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:
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Check that the pressure and quality of the air supply (filtering degree, dehydration) are as prescribed.
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Check that the feed voltage values of the electric components (solenoid valve coils, micro-switches, pressure
switches, etc.) are as prescribed.
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Check that the actuator controls work properly (remote control, local control, emergency controls, etc.)
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Check that the required remote signals (valve position, air pressure, etc.) are correct.
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Check that the setting of the components of the actuator control unit (pressure regulator, pressure switches,
flow control valves, etc.) meet the plant requirements.
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Check that there are not leak in the pneumatic connections. If necessary, tighten the nuts of the pipe fittings.
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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.
