IMI STI RTC Series User manual

Quarter turn pneumatic actuator
RTC Series
Double acting version type RTC
Single acting version type RTCS
INSTRUCTION MANUAL 5100

_____________________________________________________________________________________
STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5100, rev. 06 06/2020 – RTC/RTCS
i
Date Revision Description Author Approval
10/06/2020 6 Revised Nameplate (Section 4) G. Alfieri A. Negri
05/09/2016 5 Revision M. Bozzarelli F. Tondolo
15/02/2016 4 Revision M. Bozzarelli D. Lamoure
22/09/2015 3 Revision M. Bozzarelli D. Lamoure
22/07/2013 2 Revision G. Alfieri D. Lamoure
11/07/2013 1 Revision G. Alfieri D. Lamoure
02/10/2012 0 Issue PGA engineering D. Lamoure
STI S.r.l has taken every care in collecting and verifying the documentation contained in this Instruction
Manual. The information herein contained are reserved property of STI S.r.l.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS
ii
INDEX
1 GENERAL INFORMATION................................................................................................................................ 1
1.1 G
ENERAL
W
ARNINGS
.................................................................................................................................... 1
1.2 G
ENERALITIES
............................................................................................................................................. 1
1.3 M
ANUFACTURER
......................................................................................................................................... 1
1.4 T
ERMS AND CONDITIONS
............................................................................................................................... 1
1.5 M
ANUFACTURER
’
S
L
IABILITY
........................................................................................................................... 1
1.6 A
PPLICABLE
S
TANDARDS AND
D
IRECTIVES
.......................................................................................................... 2
1.6.1 General Standards ........................................................................................................................... 2
1.6.2 European Directives (mandatory only for installations in EU Countries) ............................................ 2
1.7 S
YMBOLOGY
U
SED
....................................................................................................................................... 2
1.7.1 Signs of warning .............................................................................................................................. 2
1.7.2 Signs of obligation ........................................................................................................................... 2
2 DEVICE DESCRIPTION ..................................................................................................................................... 3
2.1 G
ENERAL
D
ESCRIPTION
................................................................................................................................. 3
2.2 I
DENTIFICATION OF THE
M
AIN
P
ART
................................................................................................................. 3
2.3 A
CTUATOR CODING DESCRIPTION
..................................................................................................................... 4
3 TECHNICAL DATA ........................................................................................................................................... 5
4 NAMEPLATE ................................................................................................................................................... 5
5 INSTALLATION ................................................................................................................................................ 6
5.1 T
RANSPORT
................................................................................................................................................ 6
5.2 R
ECEPTION
................................................................................................................................................. 7
5.3 S
TORAGE
................................................................................................................................................... 7
5.4 R
EQUIREMENTS OF
S
TABILITY
......................................................................................................................... 7
5.5 I
NTERFACE DOCUMENT AND DIMENSIONAL DRAWING
............................................................................................ 7
5.6 I
NSTALLATION
............................................................................................................................................. 8
5.6.1 Checks to be performed before installation ...................................................................................... 8
5.6.2 Assembling of the actuator on the valve .......................................................................................... 8
5.6.3 Pneumatic Connections ................................................................................................................... 9
5.6.4 Electrical Connections (If any) ........................................................................................................ 10
5.6.5 Hearting connection ...................................................................................................................... 10
5.7 D
ISASSEMBLING
........................................................................................................................................ 10
6 OPERATION AND USE ................................................................................................................................... 11
6.1 O
PERATION DESCRIPTION
............................................................................................................................. 11
6.2 I
NTENDED USE
.......................................................................................................................................... 11
6.3 R
EASONABLY FORESEEABLE MISUSE
................................................................................................................ 11
6.4 O
PERATING LIMITS
..................................................................................................................................... 12
6.5 R
ESIDUAL
R
ISKS
......................................................................................................................................... 12
7 INSTRUCTIONS FOR THE OPERATOR............................................................................................................. 13
7.1 S
TART
U
P
................................................................................................................................................ 13
7.2 S
TROKE ADJUSTMENT
................................................................................................................................. 13
7.3 M
ECHANICAL MANUAL OVERRIDE
(I
F ANY
) ....................................................................................................... 15
7.4 D
ECLUTCHABLE MECHANICAL MANUAL OVERRIDE
(I
F ANY
) ................................................................................... 16
7.5 P
OSITION OF
M
ECHANICAL MANUAL OVERRIDE
................................................................................................. 16
7.5.1 Double acting version (RTC) ........................................................................................................... 17
7.5.2 Single acting version spring to close (RTCS_CL) ............................................................................... 17
7.5.3 Single acting version spring to open (RTCS_OP) .............................................................................. 17

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Manual 5100, rev. 06 06/2020 – RTC/RTCS
iii
8 MAINTENANCE............................................................................................................................................. 18
8.1 P
ERIODIC
I
NSPECTIONS
................................................................................................................................ 18
8.2 S
PECIAL MAINTENANCE
............................................................................................................................... 19
8.2.1 Seals replacement ......................................................................................................................... 19
8.3 R
EPAIRS
.................................................................................................................................................. 23
8.4 R
EASSEMBLING
......................................................................................................................................... 23
8.4.1 Pneumatic cylinder re-assembling. ................................................................................................. 23
8.4.2 Actuator re-assembling.................................................................................................................. 24
8.5 M
ECHANISM
L
UBRIFICATION
........................................................................................................................ 24
8.5.1 Scotch yoke mechanism (see Paragraph 8.4.2) ............................................................................... 24
8.5.2 Pneumatic cylinder (see Paragraph 8.4.1) ...................................................................................... 24
9 TROUBLESHOOTING ..................................................................................................................................... 25
10 PARTS LIST GENERAL ASSEMBLY .............................................................................................................. 26
11 SPARE PARTS ............................................................................................................................................ 33
11.1 S
PARE PART KIT FOR DOUBLE ACTING ACTUATOR
RTC
SERIES
................................................................................. 33
11.2 S
PARE PART KIT FOR SINGLE ACTING ACTUATOR
RTC
SERIES
.................................................................................. 33
12 DECOMMISSIONING ................................................................................................................................. 34
13 DECLARATION OF INCORPORATION ......................................................................................................... 35

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 1 -
1 GENERAL INFORMATION
1.1 General Warnings
Important This Instruction Manual is an integral part of the machine, it should be carefully
read before carrying out any operation and it should be kept for future
references.
This Instruction Manual covers the RTC Series actuators in the base version
without any accessories and/or control panel.
In case accessories and/or control panel are foreseen mounted on the actuator
an additional Section to this Instruction Manual will be attached to the specific
actuator.
This Instruction Manual is realized in accordance with the Directive 2006/42/CE.
When the actuators are used for safety application with required SIL level (IEC
61508/61511) please refer also to the specific safety manual.
1.2 Generalities
STI S.r.l. actuators are conceived, manufactured and controlled according to the Quality Control System
in compliance with EN ISO 9001 International Standard.
1.3 Manufacturer
With respect to Machinery Directive 2006/42/EC the Manufacturer of the described RTC/RTCS actuator
series, is STI S.r.l. as specified on the machinery label.
STI S.r.l. Via Dei Caravaggi 15
24040 Levate (BG) Italy
Tel. [phone]
Fax [phone]
[e-mail]
1.4 Terms and conditions
STI S.r.l. guarantees each single product to be free from defects and to conform to current goods
specifications. The warranty period is one year from the date of installation by the first user, or eighteen
months from the date of shipment to the first user, whichever occurs first.
The warranty does not cover special products or components not covered by warranty in their turn by
subcontractors. No warranty is given for products which have been subject to improper storage, improper
installation, misuse, or corrosion, or which have been modified or repaired by unauthorised personnel.
Repair work due to improper use will be charged at standard rates.
1.5 Manufacturer’s Liability
STI S.r.l. declines all liability in the event of:
- use of the actuator in contravention of local safety at work legislation
- incorrect installation, disregard or incorrect application of the instructions provided on the actuator
nameplate and in this manual
- modifications without STI’s authorisation
- work done on the unit by unqualified or unsuitable persons.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 2 -
1.6 Applicable Standards and Directives
1.6.1 General Standards
- EN ISO 12100:2010: Safety of machinery - General principles for design.
Risk assessment and risk reduction.
- IEC 61508-1/7 (Ed. 2010)
- IEC 61511-1 (Ed. 2016)
1.6.2 European Directives (mandatory only for installations in EU Countries)
- 2006/42/EC Machinery Directive.
- 2014/68/EU Pressure Equipments Directive (PED)
- 2014/35/EU Directive for Low Voltage Equipment (LV)**
- 2014/30/EU Directive relating to the Electromagnetic Compatibility (EMC)**
- 2014/34/EU Directive concerning equipment for use in potentially explosive atmospheres (ATEX)
** Applicable only when electrical control panel is supplied integrate with the actuator
1.7 Symbology Used
1.7.1 Signs of warning
Be careful where these symbols are shown, they indicate a potentially hazardous situation and they
warn that if the steps are not properly performed, MAY RESULT CAUSING serious injury, death or
long-term risks to the health of exposed persons.
1.7.2 Signs of obligation
General
obligation (with
the possible
supplementary
signboard)
Must wear
protective
clothing.
Obligation to
wear
protective
footwear.
Is required to
wear a helmet.
Is required to
protect the
eyes.
Obligation to
protect your
hearing.
GENERAL DANGER DANGER POWER SUPPLY CRUSHING HAZARD

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 3 -
2 DEVICE DESCRIPTION
2.1 General Description
RTC Single/double acting pneumatic low-pressure actuators, are suitable for the operation of quarter turn
valves (ball valves, butterfly valves, plug valves) for ON-OFF and modulating heavy-duty service
The actuator is made up of a weatherproof scotch yoke mechanism transforming the linear movement of
the pneumatic cylinder (on closing or opening) into the rotary movement, which is necessary for valve
operation.
The travel stroke of the yoke is adjustable between -4 deg / +4 deg at both ends by means of the external
mechanical stops arranged into the side-wall of the mechanism body and into the end flange of the
pneumatic cylinder.
Scotch yoke mechanism centerbody cover is machined to provide the assembly pattern for any required
accessories (i.e. positioner, signaling limit switches, position transducer, etc.) by means of proper
matching units. The above mentioned accessories are operated by the actuator drive sleeve.
Actuator centerbody bottom wall is machined with threaded holes to allow actuator mounting on top of
valve top-work either directly or, when required, with the interposition of an adaptor flange or a mounting
bracket.
2.2 Identification of the Main Part
The RTC actuator is composed by three main parts:
1) Scotch yoke mechanism.
2) Pneumatic cylinder.(with internal spring for single acting version)
3) Stopper screw assembly.
4) Stop setting screw kit
Fig. 1: Main parts for RTC/RTCS actuator series

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 4 -
2.3 Actuator coding description
- - - - - -
V
RTC
RTCS
M
01
02
03
Y
S
C
C
75
100
125
135
160
200
235
255
300
M1
1
2
3
S
A
B
C
D
E
F
G
A
CL
OP
H
HW
H
Accessorie s
Manual Handw heel
canted
Diameter = 255 mm
Diameter = 75 mm
Diameter = 100 mm
Diameter = 125 mm
Diameter = 135 mm
Diameter = 200 mm
Diameter = 235 mm
Diameter = 300 mm
Model 01
Model 02
Model 03
S
Model 01 (MOT=1100 Nm)
Model 02 (MOT=3000 Nm)
Model 03 (MOT=6000 Nm)
Diameter = 160 mm
M Y CV M1
Symmetric
Spring typeC
Spring type D
Spring type E
Spring type F
Spring type G
A
Spring to Close
Spring to Open
Double acting
Single acting
Version
Model
Yoke type
Cylinder diameter
Model (only for RTCS version)
Spring type
Action
Spring type A
Spring type B

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 5 -
3 TECHNICAL DATA
DATA
Supply medium
(1)
Air, Nitrogen or Sweet Gas
Operating temperature
General applications (outside EU Countries):
Standard: -30°C +100°C
Optional: -60°C +100°C (*)
PED applications (within EU Countries):
Standard: -20°C +100°C
Optional: -50°C +100°C (*)
(*) for SIL applications T° amb. min ≥ -40°C
Cylinder design pressure 12 bar
Operating pressure range Data are available on the nameplate (depending on customer
requirements and specifications.)
Max Output torque
RTC 01 Series up to 1100 Nm
RTC 02 Series up to 3000 Nm
RTC 03 Series up to 6000 Nm
Applications On-Off
Modulating service (on request)
(1)
Recommended quality of the medium at the inlet port of pneumatic cylinder according to ISO 8573-1:
- Solid particle Class 7 (particle size ≤ 40 µm, concentration ≤ 10 mg/m3)
- Humidity Class 3 (pressure dew point ≤ -20°C)
- Oil Class 4 (concentration total oil ≤ 5 mg/m3)
Contractor shall specify the quality of the supply medium considering the above recommendation.
4 NAMEPLATE
The identification plate fixed on the actuator contains the main actuator operating conditions.
It is forbidden to modify the information and the marks imprinted in the nameplate without previous written
authorization by STI S.r.l.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 6 -
5 INSTALLATION
5.1 Transport
Important: The lifting and handling should be made by qualified staff and in compliance
with the laws and provisions in force.
Warning: Lift the actuator as shown in Fig.2.
The fastening points are appropriate for the lifting of the actuator alone and not for
the valve + actuator assembly.
Warning: Avoid that during the handling, the actuator passes above the staff.
The actuator should be handled with appropriate lifting means.
The weight is reported on the delivery bill and on overall-dimensions drawings
furnished with the documents accompanying the actuator.
For base actuator dimensions and weights please consult www.stiactuation.com
Fig. 2 – Lifting points for RTC/RTCS actuator series
Important: Not performing the following procedures will invalidate the product guarantee.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 7 -
5.2 Reception
- Check that the model, the serial number of the actuator and the technical data reported on the
identification plate correspond with those of order confirmation (Sect. 4).
- Check that the actuator is equipped with the fittings as provided for by order confirmation.
- Check that the actuator was not damaged during transportation: if necessary renovate the painting
according to the specification reported on the order confirmation.
- If the actuator is received already assembled with the valve, its settings have already been made at
the factory. If the actuator is delivered separately from the valve, it is necessary to check, and, if
required, to adjust, the settings of the mechanical stops (Sect. 6.2).
5.3 Storage
All the actuators RTC leave the factory in perfect condition. Performances of each unit are guaranteed by
individual test and data reported on a specific test certificate issued for each unit.
In order to maintain these characteristics until the RTC actuator is installed on site, proper attention must
be observed for preservation during the storage period.
If the actuator needs storage, before installation follow these steps:
- Place it on a wood surface pallet or on metallic support, so that they are not in direct contact with the
ground
,
in order not to deteriorate the area of valve coupling, later it must be packed with appropriate
covering.
- Make sure that plastic plugs are present on the pneumatic and electrical connections (if present).
- Check that the limit switch box (if any) is properly closed.
If the storage is long-term or outdoor:
- Keep the actuator protected from direct weather conditions.
- Replace plastic plugs of pneumatic and electrical connections (if any) with metal plugs that guarantee
perfect tightness.
- Coat with grease or protection disc, the valve coupling area.
- Coat with grease the screw of the mechanical manual override, if present.
- Periodically operate the actuator (Sect.5).
5.4 Requirements of Stability
- Conditions in which the machinery meets the requirement of stability during use, transportation,
assembly, dismantling when out of service, testing or foreseeable breakdowns, are shown in Fig.2.
- The actuator must be put, with extreme caution, in a right position on a plane surface and with
adapted capacity to the load to support.
- Do not use actuator eye bolts lifting of valve-actuator package.
- Concerning the requirement of stability during installation and disassembling it’s possible to refer to
the next chapters 5.6 and 5.7.
5.5 Interface document and dimensional drawing
- Pneumatic diagrams, wiring diagrams and dimensional drawing are furnished with document
accompanying the actuator.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 8 -
5.6 Installation
Warning: Before proceeding with any Installation the following instructions must be
respected:
- Always wear protective clothing, gloves, and eyewear to prevent personal
injury.
- Use the lifting point foreseen on the actuator to move the actuator: if
different instructions are not well specified the lifting points foreseen on
the actuator must be used only to move the actuator.
- Check with your process or safety engineer for any additional measures
that must be taken to protect against process media.
5.6.1 Checks to be performed before installation
If the RTC actuator is purchased separately, proceed as follows before assembling it onto the valve:
1) Check that the coupling dimensions of the actuator/coupling block flange and stem meet the
specified coupling dimensions.
2) Prepare the necessary tools for the assembly and setting of the unit.
3) Check that the outer surface of the actuator is free from dust and dirt.
4) Clean the actuator flange and remove anything that might prevent a perfect adherence to the
actuator/coupling block flange and joint especially all traces of grease.
5.6.2 Assembling of the actuator on the valve
The actuator can be assembled on top of the valve flange either by using the actuator-housing flange
with threaded holes, or by the interposition of a proper mounting hardware.
The actuator drive sleeve is generally connected to the valve stem by an insert bush or a stem
extension. The assembly position of the actuator, with reference to the valve, must comply with the
plant requirements (cylinder axis parallel or perpendicular to the pipeline axis).
To assemble the actuator onto the valve proceeds as follows:
 Move the valve and the actuator to their fails position
 If an insert bush or stem extension for the
connection to the valve is supplied separately,
assemble it onto the valve stem and fasten it by
tightening the proper stop dowels.
 Connect a sling to the support points of the actuator
and lift it: make sure the sling is suitable for the
actuator weight
 Lower the actuator onto the valve in such a way that
the insert bush, assembled on the valve stem, enters
the actuator drive sleeve. This coupling must take
place without forcing and only with the weight of the
actuator.
 When the insert bush has entered the actuator drive
sleeve, check the holes / pin of the valve flange
meet the actuator holes and pin, otherwise rotate the
mounting bracket to obtain a right assembling.
Fig. 3 – Assembling of the actuator on the valve
2
1
Brachet

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 9 -
Important To guarantee the correct transmission of torque from the actuator to valve stem
without phenomena of slip it is important to:
- remove any trace of oil and/or grease from the mating surfaces of actuator
and bracket (or flange) [1] and from bracket (or flange) and valve flange [2].
- tighten the bolts fixing the bracket (or flange) to the bottom flange of the
actuator with the torque specified into the following Table 1.
tighten the bolts fixing the bracket (or flange) to the bottom flange of the
actuator with the torque specified into the following Table 2, provided that the
valve maker verifies and guarantees the correct transmission of required valve
torque.
Table 1 Table 2
Actuator ISO 5211
flange Bolts Tightening torque (Nm)
(1)
Bolts Tightening
torque (Nm)
(1)
Bolts Tightening torque (Nm)
(1)
RTC/S-01 F12 4 x M12 70 M10 40 M36 1.800
RTC/S-02 F14 4 x M16 180 M12 70 M42 3.000
RTC/S-03 F16 4 x M20 340 M16 180
M20 340
M24 550
(1) The torque values in Tables 1 and 2 have been calculated considering the standard bolting made in
Carbon Steel according to ASTM A320 grade L7/ASTM A193 grade B7 for bolts/screws and ASTM
A194 grade 4 for the nuts. Alternative bolting in Stainless Steel are permitted i.e. ASTM A193 B8M
(Class 2 or 2C) for bolts/screws and ASTM A194 grade 8M for the nuts, provided that yield strength of
bolts/screws is not less than 450 MPa.
5.6.3 Pneumatic Connections
Warning: Check that the values of pneumatic supply available are compatible with those
reported on the identification plate of the actuator.
Warning: Use pipes and connections appropriate as for type, material and dimensions.
Warning: The connection should be made by qualified staff.
- Properly deburr the ends of rigid pipes.
- Properly clean the interior of pipes sending through them plenty of the supply fluid used in the system.
- Mould and fasten the connection pipes so that no irregular strains at entries or loosening of threaded
connections occur.
- Make the connections according to the operating diagram.
-
Check the absence of leakages from pneumatic connections. If necessary, tighten the nuts of the pipe-
fittings.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 10 -
5.6.4 Electrical Connections (If any)
Warning: Use components appropriate as for type, material and dimensions.
Warning: The connections should be made by qualified staff. Before carrying out any
operation, cut line power off.
- Introduce connection cables.
- Make the connections in compliance with applicable wiring diagrams on the documentation supplied.
- Screw the cable gland.
- Replace the plastic plugs of unused entries with metal plugs.
5.6.5 Hearting connection
If the hearting connection is not guaranteed trough mechanical parts where actuator is mounted, it is
necessary ensure a directly hearting connection on provided point of actuator.
5.7 Disassembling
Fig. 4 – Disassembling of the actuator
Warning: Before removing the screws between actuator and valve or adaptor flange or
mounting bracket, the actuator should be connected with appropriate lifting
means. Lift the actuator as shown in Fig.3. The fastening points are
appropriate for the lifting of the actuator alone and not for the valve + actuator
assembly.
During the disassembling take care that mounting coupling block is fix on the
valve stem to avoid any dangerous situation.
Warning: If not already removed disconnect all operating pressure from actuator power
cylinders.
Screws to be removed

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 11 -
6 OPERATION AND USE
6.1 Operation description
The RTC series is pneumatic actuator designed for on-off and control service and is applicable over a
wide range of pressure, temperatures and environments.
The scotch yoke mechanism converts the linear motion of pneumatic piston into valve rotation by the
actuator shaft. The symmetric scotch yoke mechanism generates high torque at start (0° degree) and the
end (90° degree) of the valve stroke, typically valve torque figure of ball valve. The canted scotch yoke
mechanism generates very high torque when valve is closed, typically valve torque figure of butterfly
valve.
For Single acting actuator the spring is located inside the pneumatic cylinder on the piston rod side. The
spring provides the required safety function, the valve either opens or closes if the pneumatic supply is
interrupted
6.2 Intended use
The machinery covered in this Instruction Manual are single and double acting pneumatic low
pressure RTC actuator series designed to operate a quarter turn industrial valve (ball valves,
butterfly valves, plug valves, dampers...) for ON-OFF or modulating heavy duty service.
This RTC actuator Series is produced by STI S.r.l. [Manufacturer] and identified by a label with a product
designation code. STI S.r.l. will not be liable for any possible damage or physical injury resulting from use
in other than the designated applications or by lack of care during installation, operation, adjustment and
maintenance of the machine. Such risks lie entirely with the user. Depending on the specific working
conditions, additional precautions may be requested. Considering that STI S.r.l. has no direct control over
particular applications, operation or maintenance conditions, it is the operator’s responsibility to comply
with all applicable safety rules. Please inform STI S.r.l. urgently if you face unsafe situations not
described in this Instruction Manual. It is the sole responsibility of the operator to ensure that the local
health and safety regulations are adhered to.
RTC actuator Series is designed in accordance with the applicable International Rules and Specifications,
but the following Regulations must be observed in any case:
- the general and safety regulations
- the plant specific regulations and requirements
- the proper use of personal and protective devices (glasses, clothing, gloves, etc)
- the proper use of tools, lifting and transport equipment.
Warning
It is severely forbidden to use the RTC actuators Series for purpose or application
other than those for which it was designed and here above specified.
6.3 Reasonably foreseeable misuse
A short list of reasonably foreseeable misuse:
- Installation in ambient with not planned conditions: i.e. climatic conditions different from the specified
conditions;
- Insert incorrect fluid into the system;
- Supply pressure out of required range;

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 12 -
- Lifting of the actuator with valve through eye bolts.
6.4 Operating limits
Operating conditions are described in paragraph 3, the nameplate fastened on the actuator contains the
main actuator operating condition for the specified application.
Warning
It is severely forbidden to use the actuator under conditions other than those
provided on the nameplate.
6.5 Residual Risks
Warning
The actuator has parts under pressure. Use the due caution.
Use individual protections provided for by the laws and provisions in force.
- Risk due to movements of loads during load displacements, assemblage and maintenance servicing.
- Electrical risk due to an incorrect application of the instruction.
- Crushing during assemblage and maintenance servicing.
- Extreme metal temperature at high (over than 80°C) or very low values as consequence of ambient
temperature as to be considered as a risk of person injury in case of contact.
- Emissions of hazardous substances where natural gas is used as motive energy.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 13 -
7 Instructions for the operator
7.1 Start Up
During the start-up of the actuator, proceed as follows:
- Check that the pressure and quality of the air supply (filtering degree, dehydration) are as prescribed.
- Check that the feed voltage values of the electric components (solenoid valve coils, micro-switches,
pressure switches, etc.) are as prescribed.
- Check that the actuator controls work properly (remote control, local control, emergency controls, etc.)
- Check that the required remote signals (valve position, air pressure, etc.) are correct.
- Check that the setting of the components of the actuator control unit (pressure regulator, pressure
switches, flow control valves, etc.) meet the plant requirements.
- Check that there are not leak in the pneumatic connections. If necessary tighten the nuts of the pipe
fittings.
- Remove all rust and, in accordance with the applicable painting specifications, repair paint-coat that
has been damaged during transport, storage or assembly.
7.2 Stroke adjustment
Important
It is assumed that the following instructions are executed in the workshop
using air as the power fluid.
Instructions are applicable when the actuator is already installed on the valve.
It is important that the mechanical stops of the actuator (and not those of the valve) stop the rotary stroke
at both extreme valve positions (fully open and fully closed), except when different configuration is
required by the type of the valve (i.e,: eccentric butterfly valves,..).
The setting of the open/closed valve position is performed by adjusting the setting screws
foreseen into the end flange of the cylinder and on the side wall of the scotch yoke mechanism
(see Fig. 5 and Fig. 6) following the instructions listed here below.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 14 -
For the adjustment of the travel stop screw in the end flange of the pneumatic cylinder proceed as follows
(Fig.5):
- Loosen the plug (3.4) from the travel stop protection (3.3) keeping the latter locked with a proper
wrench key.
- Adjust the valve stroke screw/unscrew the travel stop screw (3.1)
- After detected the right position, tight the travel stop protection (3.3) against the cylinder end flange
keeping the stopper screw (3.1) locked Screw the plug (3.4) into the travel stop protection (3.3).
For the open position adjustment on the travel stop located into the actuator centerbody side-wall proceed
as follows (Fig.6):
- Loosen the nut (4.1) from the travel stop screw (4.2) keeping the latter locked with a proper wrench
key.
- Adjust the valve stroke screw/unscrew the travel stop screw (4.2)
- After detected the right position, tight the nut (4.1) keeping the travel stop screw (4.2) locked.
Fig. 5 – Stroke adjustment Fig. 6 – Stroke adjustment
Important
Operate the actuator with pneumatic supply to check that the actuator moves
properly and that there are no leakages.

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Manual 5100, rev. 06 06/2020 – RTC/RTCS - 15 -
7.3 Mechanical manual override (If any)
The mechanical manual override is used for the manual operation to open/close the valve, in lack of
supply pressure.
Fig. 7 – Mechanical manual override for double acting version
Fig. 8 – Mechanical manual override for single acting version
Prior to engage mechanical override, pneumatic cylinder shall be depressurized.
 Double acting:
Turn counter-clockwise the hand-wheel (1) in the end flange to open main valve taking care the
handwheel (2) on the centerbody is not engaged and turn clockwise the hand-wheel (2) in the centerbody
flange to close main valve taking care the hand-wheel in the end flanges not engaged.
To restore remote/normal condition turn hand-wheel (1) clockwise against travel stop and turn hand-
wheel (2) counter-clockwise against travel stop.
 Single acting to close:
Turn counter-clockwise the hand-wheel (3) in the end flange to open main valve. To restore the
normal/remote condition turn hand-wheel clockwise against travel stop.
 Single acting to open:
Turn clockwise the hand-wheel (3) in the end flange to close main valve. To restore the normal/remote
condition turn hand-wheel counter-clockwise against travel stop.
.
1
2
3

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STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5100, rev. 06 06/2020 – RTC/RTCS - 16 -
Important
DO NOT APPLY additional force, once against travel stop.
Operate the actuator with pneumatic supply to check that the actuator moves
freely.
Important
After every manual override operation, restore the grease on the mechanical
manual override screw.
See chapter 8.5 for grease specifications.
7.4 Declutchable mechanical manual override (If any)
For manual operation, push down the handle (Fig. 9) and turn the handwheel, following the instruction
described in paragraph 7.3.
Once the operation is done, pull up the handle as before to start.
Fig. 9 – Mechanical manual override for single acting cylinder
7.5 Position of Mechanical manual override
Important Position of the valve in relation to the position of mechanical manual override
MUST be always known.
The following sketches in paragraphs 7.5.1, 7.5.2, 7.5.3, display this
information.
Note: the information on the sketches are valid for the valves that CLOSE
CLOCKWISE.
Handwheel