STI RTQ Series User manual

Quarter turn pneumatic actuator
RTQ Series
Single acting version type RTQS
INSTRUCTION MANUAL 5300

STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS i
Date Rev. Description Author Approved
18/06/2020 9 Revised Nameplate (Section 4.2) G. Alfieri A. Negri
18/07/2019 8
Revised to comply with Shell DEP
32.36.01.18-Gen (Ed.2018)
G. Alfieri F. Tondolo
24/10/2018 7 Revised §1.6 / §2.3 / §8.4 / Section 13 G. Alfieri F. Tondolo
10/01/2017 6 Revised §1.6/added §7.3 M. Bozzarelli F. Tondolo
15/02/2016 5 Revision M. Bozzarelli D. Lamoure
22/09/2015 4 Revision M. Bozzarelli D. Lamoure
11/09/2013 3 Revision G. Alfieri D. Lamoure
31/05/2013 2 Revision D .Lamoure F. Tondolo
26/02/2013 1 Revision P.G.A.Engineering D. Lamoure
31/10/2012 0 Issue P.G.A.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 5300, rev. 09 06/2020 – RTQS 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
1.7 S
YMBOLOGY
U
SED
....................................................................................................................................... 2
2 DEVICE DESCRIPTION ..................................................................................................................................... 3
2.1 G
ENERAL
D
ESCRIPTION
................................................................................................................................. 3
2.2 I
DENTIFICATION OF THE
M
AIN
P
ARTS
................................................................................................................ 3
2.3 A
CTUATOR CODING DESCRIPTION
..................................................................................................................... 4
3 TECHNICAL DATA ........................................................................................................................................... 5
4 IDENTIFICATION NAMEPLATES ....................................................................................................................... 6
4.1 N
AMEPLATE BASED ON
ISO 12490 ................................................................................................................. 6
4.2 S
TANDARD
N
AMEPLATE
................................................................................................................................ 6
5 RECEPTION ..................................................................................................................................................... 7
5.1 L
IFTING AND
H
ANDLING
................................................................................................................................ 7
5.2 C
HECK AT THE RECEPTION
.............................................................................................................................. 8
5.3 S
TORAGE
................................................................................................................................................... 9
5.4 R
EQUIREMENTS OF
S
TABILITY
......................................................................................................................... 9
5.5 I
NTERFACE DOCUMENT AND DIMENSIONAL DRAWING
............................................................................................ 9
6 INSTALLATION .............................................................................................................................................. 10
6.1 C
HECKS TO BE PERFORMED BEFORE INSTALLATION
.............................................................................................. 10
6.2 A
SSEMBLING OF THE ACTUATOR ON THE VALVE
.................................................................................................. 10
6.3 P
NEUMATIC
C
ONNECTIONS
.......................................................................................................................... 12
6.4 E
LECTRICAL
C
ONNECTIONS
(I
F ANY
) ................................................................................................................ 12
6.5 E
ARTH CONNECTION
................................................................................................................................... 12
7 OPERATION AND USE ................................................................................................................................... 13
7.1 O
PERATION DESCRIPTION
............................................................................................................................. 13
7.2 I
NTENDED USE
.......................................................................................................................................... 13
7.3 R
EASONABLY FORESEEABLE MISUSE
................................................................................................................ 14
7.4 O
PERATING LIMITS
..................................................................................................................................... 14
7.5 R
ESIDUAL
R
ISKS
......................................................................................................................................... 14
8 INSTRUCTIONS FOR THE OPERATOR............................................................................................................. 15
8.1 S
TART
U
P
................................................................................................................................................ 15
8.2 S
TROKE ADJUSTMENT
................................................................................................................................. 15
8.3 M
ANUAL
O
VERRIDE
................................................................................................................................... 18
9 MAINTENANCE............................................................................................................................................. 20
9.1 S
ERVICE LIMIT
........................................................................................................................................... 20
9.2 P
ERIODIC
I
NSPECTIONS
................................................................................................................................ 20
9.3 S PECIAL MAINTENANCE ............................................................................................................................... 21
9.4 R
EPAIRS
.................................................................................................................................................. 27
10 ACTUATOR LUBRICATION ......................................................................................................................... 28

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Manual 5300, rev. 09 06/2020 – RTQS iii
10.1 S
COTCH YOKE MECHANISM
(
SEE
P
ARAGRAPH
12.1) ........................................................................................... 28
10.2 P NEUMATIC CYLINDER ( SEE P ARAGRAPH 12.2) ................................................................................................. 28
11 TROUBLESHOOTING ................................................................................................................................. 29
12 GENERAL ASSEMBLIES AND PARTS LIST .................................................................................................... 30
12.1 S
COTCH YOKE MECHANISM
........................................................................................................................... 30
12.2 P
NEUMATIC CYLINDER
................................................................................................................................. 31
12.3 S
TOPPER ASSEMBLY FOR PNEUMATIC CYLINDER
................................................................................................. 32
12.4 S
PRING SINGLE PACKAGE CARTRIDGE
............................................................................................................... 33
12.5 S
PRING DOUBLE PACKAGE CARTRIDGE
............................................................................................................. 34
12.6 S
TOPPER ASSEMBLY FOR SPRING CARTRIDGE
..................................................................................................... 35
13 SPARE PARTS KIT ...................................................................................................................................... 35
14 DECOMMISSIONING ................................................................................................................................. 36
14.1 G
ENERAL INFORMATION
.............................................................................................................................. 36
14.2 R
ECYCLING AND DISPOSAL
............................................................................................................................ 36
14.3 S
PRING CARTRIDGE DEMOLITION
.................................................................................................................... 37
15 DECLARATION OF INCORPORATION ......................................................................................................... 38

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Manual 5300, rev. 09 06/2020 – RTQS 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 RTQS 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 RTQS actuator series, is STI
S.r.l. as specified on the machinery nameplate.
STI S.r.l. Via Dei Caravaggi 15
24040 Levate (BG) Italy
Tel. [phone]
Fax [phone]
imisti.sale[email protected]m
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 5300, rev. 09 06/2020 – RTQS 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 Sings of obbligation
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 5300, rev. 09 06/2020 – RTQS 3
2 DEVICE DESCRIPTION
2.1 General Description
RTQS Single 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) or the linear movement due to the force of an integrated spring (on
opposite direction to the pneumatic cylinder) into the rotary movement, which is necessary for valve operation.
The travel stroke of the yoke is adjustable between ± 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.
The cover of the centerbody of the scotch yoke mechanism is machined to provide the assembly pattern for any
required accessories (i.e. positioner, signalling 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 Parts
The RTQS actuator is composed by six main parts identified in the attached Fig. 1:
1) Scotch yoke mechanism.
2) Pneumatic cylinder
3) Spring cartridge.
4) Stopper screw assembly.
5) Seal Kit.
6) Position Indicator.
Fig. 1: Main parts for RTQS actuator series (Spring to Close configuration)

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Manual 5300, rev. 09 06/2020 – RTQS 4
2.3 Actuator coding description
- - - -
V
RTQS
M
01 05
02 06
03 07
04 08
Y
S
C
C
235 685
255 735
300 785
335 835
385 935
435 1000
485 1100
535 1200
585 1300
635
R
A E
B F
C G
D H
S
1
2
3
4
F
CL
OP
H
HW
HWR
HP
Manual handwheel
Manual handwheel with reduction
Fail direction
Fail to Close
Fail to Open
Spring Size 2
Spring Size 1
Spring Size 3
Spring Size 4
F
Model 01
Model 02
Model 03
Model 04
Model 05
Model 06
Model 07
Model 08
V
Model
Diameter = 535 mm
Diameter = 585 mm
Spring pack model
Diameter = 300 mm
Diameter = 335 mm
Diameter = 385 mm
Diameter = 435 mm
Diameter = 485 mm Diameter = 1100 mm
Diameter = 1200 mm
Diameter = 1300 mm
Diameter = 935 mm
Diameter = 1000 mm
RCM Y
-
Model 01
Diameter = 735 mm
Diameter =785 mm
Diameter = 835 mm
Model 02
Model 03
Model 04
Yoke type
Canted
Symmetric
Diameter = 255 mm
Cylinder diameter
Diameter = 235 mm Diameter = 685 mm
H
Manual overrides
Hydraulic hand pump
S
Spring size
Diameter = 635 mm
Version
Single acting
Model 05
Model 06
Model 07
Model 08

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Manual 5300, rev. 09 06/2020 – RTQS 5
3 TECHNICAL DATA
DATA
Supply medium (1) Air, Nitrogen or Sweet Gas
Operating temperature ranges
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 12,00 bar
Operating pressure values Data are available on actuator nameplate depending
on customer requirements and specifications.
Rated torque per Model
RTQS 01 Series up to 12.000 Nm
RTQS 02 Series up to 22.000 Nm
RTQS 03 Series up to 40.000 Nm
RTQS 04 Series up to 70.000 Nm
RTQS 05 Series up to 125.000 Nm
RTQS 06 Series up to 220.000 Nm
RTQS 07 Series up to 400.000 Nm
RTQS 08 Series up to 600.000 Nm
Design life 30 years
Applications On-Off
Modulating service (on request)
(1) Recommended quality of air at the inlet port of pneumatic cylinder according to ISO 8573-1 (Ed. 2010):
- 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.

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Manual 5300, rev. 09 06/2020 – RTQS 6
4 IDENTIFICATION NAMEPLATES
The identification nameplate 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.
4.1 Nameplate based on ISO 12490
Fig. 2a: ISO 12490 Nameplate
Compilation key:
(1) pressure which generate the maximum rated torque in static conditions at the limits of the yoke which can
be considered coincident with the design pressure used for the design of the pressure containing parts;
(2) pressure which generate the maximum operating torque along all the stroke in dynamic conditions;
(3) minimum pressure in the cylinder available from the supply line or set pressure available at the output of the
pressure regulator (if any).
4.2 Standard Nameplate
A simplified standard nameplate can be used for general purpose application when Customer specific
requirements are not to be fulfilled.
Fig. 2b: Standard Nameplate

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Manual 5300, rev. 09 06/2020 – RTQS 7
5 RECEPTION
5.1 Lifting and Handling
Warning
The lifting and handling must be made by qualified staff and in compliance with the laws
and provisions in force.
Depending on the installation position, lift the actuator as shown in Figures 3a or 3b taking
care that the maximum opening angle between the chains remains below 90°.
The lifting points are appropriate for the lifting of the actuator alone and not for the valve +
actuator assembly.
Avoid that during the handling, the actuator passes above the staff.
The actuator should be handled with appropriate lifting means considering the mass of
actuator.
The mass is reported on the delivery bill and on the overall-dimensions drawings
furnished with the documents accompanying the actuator.
In case the information regarding the mass is missing consult www.imi-critical.com for
base actuators or ask this information at [e-mail].
Fig. 3a – Lifting points of RTQS actuator series for lifting with vertical stem condition
Important
Not performing the following procedures will invalidate the product guarantee.
90° max

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Manual 5300, rev. 09 06/2020 – RTQS 8
Fig. 3b – Lifting points of RTQS actuator series for lifting with horizontal stem condition
5.2 Check at the reception
- Check that the model, the serial number of the actuator and the technical data reported on the identification
nameplate 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 perform the setting after the
assembling on the valve according to the next paragraph 8.2.

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Manual 5300, rev. 09 06/2020 – RTQS 9
5.3 Storage
All the actuators RTQS 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 RTQS 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 or ambient conditions using suitable means.
- If the entries should remain exposed to the ambient, replace plastic plugs of pneumatic and electrical
connections (if any) with metal plugs that guarantee perfect tightness.
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.3a and 3b.
- 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.
Warning
Do not use the eye bolts of the actuator for lifting the valve-actuator package.
5.5 Interface document and dimensional drawing
Pneumatic diagrams, wiring diagrams, dimensional drawing, instruction manual and safety manual (when
request) are furnished with document accompanying the actuator.

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Manual 5300, rev. 09 06/2020 – RTQS 10
6 Installation
Warning It is assumed that the installation, setting, commissioning, are carried out by qualified
personnel and checked by responsible Specialists.
Same instructions apply both for installation of the actuator on the valve in the workshop
and in the field.
Warning Before proceeding with installation, the following instructions must be respected:
- use always wear protective gloves, footwears, clothing, high visibility jacket, eyewear
and any other protective device prescribed by the Local Rules depending on the
working conditions;
- 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 supervisor or Plant Safety Responsible for any additional measures
that must be taken to protect against process media.
6.1 Checks to be performed before installation
If the RTQS actuator is purchased separately, proceed as follows before assembling it onto the valve:
- Check that the coupling dimensions of the actuator/coupling block flange and stem meet the specified coupling
dimensions.
- Prepare the necessary tools for the assembly and setting of the unit.
- Check that the outer surface of the actuator is free from dust and dirt.
- 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.
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.

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Manual 5300, rev. 09 06/2020 – RTQS 11
Fig. 4 – Assembling of the actuator on the valve
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)
RTQS-01 F25 8 x M16 180 M10 40 M36 1.800
RTQS-02 F30 8 x M20 340 M12 70 M42 3.000
RTQS-03 F35 8 x M30 800 M16 180
RTQS-04 F40 8 x M36 1.800 M20 340
RTQS-05 F48 12 x M36 1.800 M24 550
RTQS-06 F60 20 x M36 1.800 M27 700
RTQS-07 F60 20 x M36 2.200 M30 800
RTQS-08 F80 20 x M42 3.000 M33 1.200
(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.
Bottom flange of the actuator [1]
Connection with the valve [2]
Bracket (or flange)

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Manual 5300, rev. 09 06/2020 – RTQS 12
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.
Use pipes and connections appropriate as for type, rating, material and dimensions.
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.
6.4 Electrical Connections (If any)
Warning
Before carrying out electrical connections, switch off any power and control lines.
Use components appropriate as for type, material and dimensions.
The connections should be made by qualified staff.
- 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.
6.5 Earth connection
If the earth connection is not guaranteed trough mechanical parts on which the actuator is mounted, it is
necessary ensure a directly earth connection using the provided heart point of the actuator.

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Manual 5300, rev. 09 06/2020 – RTQS 13
7 OPERATION AND USE
7.1 Operation description
The RTQS is a 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 or spring 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 RTQS the spring cartridge is mounted on the housing wall opposite to the cylinder.
The spring provides the required safety function, the valve either opens or closes if the pneumatic supply is
interrupted Safe spring design ensures proper functionality and safe maintenance, preventing any accidental
hazards due corrosion of bolting.
7.2 Intended use
The machinery covered in this Instruction Manual is single acting pneumatic low pressure RTQS 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 RTQS actuator is produced by STI srl [Manufacturer] and identified by a nameplate with a product designation
code. STI srl 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 srl has no direct control over particular applications, operation or maintenance conditions, it
is the operator’s responsibility to comply with all applicable safety rules.
STI srl must be informed urgently if unsafe situations not described in this Instruction Manual are found in order
the operations of the actuator. It is the sole responsibility of the operator to ensure that the local health and safety
regulations are adhered to.
RTQS actuator is designed in accordance with the applicable International Rules and Specifications, but the
following Regulations must be observed in any case:
- the local 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 strictly forbidden to use the RTQS actuators series for purpose or application
other than those for which it was designed and as specified in this Manual.

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Manual 5300, rev. 09 06/2020 – RTQS 14
7.3 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;
- Lifting of the actuator with valve through the actuator eye bolts.
7.4 Operating limits
The general operating conditions are described in Section 3, the nameplate fastened on the actuator contains the
main actuator operating condition for the specified application.
Warning
It is strictly forbidden to use the actuator under conditions other than those
provided on the nameplate.
7.5 Residual Risks
Warning
The actuator contains springs under load and can have pressurized parts both
during operation and at rest; use the due precautions.
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.
- Critical 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.

STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS 15
8 Instructions for the operator
8.1 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.
8.2 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 flanges of the cylinder and spring cartridge (see Fig. 5 and 6 for spring to Close version and Fig.
7 and 8 for spring to Open version) following the instructions listed on the next paragraphs 8.2.1 and 8.2.2.
8.2.1 Spring to Close version
8.2.1.1 Setting of the stopper on the cylinder side (Fig. 5)
Start this operation with the air in the pneumatic cylinder exhausted and valve in closed or intermediate position.
Loosen the nut (5.3) from the setting screw (5.2) and unscrew the setting screw (5.2) until it remains only a few
threads engaged on the end flange of the cylinder.
By pressurizing the cylinder or by using the manual override, move the valve until it reach the correct setting in
open position. Fix then the valve position by screwing the setting screw (5.2) until it stops on the end part of the
internal piston.
Taking care not to damage it, reinstall the sealing washer (5.4) and screw until it blocks against the surface of the
end flange; put then in place the protection washer (5.1) around the sealing washer (5.4) and block all the system
with the nut (5.3).
To avoid the risk of unsetting the setting screw (5.2) during this last operation, keep the setting screw (5.2) blocked
by using an Allen wrench engaged on the on the hexagonal receptacle.

STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS 16
8.2.1.2 Setting of the stopper on the spring side (Fig. 6)
Start this operation with valve in open or intermediate position.
Loosen the nut (6.3) from the setting screw (6.2) and unscrew the setting screw (6.2) until it remains only a few
threads engaged on the end flange of the spring cartridge.
By releasing the air in the cylinder or by using the manual override, move the valve until it reach the correct setting
in closed position. Fix then the valve position by screwing the setting screw (6.2) until it stops on the end part of
the internal spring stem.
Taking care not to damage it, reinstall the sealing washer (6.4) and screw until it fit into the groove of the spring
cartridge bushing (6.1), then block all the system with the nut (6.3).
To avoid the risk of unsetting the setting screw (6.2) during this last operation, keep the setting screw (6.2) blocked
by using an Allen wrench engaged on the on the hexagonal receptacle.
Fig. 5 – Stroke adjustment detail Fig. 6 – Stroke adjustment detail
8.2.2 Spring to Open version
8.2.2.1 Setting of the stopper on the cylinder side (Fig. 7)
Start this operation with the air in the pneumatic cylinder exhausted and valve in open or intermediate position.
Loosen the nut (7.3) from the setting screw (7.2) and unscrew the setting screw (7.2) until it remains only a few
threads engaged on the end flange of the cylinder.
By pressurizing the cylinder, move the valve until it reach the correct setting in closed position; fix then the valve
position by screwing the setting screw (7.2) until it stops on the end part of the internal piston.
Taking care not to damage it, reinstall the sealing washer (7.4) and screw until it blocks against the surface of the
end flange; put then in place the protection washer (7.1) around the sealing washer (7.4) and block all the system
with the nut (7.3).
To avoid the risk of unsetting the setting screw (7.2) during this last operation, keep the setting screw (7.2) blocked
by using an Allen wrench engaged on the on the hexagonal receptacle.
8.2.2.2 Setting of the stopper on the spring side (Fig. 8)
Start this operation with valve in closed or intermediate position.
Loosen the nut (8.3) from the setting screw (8.2) and unscrew the setting screw (8.2) until it remains only a few
threads engaged on the end flange of the spring cartridge.
By releasing the air in the cylinder, move the valve until it reach the correct setting in open position. Fix then the
valve position by screwing the setting screw (8.2) until it stops on the end part of the internal spring stem.
Taking care not to damage it, reinstall the sealing washer (8.4) and screw until it fit into the groove of the spring
cartridge bushing (8.1), then block all the system with the nut (8.3).