Kenco Engineering Thermal Differential Switch User Manual
KENCO ENGINEERING COMPANY
P.O. BOX 470426 TULSA, OK 74147-0426 ● PHONE: (918) 663-4406 FAX: (918) 663-4480
www.kenco-eng.com e-mail: info@kenco-eng.com
SERIES KTD THERMAL DIFFERENTIAL FLOW/LEVEL SWITCH
INSTALLATION / OPERATION INSTRUCTIONS
TABLE OF CONTENTS
1. GENERAL DESCRIPTION ............................................................. 2
2. PRINCIPLE OF OPERATION ......................................................... 2
3. MODEL DESCRIPTION .................................................................. 2
4. INSTALLATION .............................................................................. 3
5. WIRING CONNECTIONS................................................................ 4
6. OPERATIONAL CHECK................................................................. 5
7. PRE-CALIBRATION ....................................................................... 5
8. CALIBRATION (Level Switch)....................................................... 6
9. CALIBRATION (Flow Switch)........................................................ 7
10. MAINTENANCE & TROUBLESHOOTING ..................................... 8
11. SPECIFICATIONS .......................................................................... 8
Page 1
GENERAL DESCRIPTION
Options
Options (cont.)
Options (cont.)
Options (cont.)
Model
Sensor Materi
al
provides the cooling effect. In other words, the lower the flow rate the greater the temperature differential between the
The Series KTD Thermal Differential Switch is the state-of-the-art in gaseous and liquid flow switching or liquid level /
interface control. Flow or level detection is accomplished by using a high resolution thermal differential technique. The
standard sensor wetted parts are of durable 316L series stainless steel, all welded construction with no moving parts. The
switch is easy to install and adjust, giving reliable, low maintenance performance in the most demanding applications.
PRINCIPLE OF OPERATION
The Series KTD Thermal Differential Switch uses a thermal differential technique to measure liquid level or interface
by sensing changes in the thermal heat transfer characteristics of the media where it is located. The sensor consists
of a pair of matched Resistance Temperature Detectors (RTD’s) encased in twin 316 series, stainless steel tubes.
One RTD is self-heated using a constant DC current. The other sensor is unheated and provides an accurate ambient
process temperature reference. The thermal differential created between the heated and reference RTD pair is
a function only of the media with which the sensor is in contact. The differential is greatest when no liquid is present
(dry condition) and decreases as liquid quenches the switch sensors (wet condition).
Hydrocarbons generally have lower heat-transfer characteristics than aqueous-based materials so liquid-liquid
interface detection is possible. In general, any two media will exhibit some difference in heat-transfer characteristics.
Thus, the switch can be calibrated to detect the interface between two immiscible liquids.
This switch can also be used as a no-flow or a low flow switch. In this case the actual flow of the liquid or gas
(2) RTD’s.
Solid-state electronics transform the temperature differential into a voltage that is compared to a control voltage to
actuate a relay and indicate a change in state (wet vs. dry). The instrument head at the top of the unit contains the
Switch electronics board which is easily removable from the instrument head so that field wiring can be connected to
the field terminal block.
MODEL DESCRIPTION
Model
Process Connection
Sensor Material
Insertion Length (Inches)
Input Power
Configuration
- - - - - -
Options
Description Code Description Code Description Code Description Code
No Options 00 Extended Neck EN Additional Cable CA SS Tag TG
RTD Output RT *High Temp (850ºF) HT Variable Insertion VI
Live Tap LT *Medium Temp (572ºF) MT Factory Calibration CB
CE Approved CE Explosion-proof Window XW Thermocouple Output TO
* Remote Mounting Required
Description Code Description Code
Level Switch KTDL 316L SS S6
Flow Switch KTDF 304 SS S4
304L SS SL
Process Connection
Hastelloy-B HB
Description Code Hastelloy-C HC
½” NPT 050 Inconel 600 IO
¾” NPT 075 Monel MN
1” NPT 100 Alloy-20 A2
1½” Sanitary 3A1 Special Material SM
1” 150# ANSI Flange RA1
2” 150# ANSI Flange RA2
Input Power
1” 300# ANSI Flange RB1 Description Code
2” 300# ANSI Flange RB2 110 Vac 110
Low Flow Sensor LFS 220 Vac 220
Special Connection SPL 24 Vdc 24D
Configuration
Description Code
24 Vac 24A
Insertion Length
Integral Mounting LE 002.00 (standard)
Remote Mounting RE 000.50 – 120.00 (optional)
Sensor
Installed in
TE
Tee
Page 2
INSTALLATION
Unpack the switch carefully. Inspect all units for damage. Report any damage to carrier immediately. Check the
contents against the packing slip and purchase order.
Kenco’s Thermal Differential Flow / Level Switches are manufactured to the highest quality standards. These instruments
use electronic components that can be damaged by static electricity. Make sure that you are properly grounded before
starting installation. Insure that all electrical connections are properly made, and that there are no “floating” connections.
Mechanical Installation
The Series KTD Switches have a ¾” NPT (standard) process connection. When used as a level / interface switch, and
horizontally mounted, the sensor must be oriented so that the RTD’s are parallel with the liquid surface. When used as a
flow switch the sensor must be oriented so that the RTD’s are perpendicular with the flow direction.
Use a 1-1/8” open end wrench to tighten the sensor in the process connection. Use the hex flats on the sensor for
tightening. DO NOT use the instrument housing for tightening. Rotation of the instrument housing in respect to the
sensor can cause internal wiring damage, and will void the warranty.
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