BABBITT LS7500 User manual

www.babbittinternational.com Reference Manual
2020 Rev.2
LS7500 Presence/Absence Switch
OWNERS MANUAL
♦INSTALLATION
♦CALIBRATION
♦TROUBLESHOOTING
♦WARRANTY
P.O. Box 70094
Houston, TX 77270
[phone]

www.babbittinternational.com Reference Manual
2020 Rev.2
Read this manual before working with the product. For personal and system safety, and for optimum product
performance, make sure that you thoroughly understand the contents before installing, using or maintaining this
product.
For equipment service or support needs:
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.
Explosions could result in death or serious injury.
Verify the operating environment of the Babbitt LS7500 Presence/Absence switch is consistent with the
appropriate location certifications.
Do not remove the housing cover in explosive atmospheres when the circuit is alive.
To prevent ignition of flammable or combustible atmospheres, disconnect power before servicing.
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

www.babbittinternational.com Reference Manual
2020 Rev.2
TABLE OF CONTENTS
Page
1. Description ------------------------------------------------------------------ 1
A. General Description --------------------------------------------- 1
B. Specifications -----------------------------------------------------1
C. Ordering Information---------------------------------------------1
2. Theory of Operation -------------------------------------------------------3
3. Installation-------------------------------------------------------------------3
A. Inspection and Operation Check ------------------------------- 3
B. Physical Installation ----------------------------------------------3
C. Removing Electronics -------------------------------------------- 4
D. Typical Applications and Wiring Diagrams -------------------4
1) LS7500 Terminal Layout --------------------------------4
2) Ladder Diagrams -------------------------------------- 6-7
4. Calibration -------------------------------------------------------------------8
A. Setting the Time Delay ------------------------------------------ 8
B. Fail Safe Selection ------------------------------------------------8
C. Sensitivity Calibration ------------------------------------------- 9
5. Maintenance and Troubleshooting --------------------------------------10
6. Warranty ------------------------------------------------------------------- 11

www.babbittinternational.com Reference Manual
2020 Rev.2
LS7500 PRESENCE/ABSENSE SWITCH
1. DESCRIPTION
A. General Description
The LS7500 is a level switch that detects the presence or absence of material in 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.
B. 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
Hazardous Area: Housing is CSA and UL approved for Class I, Div. 1, 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.
A Halar coating can be applied to the flange when applicable.
Electronics: Housed in cast aluminum explosion proof enclosure.
Specifications subject to change without notice.
C. Ordering Information
LS7500 - 115VAC - FP - 4” 150# -PR
Model #
(LS7500)
Power Supply:
(115VAC 24VDC 12VDC or 220VAC)
Sensor Type:
(FP-Flange Probe or TC-Tri-Clamp)
Sensor Size:
Flange Model:
(PR-Partial Ring or FR-Full Ring) 1

www.babbittinternational.com Reference Manual
2020 Rev.2
2

www.babbittinternational.com Reference Manual
2020 Rev.2
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
A. Inspection and Operation
After unpacking the LS7500, visually inspect the unit for any damages. Please advise the factory or your
Local distributor of any damage. Before installing the unit, a simple operational check can be performed.
*THIS IS AN EXCELLENT TIME TO SET THE TIME DELAY IF IT IS TO BE USED IN YOUR
APPLICATION. (See calibration instructions, section 4, A)
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 the probe is not touching any surface and press
the test switch. When the test switch is depressed, the red led should come on. This simulates product
touching the probe. 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.
B. Physical Installation
1) The LS7500 is installed into the piping wall using a flange.
2) CAUTION: Always take the necessary safety precautions when cutting or welding in the
coupling for the LS7500.
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) Tighten the LS7500 into place using proper gaskets and sufficient torque to prevent leaks.
4) 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.
5) 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.
3
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.

www.babbittinternational.com Reference Manual
2020 Rev.2
C. Removing the Electronics
1) To remove the sensing card, simply unplug it from the power supply card. When reinstalling, this card
is made so that it cannot be plugged in backwards.
2) To remove the power supply card you must:
a) Disconnect supply power at main power source.
b) Remove sensing card.
c) Disconnect wires from terminal strip.
d) Remove green grounding screw.
e) Unplug blue antenna lead.
f) Hold the top of the card guide and lift out
NOTE: LS7000 AND LS7500 ELECTRONIC COMPONENTS ARE INTERCHANGABLE.
D. Typical Applications and Wiring Diagrams
LS7500 TERMINAL LAYOUT
*NOTE: EACH LS7500 POWER SUPPLY IS INTENDED FOR ONLY ONE SUPPLY VOLTAGE. THIS
VOLTAGE IS PRINTED ON THE POWER SUPPLY BOARD. FOR 115 VAC OR 230 VAC UNITS, HOOK UP THE
HOT LEAD TO L1 AND THE NEUTRAL TO L2, WITH APPROPRIATE GROUND. FOR 12 VDC OR 24 VDC
UNITS, HOOK THE POSITIVE VOLTAGE TO L1 AND THE COMMON OR GROUND TO L2.
4

www.babbittinternational.com Reference Manual
2020 Rev.2
NOTE: LS7000 AND LS7500 ELECTRONIC COMPONENTS ARE INTERCHANGABLE.
5

www.babbittinternational.com Reference Manual
2020 Rev.2
6

www.babbittinternational.com Reference Manual
2020 Rev.2
7

www.babbittinternational.com Reference Manual
2020 Rev.2
4. CALIBRATION
PLEASE READ THE ENTIRE CALIBRATION PROCEDURE BEFORE CALIBRATING THE LS7500.
If no time delay is required, turn the time adjustment pot completely CCW and set S1 down, S2 up. The
potentiometer has 18 turns and freewheels at the end of its travel without damage. You may hear “clicks” at
the end of travel.
A. Setting the Time Delay
1) Setting the timing mode, either on delay or off delay is done by positioning S3 and S4 as shown in the
chart below.
NOTE: S3 and S4 also select fail safe high level (FSH) or fail safe low level (FSL).
2) Select the timing range using S1 and S2 as shown on the chart below.
3) Adjust the time adjustment potentiometer clockwise to increase time or CW to decrease until the exact
time delay is arrived at. The test switch may be depressed to start the timing when checking timing
sequence.
NOTE: For long timing ranges you can set the timer for a shorter range, then change the range
Switches (S1 and S2) to increase the time. For example, the desired time delay is 15
minutes. This is equal to 900 seconds. By setting S1 down and S2 up and adjusting the
timer to approximately 28 seconds, the ratio on this range is 1. To increase this range by
32, move S1 up and S2 up. 32x28 seconds equals approximately 15 minutes.
B. Fail Safe Selection
The failsafe feature provides a “false alarm” in case of power outage or major component failures. When
properly selected, the failsafe feature can protect equipment or alert you of a unit failure. Fail Safe High
(FSH) means that the relay is energized when NO PRODUCT is touching the sensing element. The green led
indicates relay status and is on when the relay is energized. When product comes into contact with the sensing
element, the relay is de-energized. Fail Safe Low (FSL) means that the relay is energized when PRODUCT IS
touching the sensing element.
8
NOTE: Due to the wide variety of applications and possible control or alarm functions, the proper
fail safe selection will depend on your circumstances. Please call your distributor or the factory if
you need assistance.

www.babbittinternational.com Reference Manual
2020 Rev.2
C. Sensitivity Calibration
The LS7500 should be calibrated when no material is touching the sensing element and when the unit is
installed where it will be used.
NOTE: Dirty pipe calibration –DO NOT CLEAN SENSING ELEMENT –simply follow the same
procedure below with the buildup in place.
1) Observe the red LED. If it is on, go to step 3.
2) If the red LED is off, turn the sensitivity adjustment potentiometer CW until it comes on.
3) Turn the sensitivity adjustment pot CCW until the red LED just goes out and continue to turn the pot
CCW at least ½ of a turn. This sets the unit to its maximum stable sensitivity. If in your application this
is too sensitive, you can turn the sensitivity adjustment pot further CCW. Always bring the product into
contact with the sensing element after calibration to assure proper performance.
NOTE: The green LED indicates relay status. The relay is energized when the green LED is on.
Every LS7500 has a diagram inside the screw cover to serve as a reminder to those who have
calibrated the unit before. This shows the calibration adjustments and indicators. This diagram is
reproduced below.
SPECIAL CALIBRATION NOTES:
For some products, the LS7500 can be calibrated with product touching the sensing element. To do
this, turn the sensitivity adjust pot CW until the red LED just comes on and continue CW for 1/8 to ¼
of a turn. Always check to see if the unit resets in the absence of product.
9

www.babbittinternational.com Reference Manual
2020 Rev.2
5. MAINTENANCE AND TROUBLESHOOTING
No routine maintenance is required other than keeping the interior of the unit clean and free of dirt, dust and
other contaminants. The LS7500 consists of three main sub-assemblies. These are the enclosure with the
flange assembly, the power supply board and the sensing card. The following troubleshooting guide will assist
in determining how to correct most of the problems which may occur in the field. Review the Installation and
Calibration procedures in sections 3 & 4.
PROBLEM POSSIBLE CAUSE SOLUTION
RED LIGHT cannot be Antenna lead not connected. Plug antenna lead into flange.
adjusted to turn on. No power to unit. Check for correct power to unit.
Blown on-board fuse. Replace fuse.
Bad sensing card. Repair or replace card.
RED LIGHT remains on at Sensing element is shorted to Unplug banana plug and position
Times ground it so that the bare end is not
touching anything. Turn calibration
pot 20 turns CCW. LED should go
out. If it does, repair, replace or clean
antenna probe. If LED does not go
out, replace electronics.
Bad sensing card. Repair or replace card.
Unit triggers when material Improper mount of sensing element. Contact factory or distributor.
touches sensing element, Improper calibration procedure. See Section 4C.
but will not reset when Excessive material build-up on Perform “dirty pipe” calibration;
material recedes from sensing sensing element. Recalibrate with buildup material on
element or unit gives false sensing element. See section 4C.
alarm.
PROBLEM POSSIBLE CAUSE SOLUTION
Unit will not detect material Improper calibration See calibration instructions section
4.
Antenna lead not plugged into Plug antenna lead into flange.
flange.
Unit was calibrated with material Be sure material is not touching
touching sensing element. Sensing element and recalibrate
Unit will not stay in Poor grounding of unit to pipe. Provide secure grounding
calibration. connection.
Relay operates properly, but Burned or broken lands on the Turn off power. Remove
no signal at terminals. printed circuit board. module from housing and inspect
lands on printed circuit for damage.
Replace if necessary.
Bad relay contacts. Replace relay or return for repair.
PLEASE CONTACT THE FACTORY OR YOUR DISTRIBUTOR IF YOU HAVE ANY QUESTIONS OR
NEED ASSISTANCE.

www.babbittinternational.com Reference Manual
2020 Rev.2
6. WARRANTY
All components of the LS7500 are warranted to be free from defects in material and workmanship for a
period of two years from the date of purchase . This warranty applies to general purchaser and to
components installed, serviced and operated according to instructions.
Babbitt International, Inc. will repair or replace, at its option, FOB at its plant or any other location
designated, any part which proves to be defective in manufacture or workmanship.
All claims must be made in writing within the warranty period. No claims outside of the warranty period
will be honored.
Warranties are not applied to any components which have been damaged by improper installation, use,
exposure to unusual atmospheric conditions or components which have been misused, abused, damaged
by neglect or accident. This warranty shall not apply to any components which have been altered or
repaired without the prior written consent of Babbitt International, Inc.
Babbitt International, Inc. assumes no responsibility or liability for any labor or material back charges,
without written authorization. Any products returned must be with prior written authorization.
THE FOREGOING IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED,
INCLUDING ANY WARRANTIES OF MERCHANTABILITY AND/OR FOR FITNESS
FORPARTICULAR PURPOSE, AND BABBITT INTERNATIONAL, INC. ASSUMES NO
OTHERLIABILITIES EXPRESSED OR IMPLIED. BABBITT INTERNATIONAL, INC. SHALL NOT
BELIABLE FOR NORMAL WEAR AND TEAR, NOR FOR DIRECT, INCIDENTIAL
ORCONSEQUENTIAL DAMAGES. IN NO EVENT SHALL BABBITT INTERNATIONAL
INCORPORATED’S LIABILITY EXCEED THE PRICE OF ITS PRODUCT AT THE TIME OF
PURCHASE.
11