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A division of Ashcroft Inc., Weksler has set
the standard worldwide for accuracy, quality and dependability.
Weksler manufactures an extensive line of pressure gauges.
Considerations in Selecting a Weksler
Switch
Before selecting a Weksler temperature or pressure
switch, consider the following:
1. Actuator
The actuator responds to changes in pressure,
temperature or differential pressure and operates the switch element
in response to these changes.
The actuator is normally exposed to process fluid
and must therefore be chemically compatible with it. The following
may be used to help select actuator type:
For nominal pressure ranges 0-15 psi through
0-3000 psi, the standard Weksler actuator is a diaphragm-sealed
piston. In this actuator, process pressure acting on the piston area
causes it to overcome the adjustment spring force and actuate a
snap-action switch. A diaphragm and O-ring seal the process media
from this mechanism. These are available in various materials, i.e.:
Buna N, Teflon and Viton. The standard process connection is
stainless steel. Optional monel pressure connection is available.
For H2O pressure and differential pressure ranges,
a diaphragm actuator is used. In this design, the standard pressure
connections are carbon steel. Diaphragms are available in Viton,
Buna N and Teflon. Always review process temperature limits before
making seal selections. Optional stainless steel pressure
connections are available (option XTA).
For high differential pressure ranges, 3-15 to
60-600 psid, a dual diaphragm-sealed piston actuator is used. This
actuator is designed for high static-pressure applications. The
standard pressure connections are nickel-plated brass. Weksler
diaphragms are available in Viton, Buna N and Teflon. Always review
process temperature limits before making seal selections. Optional
stainless steel pressure connections are available (option XUD).
For all temperature ranges, the standard Weksler
temperature actuator operates on the vapor pressure principle: the
vapor pressure in a sealed thermal system is applied to a sensing
element, which in turn actuates a switch. This is known as a
SAMA Class II system. Various filling materials are
used, including propane, butane, methyl alcohol, n-propyl alcohol
and xylene. High overtemperature capability is possible with this
type of system. The interface between liquid and vapor is the point
at which sensing occurs. This is the “sensitive” portion of the
bulb. Weksler bulb extensions and capillary are normally filled with
vapor, and have little effect on the setpoint, regardless of ambient
temperature variations; therefore, no ambient compensation is
required. For best results, the bulb should be mounted within 60
degrees of vertical to assure the liquid remains in the bulb.
2. Enclosure
The enclosure protects the switch element and
mechanism from the environment and has provisions for mounting and
wiring. All Weksler switch enclosures are epoxy-coated aluminum or
stainless steel for maximum corrosion resistance. Choose between
watertight NEMA 4, 4X for most industrial applications and
explosion-proof NEMA 7/9 for most process applications.
Weksler enclosures include watertight cover
gaskets, external mounting holes and one or two 3/4 NPT electrical
conduit holes for ease of installation. Weksler pressure switches
may also be mounted directly to the process by means of the standard
1/4 NPTF or optional 1/2 NPT pressure connection.
Note: When installing Weksler switches, refer to
instruction sheets included with each switch, the National
Electrical Code, and any other local codes or requirements to assure
safety.
3. The Switching Function
Next, consider the switching function. Most
applications for alarm and shutdown are satisfied by single setpoint,
fixed deadband models. For high/low or alarm and shutdown, the dual
setpoint Weksler models may be selected. For pump, compressor, level
and other control applications, an adjustable deadband Weksler model
is often the best choice.
4. The Switch Element
Finally, the electrical switching element must be
compatible with the electrical load being switched. For ease of
selection, all Weksler electrical switching elements are snap
acting, SPDT (single pole-double throw), or 2 (SPDT). Refer to
Weksler catalog pages for switch element choices. Select a switch
element with electrical rating that exceeds the electrical rating of
the device being controlled by the switch. For better reliability
and safety, optional Hermetically Sealed Weksler switching elements
may be specified.
To start, please select a basic type of
Weksler switch
or contact us for help: |
