BABBITT LS7500 User manual

LS7500 Presence/Absence Switch
OWNERS MANUAL
♦INSTALLATION
♦CALIBRATION
♦TROUBLESHOOTING
♦WARRANTY
P.O. Box 70094
Houston, TX 77270
[phone]

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This manual contains important information necessary for the proper operation of this product. Before installing the
unit, please read these instructions and familiarize yourself with the requirements and functions of this device.
Any use or distribution of this document without express consent of Babbitt International, Inc. is prohibited. Any
reproduction is prohibited without written permission.
In no event will Babbitt International, Inc. be liable for any mistake, including lost profits, lost savings, environmental
compliance cost or other incidental or consequential damages or injury arising out of the use or inability to use this
manual. Terms and conditions found on our website at www.babbittinternational.com contain additional liability
limitations related to this product.
If any questions or problems arise during installation, please contact
Customer Service: 1-800-835-8012 or 713-467-4438 (8:00 a.m. to 5:00 p.m. CST US)
Failure to follow safe installation and servicing guidelines could result in death or serious injury.
Make sure only qualified personnel perform the installation.
Use the equipment only as specified in this manual. Failure to do so may impair the protection provided by the
equipment.
Do not perform any services other than those contained in this manual unless you are qualified.
Verify the operating environment of the Babbitt LS7500 is consistent with the appropriate area classification.
Improper use or installation of this device may cause the following:
Personal injury or harm.
Application hazards such as pump run dry and/or burnt pumps.
Damage to the device or system.
High voltage that may be present on leads could cause electrical shock.
Make sure the main power to the Babbitt LS7500 presence/absence switch is off and the lines to any other
external power source are disconnected or not powered while wiring the instrument.
WARNING
NOTICE

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Table of Contents
1. DESCRIPTION........................................................................................................................................................... 4
1.1 General Description................................................................................................................................................. 4
1.2 Specifications........................................................................................................................................................... 4
1.3 Ordering Information .............................................................................................................................................. 5
1.4 GA Drawing.............................................................................................................................................................. 6
1.5 Sensor Rings ............................................................................................................................................................ 6
2. THEORY OF OPERATION...................................................................................................................................... 7
3. INSTALLATION ........................................................................................................................................................ 7
3.1 Inspection ................................................................................................................................................................ 7
3.2 Bench Test ............................................................................................................................................................... 7
3.3 Mounting................................................................................................................................................................. 7
3.3.1 Partial-ring Flange Location....................................................................................................................... 7
3.3.2 Full-ring Flange Location ........................................................................................................................... 8
3.3.3 Full-faced Gaskets & Flanges..................................................................................................................... 8
3.4 Physical Installation............................................................................................................................................... 10
3.5 Grounding.............................................................................................................................................................. 10
3.6 Ground Continuity Test ......................................................................................................................................... 10
3.7 Removing the Electronics ...................................................................................................................................... 11
3.8 Typical Applications and Wiring Diagrams ............................................................................................................ 12
4. CALIBRATION........................................................................................................................................................ 16
4.1 Sensitivity Calibration –Conductive Materials...................................................................................................... 16
4.2 Sensitivity Calibration –Non-Conductive Materials.............................................................................................. 17
4.3 Time Delay............................................................................................................................................................. 18
4.4 Setting the Time Delay .......................................................................................................................................... 18
4.5 Fail Safe Selection.................................................................................................................................................. 18
5.MAINTENANCE AND TROUBLESHOOTING ................................................................................................... 19
6. WARRANTY............................................................................................................................................................. 20

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LS7500 PRESENCE/ABSENSE SWITCH
1. DESCRIPTION
1.1 General Description
The LS7500 Presence/Absence Detector is an adjustable, radio frequency impedance sensing device,
which can be used to detect the presence or absence of material inside a pipe. The basic unit is made up of
a solid stainless-steel flange attached to an explosion proof housing. Inside the explosion proof housing are
all calibration adjustments and sensing electronics. The unit is calibrated in the absence of material and an
internal relay changes state when material is detected.
1.2 Specifications
Electrical
Power: 115 VAC (±15%) 50/60 Hz. 2 watts, standard.
(12 VDC, 24 VDC or 230 VAC optional)
Output: 2 Form C contacts, DPDT relay, 5 amp resistive
At 125, 250 VAC; 30 VDC
Fuse: On board, 250 mA @ 125 volts
Fail Safe: Selectable high or low level
Time Delay: Selectable: ON or OFF delay
Adjustable: 1/8 sec to 2 hrs.
RF Frequency: Approximately 1.3 MHz
Environmental
Enclosure: Cast Aluminum, Class I, Groups C & D; Class II, Groups E, F & G
Temperature: Probe: -30° F to 180° F **
Electronics: -40° F to 185° F
Pressure: Probe: 200 psi @ 75° F**
(**Higher ranges available, consult factory)
Construction: Flange: All wetted parts, 316 SS, Teflon (or UHMWPE) and Viton.
Electronics: Housed in cast aluminum explosion proof enclosure.
Specifications subject to change without notice

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1.3 Ordering Information
LS7500 - 115VAC - FP - 4” 150# - PR
Model #
(LS7500)
Power Supply:
(115VAC 24VDC 12VDC or 220VAC)
Sensor Type:
(FP-Flange Probe)
Sensor Size:
Flange Model:
(PR-Partial Ring or FR-Full Ring)

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1.4 GA Drawing
Figure 1-1
1.5 Sensor Rings
Figure 1-2

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2. THEORY OF OPERATION
The LS7500 employs a radio frequency (RF) balanced impedance bridge circuit to detect if the sensing
element is in contact with the material that is to be sensed. When material is not in contact with the sensing
element, the bridge is balanced by turning the adjustment pot to find the threshold where the red led goes out.
When material is in contact with the sensing element, the bridge becomes unbalanced and the comparing
circuit realizes the change. This causes the relay to change state.
3. INSTALLATION
3.1 Inspection
Carefully unpack the LS7500 from the shipping box and check each item against the packing list before
destroying any packing material. Visually inspect for any damage that may have occurred during shipping.
Please advise the factory or your local distributor of any damage.
3.2 Bench Test
*THIS IS AN EXCELLENT TIME TO BECOME FAMILIAR WITH THE TIME DELAY IF IT IS TO
BE USED IN YOUR APPLICATION. (See calibration instructions, section 7.1 and 7.2)
On the bench, hook up the appropriate power to L1 and L2. The operating voltage of the LS7500 is
marked on the power supply board. Hold the unit so that nothing is touching the flange sensor element is
and press the test switch. When the test switch is depressed, the red led should come on. This simulates
product touching the sensing element. If a timing mode has been selected it will operate as if installed.
NOTE: The timing mode can be adjusted when checking the unit, but the sensitivity adjustment
MUST BE MADE AFTER the unit is installed where it will be used.
3.3 Mounting
3.3.1 Partial-ring Flange Location
The LS7500 is most commonly used for protection of positive displacement pumps in conductive
(water based) media. It is best to install the flange sensor in a position such that fluid will be touching
the sensing element when the pump is running and not touching the sensing element when the pump is
off. Refer to Figure 1-2 for location of the sensing element. When possible, it is preferred that the
sensor flange be mounted in a segment of vertical pipe as close as possible to the inlet side of the
pump or other device to be protected.
CAUTION: ALL INSTALLATION AND WIRING MUST CONFORM TO NEC AND ALL
OTHER LOCAL ELECTRICAL CODES. TAKE SPECIAL CARE IN OBSERVING
HAZARDOUS AREA SAFETY PROCEDURES. WE ASSUME NO LIABILITY FOR
IMPROPERLY INSTALLED OR WIRED UNITS.

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If the LS7500 is mounted in a segment of horizontal pipe, it should be located as close as possible to
the inlet side of the pump or other device to be protected. The housing/NPT of the LS7500 should be
in the 12 o’clock position for 1”-6” flanges and 10 o’clock or 2 o’clock position for flange sizes 7”
and greater. Due to the small size of the sensing element, it is particularly important that larger flanges
(7” and above) be mounted in the 10 o’clock or 2 o’clock position.
The flow of material inside a pipe can be difficult to predict, however experience has shown certain
locations to be better than others. Refer to Figures 3-1 to 3-6 as examples of problematic locations
and preferred locations. Areas to avoid include immediately before or after a 90 degree bend –vertical
or horizontal pipe. In some cases, these areas have created air pockets, thus turning the pump off. In
other cases, these areas have led to excess buildup, leaving pumps to run when they should have been
turned off.
3.3.2 Full-ring Flange Location
Full-ring sensor flanges are primarily used for non-conductive media, such as oils and hydrocarbons.
These sensor flanges can be mounted in either a vertical or horizontal pipe, preferably as close to the
pump inlet as possible. The full ring sensors do not have to be oriented in the 12 o’clock position due
to the fact that the sensor element circles the entire diameter of the flange. Refer to Figure 1-2 for
the sensing element location.
3.3.3 Full-faced Gaskets & Flanges
A full-faced type gasket should be used on each side of the sensor flange. This will help prevent
material build up around the sensing area inside the flange.
NOTE: The sensor flange is designed to mate against full-faced gaskets and full-faced pipeline
flanges. These gaskets should have the same inside diameter as the inside diameter of the pipeline.
Mating against raised-faced flanges and gaskets could cause cracking and improper sealing of the
inner insulator ring of the sensor. Improper gaskets may result in leakage of material inside the
flange causing the pump to run dry and/or into the housing resulting in damage to the electronic
boards.

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SENSOR FLANGE MOUNTING

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3.4 Physical Installation
1) Install the LS7500 Presence/Absence into a recommended or “correct” section of pipe as outlined in
Figures 3-1 to 3-6.
2) Position the orientation of the flange sensor as noted –refer to Section 3.2.1 Partial-ring or Section
3.2.2 Full-ring.
3) Mount the sensor between two 150# or 300# flat faced flanges (raised faced only if ordered raised
face). For use with other flanges contact factory.
4) Use full face gaskets compatible with the process material –refer to Section 3.2.3.
5) Tighten the flange bolts evenly to insure a proper seal.
a) All bolts should be put in place and evenly hand tightened.
b) All bolts should be tightened in 10 ft-lb increments using a star pattern.
c) Torque all bolts to 50ft-lb max.
6) The LS7500 has a 1” NPT conduit entry. When wiring these units, conform to the National Electrical
Code and any other city or company codes.
7) Always install the electrical connection into the 1” NPT on the LS7500 so water will not follow the
connection routing into the threads of the 1” NPT hub. To guarantee that condensation and water will
stay outside the unit, install an EYSM unilet before each LS7500 and fill with explosion proof sealing
cement.
CAUTION: Always take the necessary safety precautions when cutting or welding.
a) Tag and lock out the electrical power to the equipment that services the vessels.
b) Check liquid or dry powders that create a gas in the vessel for oxygen as well as the
explosion factor. (All dust will explode.)
c) Vessels that are cross vented have to be isolated.
3.5 Grounding
Proper installation of the LS7500 is critical to help ensure reliable operations. The most important
installation consideration is a proper sensor ground return. If the vessel is non-metallic (i.e. plastic or
plastic lined), a separate ground return must be provided. In such case, the ground return must consist of a
separate metal mounting flange, installed into a pipeline, adjacent to the sensor flange. A ground wire must
be installed between the ground screw on the sensor flange and the ground screw on the metal ground
flange, as shown in Figure 3-7.
3.6 Ground Continuity Test
Refer to Figure 3-7 below.
1) Turn power to LS7500 off.
2) Use ohm meter on lowest scale to check following:
a) Point A to B –less than 1 ohm
b) Point B to C (both ends of metal pipeline) –less than 1 ohm
c) Plastic Pipeline ONLY –Point B to D –less than 1 ohm