30 August 2019 http://www.designworldonline.com DESIGN WORLD
resulting internal temperature is what determines the coil’s required
insulation class: Class B (130°C), Class F (155°C) or Class H (180°C).
Exceeding these ratings can cause the coil to open or burn out
prematurely.
Traditional solenoid valves house the coil in a metallic enclosure.
This design, however, causes the air surrounding the coil to act as
an insulator, preventing the heat from dissipating and raising the
valve’s internal temperature. This type of enclosure ages your valve,
reducing its qualified life.
Alternatives to the traditional solenoid valve design can overcome
these thermal shortcomings. Emerson’s Nuclear Qualified (NP-G/H)
2-, 3- and 4-way solenoid valves integrate its RedHat II technology,
which includes a one-piece, epoxy-encapsulated solenoid coil that
improves valve performance and extends the component’s lifecycle.
The epoxy encapsulation serves as the enclosure with the magnetic
frame molded into the coil. With this design, the coils and solenoids
reduce thermal degradation by dissipating heat more effectively
than traditional coils.
Along with reducing heat degradation, the RedHat II solenoid
design also provides longer qualified life. Depending on the
environmental conditions, typical NP series solenoid valves have a
qualified life of 3 to 4 years. With their lower operating temperature,
NP-G/H solenoid valves have a much longer qualified life — up to 8
to 12 years. Designed as an upgraded drop-in replacement, NP- G/H
solenoid valves also facilitate the plant’s EQ acceptance criteria —
minimizing required documentation. Coil replacement is also easy.
Other solenoid valves require substantial disassembly, NP-G/H
valves involve simply removing a high-shock clip and disconnecting
the conduit to replace the coil.
NP-G/H direct-acting and pilot valves can suit the needs of a
variety of nuclear applications, including pilot operators for control
valves, pressurizing and venting cylinders, and the selection and
diversion of instrument air. Additionally, these valves have the same
fluid piping configuration, mounting brackets, EPDM and FKM
elastomers, pressure rating, and flow rating as NP legacy valves.
The NP-G/H series solenoid valves can operate from 0 psi to the
valve’s maximum-rated pressure. Most nuclear applications fall in
the 80–115 psi range, but many NP-G/H valves can work over 115
psi and below 5 psi if necessary. To make replacing current nuclear
valves easier, the NP-G/H series retains the same brass or stainless-
steel bodies and elastomeric and pressure vessel components as
previous NP models. Many materials, including the elastomers, are
designed to meet the harsh degradation effects found in nuclear
applications. For example, EPDM rubber withstands high radiation
levels, while Viton withstands lower radiation levels but higher
temperatures.
These valves are also 100% inspected and functionally tested
before shipment. DWASCO | http://www.asco.comDESIGN WORLD August 2019 31WHITTET-HIGGINS manufactures quality oriented, stocks
abundantly and delivers quickly the best quality and largest array of
adjustable, heavy thrust bearing, and torque load carrying retaining
devices for bearing, power transmission and other industrial assemblies;
and specialized tools for their careful assembly.
Visit our website–whittet-higgins.com–to peruse the many possibilities
to improve your assemblies. Much technical detail delineated as well as
2D and 3D CAD models for engineering assistance. Call your local
or a good distributor.33 Higginson Avenue, Central Falls, Rhode Island 02863
Telephone: (401) 728-0700 • FAX: (401) 728-0703
E-mail: [email protected] Web: http://www.whittet-higgins.comPOWER TRANSMISSION
RETAINING DEVICES &
maintenance & assembly tools
WHITTET-HIGGINSUSABEARLOK SHOELOK BEARLOK Shrink DiscBEARHUG CLAMPNUT TANGENTLOKPRECISION NUTS & WASHERS ADAPTER SLEEVE ASSEMBLIESNUTS & WASHERS HARDENED TONGUE WASHERS SPLIT COLLARRETHREADING DIES ADJUSTABLE SPANNER WRENCH BEARING ASSEMBLY SOCKETINCH and METRIC THREADS
LEFT HANDED as well as
RIGHT -HANDED
Materials of:
CARBON, ALLOY and
HARDENED ALLOY
STEELS
Materials of:
ALLUMINUM and
CORROSION RESISTANT
STEELDesign Notes 8-19_Vs3.LL.indd 31 8/5/19 10:59 AM