as may be stated in its written agree-
ment with and for its customer.
In no event is Azbil Corporation liable to anyone for any indirect,
special or consequential damages. This information and speci-
cations in this document are subject to change without notice.

Model MTG11A/18A, MTG11B/18B, MTG14C i
Safety Guide
1 : Nomenclature of parts
Diagrams with the control valve terminologies and words used in this manual are
shown below. Please familiarise yourself with these denitions before using the
device.
Diaphragm
Yoke
Bonnet
Valve body
Flange
Actuato
r
Figure S-1 Nomenclature of globe valve
Body
Valve body
(Vane or disk)
Link
Actuato
r
Figure S-2 Nomenclature of buttery valve

Safety Guide Azbil Corporation
ii Model MTG11A/18A, MTG11B/18B, MTG14C
2 : Safety precautions
Please read this section before using the valve to ensure proper handling.
WARNING
If the stated procedures are not followed as specied, a potentially hazardous situation
may arise, which could result in death or serious injury.
CAUTION
Failure to observe these cautions may create dangerous conditions that could result in
injury to the personnel and/or in physical damage to the device.
3 : Verication of Valve Specications and Precautions on Storage
3-1 : Unpacking
Control valve is a precision equipment. Handle it with care to avoid damaging it.
When unpacking, check that the following items are in the crate:
• Main valve body, actuator and accessories as ordered,
• Additional equipment as ordered. Installation options
3-2 : Verication of specications
Please check and see if that the process ow uid conditions, and valve Tag No.
agree with the specications that were ordered. The nameplate of each product are
found as shown below. (Other products have their nameplates attached to the identical
positions.)
Figure S-3 Position of nameplate on V Series

Azbil Corporation Safety Guide
Model MTG11A/18A, MTG11B/18B, MTG14C iii
Compliance with Regulations
This product complies with the directive below.
• Pressure Equipment Directive (PED) 2014/63/EU
Requirements for workers (installation, operation, maintenance)
To ensure safety, only specialists who are skilled in instrumentation work should
carry out the installation, operation, and maintenance of this device.
Cautions on storage
When storing the control valve, pay attention to the following precautions:
• A control valve that has been packed in a cardboard box should be stored indoors
at normal temperature and humidity.
• A control valve that has been packed in a wooden crate should be stored indoors
at normal temperature and humidity as a rule. In the event outdoor storage, open
the crate, verify the specications of the unit and cover it with a polyethylene
protective sheet to guard against precipitation.
• When storing a used valve, follow the procedures described below:
(1) Flush out the process uid from inside the valve body and dry,
(2) When there is a possibility of the valve body rusting, preservation treatment
should be given,
(3) To prevent water from getting into the instrument, cover pneumatic tubing
connection and electric connector with watertight caps or tape. Also, protect
the connector threads,
(4) Place a ange cap onto the end of the pipe connecting surface (ange face,
butt welding connections) to avoid any possible damage.

Safety Guide Azbil Corporation
iv Model MTG11A/18A, MTG11B/18B, MTG14C
4 : Installation
4-1 : Installation environments
CAUTION
• Ensure sucient space for easy and
safe operation and maintenance of
the control valve.
• Avoid installing the valve in a
location where vibration or external
stress may impair proper valve
functions. If necessary, make
appropriate provisions against these.
• Consider providing a support for
the valve, so that the process piping
is not burdened with the excessive
weight of valve, or provide supports
on the upstream and downstream
pipe runs.
• Provide a cover or protective fence
around the valve installation, when
a valve is installed facing a path
or if physical contact with valve is
expected.
• Do not install a valve where it is
submerged under the water, or snow or freezing may take place.
• Provide a wall for protection against heat radiation.
• Provide measures to protect the valve against salt spray or corrosive atmosphere.
• To stop operation of the Flowmeter:
- Switch the control equipment connected to the owmeter to manual control.
- To turn the power to the converter o.
CAUTION
• In order to guard against accident while handling the valve, always wear safety
gloves, goggles and safety shoes.
Pipe support
Maintenance space

Azbil Corporation Safety Guide
Model MTG11A/18A, MTG11B/18B, MTG14C v
Prior to installation work, follow the items of caution as described below:
CAUTION
• Check and conrm that there is no external
damage to the valve (body, actuator,
accessories).
• Check and conrm that there is no damage
on pipe connecting anges or butt welding
connections.
• Ensure that the temperature of welded part
of pipe has been reduced before proceeding.
• Make sure that the anges on pipe have been
chamfered.
• Remove dust, sand, welding spatter or any
other foreign matter from the pipe and
clean out pipe. Any foreign matter will
damage the valve seat and reduces shut-o
characteristics.
• Ensure that upstream and downstream pipe
supports are suciently strong. Otherwise,
the valve's weight may cause leakage from
ange connections.
Y
Scar
Dirt, sand
WARNING
• Operation of valve over and beyond the
rated pressure or connection other than
recommended of specied connection may
cause damage or leakage which may result
in serious injury.
Y

Safety Guide Azbil Corporation
vi Model MTG11A/18A, MTG11B/18B, MTG14C
4-2 : Installation work
CAUTION
• Ensure that centers of upstream and downstream pipes are aligned when pipe
installation has been completed. Any mis-alignment of pipe will distort the valve
and will cause leakage from the connections. (Gasket)
• Make sure that the face to face dimension of pipe anges is equal to face to face
dimension of valve body plus gasket thickness.
• When installing a buttery valve on a pipe, keep the valve body (vane or disk) in
the fully closed position. When lifting a valve using the eyebolts on the actuator,
make sure that the rated weight of the bolt does not exceed the limit given in
the instruction manual. A load in excess of the limitation will cause damage to
actuator or will result in air leakage.
• Use proper gaskets for pipe anges. Otherwise, process uid may leak. Always
use new gaskets for pipe anges that will meet process uid specications,
temperature and pressure
conditions. Otherwise
process uid leakage
may occur.
• When ushing pipes,
keep valve in the fully
open position and do not
stroke valve. Welding
spatter or foreign matter
may damage valve.
WARNING
When installing a valve on
a pipe, keep hands and feet
away from valve body's
bottom or from between
anges to avoid physical
injury.
When reinstalling the
valve after inspection,
maintenance or
modication, ush out
process uid remaining in
the pipe or replace it with
safer liquid.
Weight
limit
1
2
3
4
Tighten diagonally

Azbil Corporation Safety Guide
Model MTG11A/18A, MTG11B/18B, MTG14C vii
4-3 : Pneumatic piping and electric work
CATUTION
• Pneumatic tubing should be sized so as not to
cause dropping of air pressure when the control
valve is in operation. Pneumatic tubing should
have an allowance in bend (use specialized
tool) and the parallel tubing should be clamped
together.
• Only qualied persons should do electrical
work in accordance to electrical facility
engineering standards.
• Cable connections should be made to conform
to the facility's conditions. A suitable adaptor
or packing should be selected to suit the outer
dimension of the completed installation.
• When using seal tape on pneumatic tubing, do
not apply tape on the rst two threads from
the tip of connector. This may block the air
passage and cause malfunction of the valve.
• When using liquid packing (seize lock) on
pneumatic tubing, care should be exercised
so the liquid does not leak into tubing. It
may block the air passage, resulting in valve
malfunction.
• Avoid electrical work in rainy weather or at a
time of high humidity. Any intrusion of water
into connector or terminal will cause rusting
and electrical leakage.
• Covers of accessories such as the positioner are
provided with a seal packing (gasket). Exercise
care so as not to misplace or lose them while
electrical work is in progress.
• Exercise care so as not to lose xing screws
of accessories such as the positioner. When
tightening screws, ensure that packing is in
place and tighten screws with an even torque.
• Cable threads and conduit seal should be
tightened so as to ensure that water does not
get in.
Y
Seal
tape
Two threads
Liquid run
Positioner

Safety Guide Azbil Corporation
viii Model MTG11A/18A, MTG11B/18B, MTG14C
5 : Caution on disassembly and reassembly
5-1 : Disassembly
CATUTION
• When disassembling a spring-
incorporated positioner, follow the
prescribed procedure in removing
bolts and nuts. Otherwise, the spring
may pop out and could resulting in
physical injury.
• When the eye-bolts of actuator are
used to lift the valve from the pipe,
ensure that the weight limit given
in manual is adhered to. Otherwise,
there is the danger of dropping the
valve,
• When removing the trim (inner
valve) from the body, ensure that
the proper type of specialized tool is
used. Refer to the instruction manual
for the tools that should be used.
Otherwise, the trim may be damaged.
Y
Eye bolt
Spring
HTS
2-inch
Specialized
tool
Weight
limit
Suspending
Y
Stop
valve
Reducing
valve
Close Open
WARNING
• Before disassembling the valve,
ensure that the pressure within piping
has been reduced to atmospheric
pressure. Flow out of process uid
may cause physical injury.
• When disassembling the valve,
ush out the interior of the valve
or replace the uid inside. Residual
process uid may cause physical
injury,
• Do not disassemble the pneumatic
actuator with supply air on.
Compressed air may cause physical
injury.

Azbil Corporation Safety Guide
Model MTG11A/18A, MTG11B/18B, MTG14C ix
6 : Assembly
CATUTION
• When assembling the spring loaded
actuator, adhere to the order of
assembly procedure; install bolts
and nuts as instructed. Disregard of
procedure may result in malfunction.
• When installing a buttery valve
on a pipe line, fully close the valve
(vane or disk). Tighten ange bolts
and nuts diagonally and with even
torque.
• When installing the valve body,
always use new gaskets. Old or
reused gaskets may cause leakage
• When assembling trim (inner valve),
ensure that specialized tools are
available and use only those which
meet specications.
Follow assembly procedure
Install buttery valve in fully closed
position
Tighten diagonally
1
2
3
4
Replace packing / gasket
WARNING
• When assembling the valve, tighten
bolts and nuts at a torque as specied
in instruction manual. Any damage
or corrosion on the bolts or nuts may
cause destruction of control valve
which will lead to physical injury.
Always replace defective bolts and
nuts with new ones.

Safety Guide Azbil Corporation
x Model MTG11A/18A, MTG11B/18B, MTG14C
7 : Maintenance and inspection
Adhere to the following warnings and cautions while conducting maintenance or
inspection.
CAUTION
If there is leakage from a valve, do not come close to the valve until safety is assured
of. A serious accident or physical injury may occur depending on the type of uid.
WARNING
• Check the gland daily and ensure that there is no leakage from it. Check valve
operation daily, and conrm that it is not hunting.
• Make sure that there is no abnormal vibration or noise during operation,
• When the valve is repaired or disassembled, old parts should be properly disposed
of as industrial waste. Otherwise, they may contaminate the environment.
Check scale
Check for hunting
Inspect gland (leakage)
Inspect gland
connection (leakage)
Check for abnormal
noise or vibration
Figure S-4

VDC, VAC, VST, VAA - Diaphragm Control Valve 1
Table of Contents
Safety Guide
1 : Nomenclature of parts ......................................................................................... i
2 : Safety precautions...............................................................................................ii
3 : Verication of Valve Specications and Precautions on Storage........................ii
4 : Installation .......................................................................................................... v
5 : Caution on disassembly and reassembly...........................................................ix
6 : Assembly............................................................................................................ x
7 : Maintenance and inspection...............................................................................xi
Chapter 1 : General
1-1 : Specication of Control Valves .................................................................... 1-2
1-2 : Construction................................................................................................. 1-2
1-3 : Valve Body Section...................................................................................... 1-2
1-4 : Actuator........................................................................................................ 1-2
Chapter 2 : Installation of a Control Valve
Chapter 3 : Inspection and Maintenance of Control Valves
3-1 : Inspection Before Starting Operation........................................................... 3-1
3-2 : Periodical Inspection and Maintenance ....................................................... 3-1
3-3 : Lubrication of Gland Packing (for valve with asbestos packing)
(See Figure.3-1)........................................................................................... 3-2
Chapter 4 : Control Valve Adjustment
4-1 : Lift Adjustment ............................................................................................. 4-1
4-2 : Spring Compression Adjustment ................................................................. 4-2
4-3 : Positioner Adjustment .................................................................................. 4-2
Chapter 5 : Disassembly and Reassembly
5-1 : Disassembly................................................................................................. 5-1
5-2 : Reassembly ................................................................................................. 5-1
5-3 : Disassembly and Reassembly of Bellows-sealed Valve.............................. 5-2
Chapter 6 : Parts Replacement
6-1 : Replacement of Gland Packing ................................................................... 6-1
6-2 : Replacement of valve plug and Cage of VDC or VAC Control valve........... 6-3
6-3 :
Replacement of valve plug and seat ring of VST, VAA, or VAV Control Valve ... 6-4
6-4 : Diaphragm Replacement of Diaphragm Motor (See Figure 1-6, 1-7.) ......... 6-5
6-5 : O-ring Replacement of Diaphragm Motor (See Figure 1-6, 1-7.)................. 6-6
6-6 : Disassembly and Assembly of Model PSA6 Actuator.................................. 6-7

Table of Contents Azbil Corporation
2 VDC, VAC, VST, VAA - Diaphragm Control Valve
Chapter 7 : Manual Handwheel (Side Handwheel of Actuator)
7-1 : Operation Method ........................................................................................ 7-1
7-2 : Installation.................................................................................................... 7-1
7-3 : Disassembly and Reassembly..................................................................... 7-1
Chapter 8 : Trouble shooting
Chapter 9 : Recommended Spare parts
9-1 : Major replacement parts .............................................................................. 9-1

VDC, VAC, VST, VAA - Diaphragm Control Valve 1-1
Chapter 1 : General
This manual covers the instruction for the Cage type Double Seated Control Valves
(Model VDC), Cage type Angles (Model VAC), Top Guiding SIngle Seated Control
Valves (Model VST) and Acorn type, Angle Control Valves (Model VAA).
Model: VDC
Cage type Double Seated Control Valve
(Rating: ANSI 600lb or Less)
Model: VST
Top Guiding Single Seated Control Valve.
(Rating: ANSI 600 lb. or Less)
Model: VAC
Cage type Angle Control Valve
(Rating: ANSI 600 lb. or Less)
Made: VAA
Acorn type Angle Control Valve
(Rating type Angle 600lb or Less)

General Azbil Corporation
1-2 VDC, VAC, VST, VAA - Diaphragm Control Valve
1-1 : Specication of Control Valves
The basic model number, valve size, pressure rating and other related specications
of the control valve is indicated on its nameplate. (See Figure 1.) Please conrm that
the process ow condensations the specications match before installation.
Figure 1-1 Nameplate
1-2 : Construction
Control Valves consist of two major sections - valve body and diaphragm actuator.
Di󰀨erent combinations of valve body and actuators, type of connections, types of
materials and other specications result in a control valve that optimally suits the
requirements of process ow control.
1-3 : Valve Body Section
The valve body section consists of a bonnet, a valve plug, a cage or a seat ring, and
other trim parts. The bonnet is assembled to the valve body with stud bolts, nuts and
with gasket, to provide a pressure - tight valve body section. The valve plug in the
valve body is moved up and down by the actuator through the valve stem, thereby
varying the opening formed between the plug and cage or seat ring to control the
amount of ow. (See Figures 1-2 through 1-5.)
1-4 : Actuator
The actuator is a spring - loaded diaphragm motor. It converts a pneumatic input
signal into a mechanical positioning force with its spring and diaphragm, in order
to drive and hold the valve plug at a position corresponding to the pneumatic input
signal. (See Figure. 1-6, 1-7.)
~Note “Air- O-Motor” is Azbil Corporation's trade name for its diaphragm motors
(Models VA1 to 5).

Azbil Corporation General
VDC, VAC, VST, VAA - Diaphragm Control Valve 1-3
Figure 1-2 Model: VDC Cage type Double Seated Control Valve (Rating: ANSI 600 lb. or less)
Item no. Parts Item no. Parts
1 Valve stem 13 V Packing retainer
2 Stud bolt 14 V Packing spring
3 Nut 15 Blind plug
4Packing ange 16 Packing ring
5Yoke nut 17 Stud bolt
6 Bonnet 18 Nut
7Gasket 19 Gasket
8 Valve plug 20 Valve body
9 Cage 21 Drain plug
10 Packing follower 22 Lubricator
11 V Packing Holder 23 Latern ring
12 V PTFE packing 24 Packing

General Azbil Corporation
1-4 VDC, VAC, VST, VAA - Diaphragm Control Valve
Figure 1-3 Model: VAC Cage type Angle Control Valve (Rating: ANSI 600 lb. or less)
Item no. Parts Item no. Parts
1 Valve stem 13 V Packing retainer
2 Stud bolt 14 V Packing spring
3 Nut 15 Blind plug
4Packing ange 16 Packing ring
5Yoke nut 17 Stud bolt
6 Bonnet 18 Nut
7Gasket 19 Gasket
8 Valve plug 20 Valve body
9 Cage 21 Drain plug
10 Packing follower 22 Lubricator
11 V Packing Holder 23 Latern ring
12 V PTFE packing 24 Packing

Azbil Corporation General
VDC, VAC, VST, VAA - Diaphragm Control Valve 1-5
Figure 1-4 Model: VST Top guiding Single Seated Control Valve (Rating: ANSI 600 lb. or Less)
Item no. Parts Item no. Parts
1 Valve stem 15 V packing spring
2 Stud bolt 16 Blind plug
3 Nut 17 Packing ring
4Packing ange 18 Stud bolt
5Yoke nut 19 Nut
6 Bonnet 20 Valve plug
7Pin 21 Seat ring
8 Guide bushing 22 Valve body
9Gasket 23 Drain plug
10 Guide ring 24 Lubricator
11 Packing follower 25 Lantern ring
12 V packing holder 26 Packing
13 V PTFE packing 27 Guide
14 V packing retainer

General Azbil Corporation
1-6 VDC, VAC, VST, VAA - Diaphragm Control Valve
Figure 1-5 Model: VAA Acorn type Angle Control Valve (Rating: ANSI 600lb or less)
Item no. Parts Item no. Parts
1 Valve stem 15 V packing spring
2 Stud bolt 16 Blind plug
3 Nut 17 Packing ring
4Packing ange 18 Stud bolt
5Yoke nut 19 Nut
6 Bonnet 20 Valve plug
7Pin 21 Seat ring
8 Guide bushing 22 Valve body
9Gasket 23 Drain plug
10 Guide ring 24 Lubricator
11 Packing follower 25 Lantern ring
12 V packing holder 26 Packing
13 V PTFE packing 27 Guide
14 V packing retainer