Thermoplastic piping systems have gained extraordinary
acceptance in the life science and semiconductor industries over the past
decade. Specifically, PVDF (polyvinylidene fluoride), a flouroplastic, is the
material of choice for high purity water and chemical applications due to its
excellent purity, temperature, surface and strength characteristics.
Other physical properties of PVDF include low weight,
abrasion resistance, and high impact strength. With excellent all-round
chemical resistance and low water absorption, these properties combine to
provide a valve material that meets stringent requirements in a variety of high
purity and chemical applications.
A growing application for both semiconductor and life
science markets is the use of hot Ultra Pure Water (UPW), or hot De-Ionized
Water (DIW). In the past, these systems have operated at 70°F, but due to
benefits of increased chemical reaction times by introducing elevated
temperatures, more and more companies are specifying 180°F (80°C) water
systems. This has been a challenge for thermoplastic piping system
manufacturers.
The melt point of PVDF is 352°F. Therefore, the material
expands as the temperature increases. Successful management of this expansion
is critical to maintaining the integrity of a piping system. Particularly,
diaphragm valves are most susceptible to leakage based on its different
materials of construction, which include a PVDF body, PTFE diaphragm, EPDM
backing diaphragm and polypropylene housing. Each of these thermoplastic
materials has a different melt point and expansion coefficient that must be
accounted for.
To solve this challenge, George Fischer, Inc. designed the
first SYGEF® PVDF High Temperature Resistant (HTR) diaphragm valve. This
valve incorporates secondary sealing components manufactured from high purity
TFM within the valve body to absorb the different expansion characteristics of
the valve materials. The benefit is a high purity diaphragm valve that:
* Meets
the specifications of the SYGEF PVDF system,
* Does
not leak during wide and continuous temperature fluctuations, and
* Maintains
specified pressure ratings along the entire temperature curve.
The HTR series valve is differentiated physically from the
standard temperature valve by its handle. The HTR valve is manufactured with a
red handle compared to the black handle installed on the standard valve. This
differentiation is critical to field personnel for properly identifying and
understanding the capabilities and service characteristics of the product. The
handle also features a snap-on handwheel design for easy removal and
installation and provides an optional locking mechanism.
To support the flexible requirements of engineers,
contractors and end users when installing a piping system, George Fischer has
introduced a diverse HTR diaphragm valve product range offered in sizes from
1?2 in. through 2 in. (20mm - 63mm). Flow can be provided in either
direction irrespective of installation position, offering further system design
flexibility.
All of the new valves offer superior cycle-life and compact
dimensions with the shortest possible branch geometry requiring the least
amount of space for installation. Available in multiple configurations, each is
manufactured to standard or HTR specifications and can be pneumatically
actuated for automated control.
The SYGEF Type 314 valve configuration features patented
high purity union end connectors for easy removal of the product once
installed. The SYGEF Type 315 valve offers multiple fusion end connections from
the popular Infrared (IR) Plus® to the smooth Bead and Crevice Free (BCF)
Plus® fusion technology. These valves can also be customized with NPT,
flange or tube flare end connections.
The Type 319 valve configuration is a single molded
tee/valve assembly that limits the area for bacterial build-up when the branch
valve is closed. The SYGEF Type 319 is designed with no dead area between the
PTFE diaphragm seal and media flow to maintain optimal purity for ultrapure
water applications.
The introduction of the SYGEF HTR diaphragm valve series
provides significant financial benefits of a leak-free valve: low maintenance
and service costs due to reduced system shutdowns. This in turn increases
productivity and product yields.
For more information, phone George Fischer, Inc. at
714-731-8800.
