APG KA Cable Suspended User Manual

AUT OMATION

Operator’s Manual

PRODUCTS

GROUP, INC.

KA Series

Liquid Level Controls

Rev . A2, 12/08

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KA Series Rev . A2, 12/08

Table of Contents

Warranty .............................................................................................................3

Introduction ......................................................................................................4

Speci cations ....................................................................................................5

Dimensions ........................................................................................................5

Options ...............................................................................................................6

Chemical Compatibility—Corrosion Resistance ..................................6

Cable Speci cations .......................................................................................7

Switch Wiring and Type Details Table ......................................................8

Selecting the Right Switch ...........................................................................9

Understanding theSwitch Action/Terminology ................................10

Single vs. Dual Point Control .................................................................... 10

Single Point with Timed Relay Control .................................................11

Emptying/Filling Pump Control Circuits ..............................................11

Duplex Pump Control Circuit ...................................................................12

Operating Level Adjustment ....................................................................13

Termination and Height Fixing ................................................................ 14

Position in Tank/Swing Distance Allowance .......................................15

Control Contact Ratings .............................................................................16

Verifying Operation ..................................................................................... 16

Tips ....................................................................................................................17

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Rev . A2, 12/08 KA Series

• Warranty and Warranty Restrictions

APG warrants its products to be free from defects of material and workmanship
and will, without charge, replace or repair any equipment found defective
upon inspection at its factory, provided the equipment has been returned,
transportation prepaid, within 24 months from date of shipment from factory.

THE FOREGOING WARRANTY IS IN LIEU OF AND EXCLUDES
ALL OTHER WARRANTIES NOT EXPRESSLY SET FORTH HEREIN,
WHETHER EXPRESSED OR IMPLIED BY OPERATION OF LAW OR
OTHERWISE INCLUDING BUT NOT LIMITED TO ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.

No representation or warranty, express or implied, made by any sales
representative, distributor, or other agent or representative of APG which is
not specifi cally set forth herein shall be binding upon APG. APG shall not be
liable for any incidental or consequential damages, losses or expenses directly
or indirectly arising from the sale, handling, improper application or use of the
goods or from any other cause relating thereto and APG’s liability hereunder, in
any case, is expressly limited to the repair or replacement (at APG’s option) of
goods.

Warranty is specifi cally at the factory. Any on site service will be provided at
the sole expense of the Purchaser at standard fi eld service rates.

All associated equipment must be protected by properly rated electronic/
electrical protection devices. APG shall not be liable for any damage due
to improper engineering or installation by the purchaser or third parties.
Proper installation, operation and maintenance of the product becomes the
responsibility of the user upon receipt of the product.

Returns and allowances must be authorized by APG in advance. APG will
assign a Return Material Authorization (RMA) number which must appear
on all related papers and the outside of the shipping carton. All returns are
subject to the fi nal review by APG. Returns are subject to restocking charges as
determined by APG’s “Credit Return Policy”.

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KA Series Rev . A2, 12/08

• Introduction

KA series controls consist of a free  oating switch enclosure to which
a protected multiconductor cable is attached. Inside the  oat there are a
number of microswitches set at di erent angles. A control weight is  xed
at a point along the cable to keep the cable immersed in the liquid. The
suspended  oat switch follows the movement of the liquid level. As the liquid
level rises and falls, the weight on the cable causes the inclination of the  oat
to change. This tilting action results in microswitches opening and closing,
sequentially, at di erent elevations. By separating the switching levels,
turbulence problems are overcome. The switch operating levels are easily
adjusted by moving the weight along the cable and/or altering the height of
the cable  xing point.

The switch enclosure is conical
in shape and the required number
of microswitches are cast at
predetermined angles inside it. The
hermetically sealed  oat housing is
 lled with plastic foam and is weighted
on one side. This rugged  oat and
the weight are made of chemically
resistant polypropylene while the
standard cable is PVC coated.

There are two versions of the KA
series switches. The standard series

Alarms Control Plus Alarms
Level IL IH IC 2HL 2L 3L 2H 3H 4L 4H 4L5E 4H5E

(1LE) (1HE) (3LE) (3HE)
HH — — — High — — — High Alarm

Alarm Pumps Alarm
Pump Pump Pump Pump Start Start

H — — — — Stop Start Stop Start Pump Pump
No.1 No.2

Pump Pump Pump Pump Start Start
L — — — — Start Stop Start Stop Pump Pump
No.2 No.1

LL Low High High/Low Low — Low — — Low Alarm
Alarm Alarm Alarm Alarm Alarm Pumps

O Height of Face of Float in Free-Hanging Position

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Stop Both

High

Stop Both

Rev . A2, 12/08 KA Series

• Specifi cations

Standard Series M Series
Contact Rating: Maximum Voltage 250 V AC or DC 250 V AC or DC
Maximum AC Current (Resistive) 6 A 6 A
(Inductive) 3 A 3 A
Maximum DC Power

75 VA (=0.3 A @ 250 V) 75 VA (=0.3 A @ 250 V)
Maximum liquid Temperature 60°C (140°F) 60°C (140°F)
Maximum pressure (at 20°C) 28 PSI 28 PSI
Minimum Fluid Speci c Gravity 0.7 0.95
Standard Cable Length* 16 ft. 16 ft.
Switching Di erential: Minimum 10 in. 10 in.
Maximum 50 in. 40 in.
Maximum Number of Switching Levels 4 2
Maximum Number of wires in Cable 5 2
Standard Weight Type G (black-3/4 lb.) G (black-3/4 lb.)

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KA Series Rev . A2, 12/08

• Options

Higher working temperature to 80°C (175°F): Model -K
Longer cables to speci ed lengths
Smaller switching di erentials down to 1.25 in.
Greater switching di erentials to 75 in. (Standard series) or 60 in. (M series)
Alternative logic at switching points (normally open vs. normally closed)
Alternative cables in rubber and urethane
Alternative cables in te on, (max. 4 conductors = 3 or less switch points)
Lead weight in place of polypropylene-covered weight

• Chemical Compatibility — Corrosion Resistance of Materials

With a standard KA  oat switch, the only materials in contact with the liquid
are the polypropylene covered  oat and weight, the heavy duty PVC coated
cable, and the polypropylene wedge. Consequently, these switches are
una ected by a wide range of liquids. However, there are some liquids that
are not compatible with these materials. For such applications, alternative
construction materials are available as indicated in the Options section
above. In assessing corrosion, key factors are the liquid temperature and
concentration, and the amount of time the  oat is immersed. Even if periodic
replacement of KA  oat switches is necessary, they still may be the most
economical choice. Rubber cables are preferred for applications where
freezing conditions can occur, because the PVC coated cable tends to sti en
in such situations.

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Rev . A2, 12/08 KA Series

• Cable Specifi cations

Single level switches (high or low alarm) are not supplied with weights. All
multiple level switches are supplied with standard weights. Heavier weights
may be needed if there is a danger of caking, thick crusts developing and/or
the liquid is very dense and viscous. Alternative weights available are:
Standard: Type A (black) 3/4 lb.
Special: Type B (red) 1-1/2 lb. Type C (grey) 2-1/2 lb.

Standard units have heavy duty cables with PVC covering. Typical diameters
of the cables are:

2-Wires (1L, M1L, 2L, M2L, etc.): 0.25 in.

3-Wires (3L, 3H, etc.): 0.27 in.

4-Wires (4L, 4H, etc.): 0.31 in.

5-Wires (4L5E, 4H5E, etc.): 0.34 in.

(Dimensions may vary ±10%)

An integral cable, without splices, or greater length than the standard 16 feet
may be needed for some situations and this can be supplied by special order.
It is not possible to modify the cable length (nor repair damaged cables) on
existing units. Once the cable is outside the liquid, it can, however, be easily
extended through a waterproof junction box or liquid tight connector.

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KA Series Rev . A2, 12/08

• Switch Wiring and Type Details for KA Float Switches

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Rev . A2, 12/08 KA Series

• Selecting the Right Switch

The following procedure should be used to select the optimum switch or
switch combination:

1. Determine the number of control points needed; for example, one point
for alarm, two points for empty/ ll, etc.

2. Select required model(s) from the Type Detail Table. If necessary, special
switches may be ordered with nonstandard switching logic.

3. The smaller, lower cost M series switches may be used if the three
following conditions are met:

a. No solid  oating materials are present
b. The speci c gravity of the liquid is greater than 0.95
c. No more than a two conductor cable is needed

4. Note that if a special material compatibility situation exists, there are a
number of options available as indication in the Options section on page

5.

This publication describes how the switching levels are related and
how they are adjusted. If it is found that the required levels cannot be
accommodated by standard units, a special switch can be ordered. For use
in still liquids, a two level switch with a smaller di erential than the standard
minimum (10 inches) may be ordered. Sometimes a combination of switches
needs to be used to achieve the required switching heights or range of
adjustment capabilities. For example a Model 3HE can be replaced by a model
2H plus a separate model 1H, or a model 2LH by a model 1H plus model 1L.
Our Applications Engineering Department is pleased to assist users to select

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KA Series Rev . A2, 12/08

• Understanding the Switch Action/Terminology

In order to understand the operation of KA liquid level controls, imagine
them operating like pushbutton switches. A normally open (NO) switch is one
that is open when there is no liquid present and closes as the liquid rises. Such
a switch is symbolized as in Diagram 1. The opposite action normally closed
(NC) switch operates as in Diagram 2. Note that the term “normally” means the
switch state when there is no liquid present — it does not mean the “usual”
operating state of the switch.

• Single Versus Dual Point Control

The simplest single level KA  oat switches (types 1L or 1H) have no deadband
(= di erential or hysteresis). They switch ON and OFF at one level point. Such
switches work well as alarm point indicators but are unsuitable for automatic
maintenance of the level of liquids in containers.

Usually, tank levels are maintained by pumps or electrically controlled
solenoid valves in the supply or drain lines. Holding the level exactly at one
point is di cult if there is  ow in and out of the container, because it would
involve the control switch going on and o constantly. This leads to excessive
wear of the components. Thus, the normal practice is to have two control
levels involved. At one level the pump or valve is turned ON and at the other
level it is turned OFF.

These situations can take advantage of the unique capabilities of the KA  oat
switches. Rather than using two separate single level  oat switches, one  oat
switch (type 2L or 2H) can provide ON and OFF level controls. The absolute
height and separation (deadband) of these points can be easily adjusted.
The ON control is a “make” in the circuit and the OFF is a “break” in the circuit.
The deadband is supplied by the  oat switch. Other KA  oat switches provide
additional facilities for high and low alarms as well as control of duplex pump

10

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Rev . A2, 12/08 KA Series

• Single Point with Timed Relay Control

There may be some situations where it is not possible to produce any form of
dual level control. In such cases an e ective deadband can be produced with
a single level switch by using it in conjunction with a time delay relay. When
the switch operates, it turns on the relay which stays on for a predetermined
period so that the pump or valve operates for that set period each time that it
is turned ON.

• Emptying/Filling Pump Control Circuits

Simple Filling (Pump up) Control (Using Type 2L)

Simple Emptying (Pump down) Control with High Level Alarm
(Using Type 3HE plus manual override)

Note: In the above examples, the relay contact R1A is used to electrically latch the relay ON
in manual use. If the pump is manually started the  oat switch will not turn OFF. (The relay/
contactor R1 used should be a DPST type with suitable ratings on one contact (R1B) able to carry
the voltage and current required by the pump motor horsepower rating. If the pump motor
requires three phase power, the relay contact R1B would have to comprise three poles of heavy
duty NO switches capable of carrying the pump motor power as well as there being an auxiliary
NO switch contact R1A for latching purposes. Heavy duty relay contactors of this type are readily
available

at most electrical supply houses.

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KA Series Rev . A2, 12/08

Alarm Bell or Light

Alarm
Power

Line

Power

R1B

R2B

Pump Alternator

Power to

Lead Pump

Power to

Lag Pump

R1

R2R2A

High Alarm

Point

Lag Pump (#2)

ON

Lead Pump (#1)

ON

Both Pumps

OFF

4

5

1

3

1

2

• Duplex Pump Control Circuit (Using Type 4H5E)

Note: Usually an alternator control is added to the lead and lag pump control circuits. This
control automatically alternates the order in which the two pumps come on. In this way the wear
on the pump is evened out. If this is not done, in the course of time, the user will have one (lead)
pump that is well worn and one (lag) pump that is barely used. If the pumps use three phase
power, the single pole switch contacts, R1B and R2B, would need to be heavy duty three pole
switch contacts.

12

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Rev . A2, 12/08 KA Series

• Operating Level Adjustment

Switch operating levels depend on the height at which the  oat is
positioned in the tank by the cable fastening and the distance along the cable
between the  oat and the weight. The Termination and Height Fixing section
on the next page of this manual discusses the methods for securing the cable
at the required height. The height of the face of the  oat in the free hanging
position, with no liquid present, is used as a zero reference for adjusting all
switch point operating levels per the graph and diagram below. Level settings
may vary slightly between switches. Final adjustments should be made under
actual pumping conditions. If there is surface wave motion, some variation in
actual switching levels may occur.

For single level types (1L, 1H, 1C, 1LE and 1HE), the  oat should be hung
so that the desired switching point is 5 inches above the zero reference. This
represents the di erence in height between levels O and LL. Note that these
single level switches do not require a weight on the cable for their tilting
operation.

For multi level types, the distance A (from zero reference 0 to weight) has
to be adjusted to obtain the desired switching di erential. For most switches
the di erential height B between levels H and L is the crucial dimension. The
required value for B, together with the corresponding value of A, is selected
from the graph shown on the next page. Then, if the weight is wedged at
that distance and the  oat hung in accordance with the diagram, the switch
points will operate with the correct di erential. The graph gives the distance
C between levels H and HH for the determined value of A. It will be seen that
switching levels HH and LL bear a speci c relationship to A and B and cannot
be independently adjusted. Thus, if it is essential to be able to adjust these
levels separately, two  oats may be needed rather than just one.

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KA Series Rev . A2, 12/08

As a working
example, consider
a type 4H needing
a pump operating
di erential of 20
inches (= dimension
B). From the graph it
can be seen that the
corresponding value
for A is approximately
19 inches. Now
suppose that the
 oat is to operate
in a tank so that the
pump “o ” position (level L) is 15 inches from the bottom of the tank. This
means that the  oat must be hung so that the zero reference height (free­hanging face of the  oat) is 6 inches from the bottom of the tank. The high
and low alarm points HH and LL will then be, respectively, close to 41 and 11
inches from the bottom of the tank.

For type 2HL, the di erence between the high and low alarm points is the
di erence between levels LL and HH in the graph. Note that this corresponds
to distance B + C + 4 inches and the distance A for weight positioning must be

• Termination and Height Fixing

There are several methods that can be used to fasten the cable so that the
 oat is positioned at the right level in the tank. The three most commonly
used are illustrated below. Very frequently, the cable will need to be led into
a standard NEMA box with terminals for extension to the control panel. The
liquid tight (70PSI) Strain Relief Connector (Part# SRCG) can be used to lead
the cable through the wall of the box.

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Rev . A2, 12/08 KA Series

• Position in Tank/Swing Distance Allowance

KA  oat switches should hang freely in the tank and not be tightly tethered.
If more than one  oat switch is to be installed in the tank, the cable  xing
points should be separated to prevent the cables from tangling. The  oat
switches do not need to be hung in the center of the tank — the cable can
run down a wall or corner of the tank as illustrated below.

The  oat switches need a certain free surface to operate in. As a rule of
thumb, the swing radius to be allowed should be the same as the distance of
the weight from the bottom of the  oat. If necessary, ba es or stilling wells
may have to be provided to prevent interference with other equipment.
Contact our Applications Engineering Department for alternative suggestions
if any di culties in this regard are foreseen.

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KA Series Rev . A2, 12/08

their motors. These allow the KA  oat switches to be connected directly. If
contactors are not provided, the contact ratings needed to start and stop
a pump should be approached with caution: when pump motors start and
stop, they can produce a momentary surge current several times greater
than the steady running current. Suppliers of the relays and contactors
usually provide maximum ratings for their contacts in terms of allowable
pump motor horsepower  gures. If there are any concerns in this regard,
consult our Applications Engineering Department for advice.

• Verifying Operation

KA  oat switches are highly reliable. However, if a check on the operation
of a particular switch is needed, it is  rst necessary to ascertain where the
bias weight is located in order to  nd the top point when the  oat is in
the liquid. A good way to do this is to put the  oat switch on a  at surface
so that it can roll freely to the working orientation (just like it does in the
liquid). A continuity meter should then be attached to the circuit to be
tested. Testing is then performed by tilting the  oat up and down in the
vertical plan determined by the working orientation. At the appropriate
angle, the switch circuit being tested should open or close.

• Valuable Tips

1. Do not be concerned if you hear a clacking sound when the  oat is
shaken — it is only the microswitch acting. It is extremely unusual to
 nd any leakage in these  oats.

2. Do not put the full line power voltage across a contact without a load
attached. Shorting out the power across the microswitch will destroy it.

3. Do not tether the  oats tightly on a short cable or make them jiggle
and dance in a high pressure washdown hose stream. The continuous
 exing at a particular point in the cable will break the wires.

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Rev . A2, 12/08 KA Series

• Control Contact Ratings

The contacts used in the KA  oat switches are high performance
microswitches. Although they are capable of carrying quite high currents at
up to 250 VAC, it is not a good practice to put pump motor currents directly
through these contacts because they are immersed in the liquid. Thus, it is
usually just low sensing currents for relay coil operation that are applied to
the  oat switch contacts.

Relays with heavy duty contacts are known as contactors. Pump motor
manufacturers often provide suitable contactors with control circuits on

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AUT OMATION

PRODUCTS

GROUP, INC.

APG...Providing tailored solutions
for measurement applications

Automation Products Group, Inc.

Tel: [phone]
1/435/753-7300
Fax: [phone]

e-mail: [e-mail]

www.apgsensors.com

Automation Products Group, Inc.

1025 W. 1700 N.

Logan, UT 84321