STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY
www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS
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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:
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the local general and safety regulations
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the plant specific regulations and requirements
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the proper use of personal and protective devices (glasses, clothing, gloves, etc)
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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.
Summary of Contents for RTQ Series
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