ABB RS85 Operating Instructions Manual
—
ABB MEASUREMENT & ANALYTICS | OPERATING INSTRUCTION | OI/RS85– EN REV. K
RS85
Vibrating fork level switch
K–TEK Level products
Measurement made easy
Introduction
This operating instruction manual provides the
following information:
• installation
• setup
• time delay
• troubleshooting
2
RS85 VIBRATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
Contents
1 Description .................................3
2 Installation .................................5
3 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Time delay .................................13
5 Troubleshooting........................... 14
6 Warranty statement ........................15
7 ABB RMA form ..............................16
RS85 VIBRATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
1 Description
3
Introduction
The RS85 switch is a vibrating fork switch designed for liquid
level detection. The robust sensor design and built–in
temperature compensation ensure reliable response even in
the presence of very extreme process conditions. The LED
indicators of the RS85 modular electronics allow for simple
set–up and status detection. Configuration is via
pushbuttons or a provided magnet. The rugged construction
allows it to withstand the rigors of just about any industrial
environment.
Theory of operation
The RS85 vibrating switch utilizes a piezoelectric driven
tuning fork that exhibits a change in resonant frequency
when the forks are immersed in any liquid. 'Smart'
microprocessor–based electronics keep the sensor in a
resonant state as it changes from dry to wet or wet to dry.
The resonant frequency is continuously monitored for
changes created by a wet or dry sensor and an alarm (change
in LED) is provided along with a DPDT relay. An important
feature of this device is that its resonant frequency is not
significantly affected by coating on the fork unless the space
between the forks is bridged. The RS85 ability to identify true
liquid level in viscous, coating or aerated liquid is
unparalleled. The self–test option continuously checks for
fault conditions such as a damaged sensor and under fault
conditions displays a blinking red LED visible through the
glass cover. Applications include high/low liquid level
detection and are unaffected by parameters such as specific
gravity, dielectric constant or mounting position of the
sensor.
Dimensions
111 mm
19.05 mm (¾ in)
FNPT
cable entry
279 mm (11 in)
Standard
19.05 mm (¾ in)
MNPT standard
Standard
86 mm
PL*
*Trip point 19.05 mm (¾ in)
from end of probe type
Figure 1
Specification
For detailed specifications consult the RS85 data sheet (DS/
RS85–EN).
4
RS85 VIBRATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
... 1 Description
Sample applications
The RS85 can be used for level detection in tanks, vessels or
piping containing all types of hot or cold liquids and is
suitable for high/low level detection applications in
hazardous areas. The RS85 can be mounted in any
orientation. In vertical applications where room allows, the
unit can be extended into the vessel (up to 84 in) with an
extension tube. The RS85 is also available with Teflon
coatings or alloy wetted parts for use in corrosive fluid and
sticky applications.
RS85
switches
mounted in
external
chamber
Figure 4
RS85 dual compartment
housing and custom
insertion length
RS85
switches
mounted in KM26
magnetic level
gauge
.
.
.
.
2
.
.
Figure 2
Figure 3
Empty pipe detection, level in
vertical pipe
(not to be used as a flow
switch) maximum velocity
.5FPS
Figure 5
RS85 VIBRATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
2 Installation
Mounting
After unpacking the unit, inspect it for any evidence of
shipping damage. Inspect the fork tines to insure that they
are not bent. Forks should be parallel to each other. Any
claims for damage due to shipping must be filed with the
carrier who handled the package (s).
• Select a mounting location for the switch and the sensor
probe. Your unit may be an integral mounting option or the
remote mounting option. The integral mounting unit
consists of a single enclosure that includes the electronic
module and the sensor probe. The remote mounting unit
consists of two enclosures, one containing the electronic
module and the other containing the sensor probe.
• Be sure that there is sufficient clearance around the
mounting position to allow for the turning radius of the
switch or remote sensor enclosure as the unit is screwed
into place. Allow sufficient room above the vessel entry to
be able to insert the probe into the opening of the vessel.
• The standard size of the threaded vessel coupling is ¾ in
NPT for most probes. Other size threaded connections or
flanges are also available.
• Install and tighten threaded process connection switches
with a spanner wrench on the wrench flats of the threaded
connection.
5
Switch point
Top mounted
Figure 6
RS85 mounted via
¾ in NPT
connector
NOTE
Do not rotate switch housing on process connection.
Switch performance may be affected.
• The information included on the enclosure label should be
visible. If necessary clean the label using a cloth soaked
with either water or isopropyl alcohol.
Tank mounting
The RS85 can be mounted for high or low level detection using
a flange or the standard ¾ in NPT connection.
Switch point and mounting position
Switch points on the sensor depend on the mounting
position. The switch point is determined by the position of
the tuning fork.
Figure 7
Switch point
Bottom mounted
Figure 8
Switch Point
Figure 9
Side mounted
6
RS85 VIBRATING FORK LEVEL SWITCH | OI/RS85-EN REV. K
2 ...Installation
Mounting for vessel wall build–up
If there is a potential for build–up on the vessel wall, mount
the RS85 with sufficient distance between the wall and the
fork assembly to prevent bridging.
*
Vertical top mounted
Figure 10
*Ensure that there is sufficient distance between the build–up
expected on the tank and the forks.
Extended into vessel,
side mounted
*
Extended Probe Lengths (PL)
The sensor length 'PL' for the RS85 will differ based on the
process connection. A threaded sensor PL is measured from
the bottom process thread to the tip of the fork tine. A
flanged sensor PL is measured from the face of the flange to
the tip of the fork tine.
Mounting position with extension tubes
If ordering the RS85 with an extended probe length, ensure
there is adequate space between outside walls or ceilings and
the vessel mounting point
A short extended probe length (up to 20 in) can be mounted
in any orientation. An RS85 with an extended probe length
over 20 in (up to 84 in) must be mounted vertically.
Figure 12
Figure 11
19.05 and 25.4 mm
(¾ In and 1 in)threaded
21.5 mm
(0.8500 in) dia.
From lower edge of thread
Flange connection
21.5 mm
(0.8500 in) dia.
Figure 13
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