ties are included. Valving controls
pressure to the actuator with no continuous air bleed (Figures 9 and 10).
Accessory-External-Modulating-Remote (AEMR): While mounted to
the actuator in a manner similar to
AEDRs, AEMRs employ digital
“smart” positioner technology to sense
actuator motion and to provide the
appropriate supply pressure to cause
the desired PST actuator travel.
AEMRs provide continual feedback
regarding valve and actuator motion
along with diagnostic data, and they
accept either remote or local PST activation. Suppliers point out that
AEMRs (as with some MEMLs,
MIARs and AEDRs) are able to perform the PST automatically with no
operator intervention. Signature testing is a normal feature allowing the
identification of failing valves before
they become unavailable as well as
automatic documentation of emergency events. AEMRs remain able to
In selecting the
Figure 11 – A position- proper PSTD to
based AEMR mounted employ, users
directly to the ESD valve must determine
actuator the answer to a
number of questions: Is the relative
simplicity of a manually engaged PSTD
desired, or is an accessory-based PSTD
more applicable with its expanded
diagnostics capabilities? Is a hard stop
preferred, or will sensor-controlled
travel limits do the job—or should
there be a combination of both sensor
and hard stop? Is emergency response
during PST important and is redundancy of components or a relative minimal
number of components a better choice?
How frequently will the PST be activated? Which supplier can provide
respond to an
during the PST
The author appreciates the assistance of the
following companies, which provided information for this article:
ASCO ( www.ascovalve.com)
Dyna Torque ( www.dynatorque.com)
Emerson Process Management-Fisher
Morin ( www.morinact.com)
QTRCO ( www.qtrco.com)
Topworx ( www.topworx.com)
superior support in your quest to satisfactorily achieve a mandated safety
The user is left to determine what is
important for each application, knowing
that each type of PSTD will add significantly to plant safety while helping to
keep process and revenue flowing. VM
ED HOLTGRAVER is CEO of QTRCO, Inc., located
in Tomball, TX. He is a member of the Valve Manufacturers Association Education & Training Committee and the Valve Magazine Editorial Board.
Reach him at firstname.lastname@example.org.
The EIM TEC2000 valve actuators at
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The secret to this speed is the actuator’s
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Specify TEC2000 for your next facility.
Because simple setup means faster setup.
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13840 Pike Road, Missouri City, TX 77489
The EIM TEC2000 valve actuators in this jet-fueling facility at Atlanta’s international airport were
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Visit www.eim-co.com to learn more
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