Danfoss KP 34, KP, KP 35, KP 36, KP 37 Data sheet

Data Sheet

Pressure switches and thermostats
Type KP

For steam, air, gaseous and liquid media

KP Pressure Switches

Danfoss KP switches are used for regulating,
monitoring and alarm systems in the industry.
They provide automatic limit protection or
manual reset limit protection for pressure
systems. Can be used with steam, air, gaseous
and liquid media.

The pressure switches are tted with single­pole changeover switch (SPDT). The position of
the switch depends on the setting of the
pressure switch and the pressure in the
connector.

KP Thermostats

KP thermostats are temperature-operated
electric circuit breakers. The thermostats are
tted with single-pole changeover switch
(SPDT)

The position of the switch depends on the
thermostat setting and sensor temperature. A
KP thermostat can be connected and switch to
single-phase alternating current motors of up
to 2 kW.

AI209986438809en-000602

123456789101112131415

Key sketch of KP pressure switch

Simplied drawing of KP pressure switch without front cover and scale.

Version with manual reset.

Range setting spindle

Dierential setting spindle

Main arm

Main spring

Dierential spring

Bellows

Pressure connector

Contact system

Switch terminals

Ground terminal

Cable entry: ½ in female NPSM

Tumbler

Locking screw

Manual reset

Distance plate

Pressure switches and thermostats, Type KP

Features

• Wide regulating range

• Small dimensions
⁃ Space-saving, easy to install in panels

• Shock and impact resistant

• Ultra-short bounce time. Limits wear to an absolute minimum and increases reliability

• Snap action electrical contacts minimize chatter, bounce, and wear, and ensure long term electrical and

mechanical reliability

• Electrical connection from front of the unit. Makes rack mounting easier and also saves space

• Suitable for alternating current and direct current

• Screwed wiring, makes rewiring easy

• Manual trip allows electrical function test without tools

• Versions with automatic and manual reset available

Functions

Pressure switches

Table 1: Design and function

The contact system of KP switches has a snap-action function and the bellows moves only when cut-in or cut-out
set point is reached.

The design has the following advantages:

• higher contact load

• ultra short bounce time

• long mechanical and electrical lifetime

• high resistance to vibrations and pulsations

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1011121314

15

Key sketch of KP 79, KP 81 thermostats

Simplied drawing of KP thermostat without front cover and scale.

Version with manual reset.

Range setting spindle

Dierential setting spindle

Main arm

Main spring

Dierential spring

Bellows

Temperature sensors

Contact system

Terminals

Ground terminal

Cable entry: ½ in female cable

gland

Tumbler

Locking screw

Manual reset

Distance plate

Pressure switches and thermostats, Type KP

Thermostats

Table 2: Design and function

The contact system of KP switches has a snap-action function and the bellows moves only when cut-in or cut-out
set point is reached.

The design has the following advantages:

• higher contact load

• ultra short bounce time

• long mechanical and electrical lifetime

• high resistance to vibrations and pulsations

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Features

Descriptions

Ambient temperature

-40 – 150 ˚F (175 ˚F for short period of time)

Media temperature

-40 – 212 ˚F

Sensor material

Tinned copper Cu/Sn5

Parts in contact with medium:

Bellows:

Stainless steel

Pressure connection:

Free-cutting steel, nickel plated

Wire dimension

12 AWG max.

Contact system

SPST (close on temp. rise), SPDT

Contact material AgCdO

Contact load

Alternating current

FLA

0.5 ~ 16 A/120 V AC

0.5 ~ 8 A/240 V AC

LRA

96 A/120 V AC
48 A/240 V AC

Direct current

240 V DC: 12 W pilot duty

Enclosure

NEMA ~1 (when mounted on a at surface with all unused holes covered)

Cable entry

Integral ½ in female NPSM swivel cable connector, allows direct attachenments of ½ in. male
pipe thread connector

Features

Descriptions

Ambient temperature

-40 – 150 ˚F (175 ˚F for short period of time)

Sensor material

Tinned copper Cu/Sn5

Wire dimension

12 AWG max.

Contact system

SPDT – single pole double throw

Contact load

Alternating current

FLA

0.5 ~ 16 A/120 V AC

0.5 ~ 8 A/240 V AC

LRA

96 A/120 V AC
48 A/240 V AC

Direct current

240 V DC: 12 W pilot duty

Enclosure

NEMA ~1 (when mounted on a

at surface with all unused holes covered)

Cable entry

Integral ½ in female NPSM swivel cable connector, allows direct attachenments of ½ in. male
pipe thread connector

Switch type - single pole double throw

Switch action

Application

Terminals 1 – 4 close high and open low
Terminals 1 – 2 can be used as low pressure alarm

Low pressure cut-out

Terminals 1 – 2 open high and close low
Terminals 1 – 4 can be used as high pressure alarm

High pressure cut-out

Pressure switches and thermostats, Type KP

Product specication

Technical data

Pressure switches

Table 3: Technical data

Thermostats

Table 4: Technical data

Contact system and application

Pressure switches

Table 5: Contact system and application

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Switch type - single pole double throw

Switch action

Application

Terminals 1 – 4 close high and open low
Terminals 1 – 2 can be used as low temperature alarm

Low pressure cut-out

Terminals 1 – 2 open high and close low
Terminals 1 – 4 can be used as high temperature alarm

High pressure cut-out

Pressure switches and thermostats, Type KP

Thermostats

Table 6: Contact system and application

Setting

Pressure switches

Cut-in and cut-out pressures of the system should always be checked with an accurate pressure gauge.

Pressure setting for switches with automatic reset.

Set the cut-out pressure on RANGE scale and dierential on DIFF scale.

NOTE:



Restart pressure is equal to cut-out pressure minus dierential value.

Pressure switches with manual reset

Set the cut-out pressure on the RANGE scale. Pressure limiters can be manually reset by pressing reset button when
the pressure is equal to the cut-out pressure minus xed value of the dierential.

Thermostats

Thermostats with automatic reset

Set the cut-out temperature on the RANGE scale and dierential on the DIFF scale. Restart temperature is equal to
the cut-out temperature minus dierential value.

 NOTE:

The dierential scale is only a reference. The exact value of distances on the scale depends on where in its range the
switch cut-in is set. Use the dierential scale as a guide, and if precise function is required, establish the dierential
setting by comparing function with an accurate thermometer in the controlled zone.

Thermostats with manual reset

Set the cut-out temperature on the range scale.

The dierential is xed. Restart the system by pressing the reset button after the temperature of the sensor falls to a
value equal to the range scale setting minus the xed dierential.

Terminology

Pressure switches

Set point

A predetermined value to which a switch is adjusted and at which it performs its intended function.

Reset:

1.

Manual reset: Units with manual reset can only be restored to operational mode by activation of the external
reset button.

2.

Automatic reset: Units with automatic reset is restored to operational mode automatically.

Maximum working pressure

The maximum permissible pressure for safe functioning of a heating system or any of its part.

Snap function

A specic contact force is maintained until snap is initiated. The time over which contact force reaches zero is a few
milliseconds; therefore, contact bounce cannot occur as a result, for example, of slight vibrations before cut-out. The
snap-action contact system will continue to function even when micro-welds are created between the contacts
during cut-in. The force created to separate the contacts is strong, and instantly shears o all contact surface welds

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A

B

C

D

ABCDAdsorption charge

Bellows

Capillary tube

Sensor

Pressure switches and thermostats, Type KP

that have been created as the result of cut-in action. These design features ensure that the cut-out point of the KP
switch remains very accurate and completely independent of the magnitude of the current load.

FLA - Motor Full Load Amperes

FLA is the largest current that a motor or other device is designed to carry at rated voltage and other specic
conditions. Also often called current at rated conditions.

LRA - Locked Rotor Amperes

LRA is the current in amperes drawn by an electric motor with the shaft or rotor immobilized.

Thermostats

Dierential

The dierential is the dierence between the cut-in and cut-out temperatures.
The dierential is necessary for satisfactory automatic operation of the controlled system. Mechanical dierential
(intrinsic dierential). The mechanical dierential is the dierential set by the dierential spindle.

Reset:

1.

Manual reset: Units with manual reset can only be restarted after activation of the reset button. On max reset
units the set value is equal to cut-out value for rising temperature.

2.

Automatic reset: Units with automatic reset is restored to operational mode automatically.

Snap function

A specic contact force is maintained until snap is initiated. The time over which contact force reaches zero is a few
milliseconds; therefore, contact bounce cannot occur as a result, for example, of slight vibrations before cut-out. The
snap-action contact system will continue to function even when micro-welds are created between the contacts
during cut-in. The force created to separate the contacts is strong, and instantly shears o all contact surface welds
that have been created as the result of cut-in action. These design features ensure that the cut-out point of the KP
switch remains very accurate and completely independent of the magnitude of the current load.

FLA - Motor Full Load Amperes

FLA is the largest current that a motor or other device is designed to carry at rated voltage and other specic
conditions. Also often called current at rated conditions.

LRA - Locked Rotor Amperes

LRA is the current in amperes drawn by an electric motor with the shaft or rotor immobilized.

Thermostat charge

Figure 1: Thermostat charge

Sensors with adsorption charges contain a superheated gas together with a solid having a large adsorption surface.
The sensor can be placed in zones that are warmer or colder than the switch housing and capillary tube, but
variations of more than 70 °F may inuence scale accuracy.

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Figure 2: KP 35, KP 36 and KP 37

Figure 3: KP 34

Approximate weight: 0.83 lb

Approximate weight: 0.9 lb

Pressure switches and thermostats, Type KP

Dimensions [in]

Pressure switches

Table 7: Dimensions

Thermostats

Figure 4: KP 79, KP 81

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Type

Range [psig]

Dierential [psi]

Reset

Pressure connec‐

tion

Max. operating

pressure [psig]

Min. burst pres‐

sure [psig]

Code nos

KP 34

2 – 15

2 – 6

Automatic

¼” 18 NPT58435

060-214991

KP 34

2 – 15

3 xed

Manual

¼” 18 NPT58435

060-214891

KP 35

6 – 50

6 – 32

Automatic

¼” 18 NPT

145

1015

060-215191

KP 35

6 – 50

7 xed

Manual

¼” 18 NPT

145

900

060-215091

KP 36

15 – 150

10 – 58

Automatic

¼” 18 NPT

245

1015

060-214491

KP 36

15 – 150

10 xed

Manual

¼” 18 NPT

245

1015

060-214591

KP 37

58 – 300

26 – 45

Automatic

¼” 18 NPT

405

1450

060-214691

KP 37

58 – 300

43 xed

Manual

¼” 18 NPT

405

1450

060-214791

Type

Setting Range [˚F]

Dierential [˚F]

Reset function

Capillary tube

length [in]

Max. sensor temper‐

ature [˚F]

Code nos

KP 79

122 – 210

9 – 27

Automatic

80

300

060L223866

KP 79

122 – 210

10 xed

Manual80300

060L223966

KP 81

176 – 240

9 – 45

Automatic

80

480

060L224066

KP 81

176 – 240

16 xed

Manual80480

060L224166

Part

Symbol

Description

Code no.

Brackets with mounting screws and
washers for pressure switches and
thermostats

Angle bracket
4 screws 10–32 UNC + 4 washers

060-105366

Top cover for pressure switches and
thermostats

When the bracket is mounted on the back plate of the hous­ing, the grade of enclosure of the KP switch is IP44. Top cover
covers the setting spindles.

060-109766

Document type

Approvals Authority

Electrical - Safety

Certicate

CCC

Manufacturer Declaration

EAC

EU Declaration

CE/ LVD

Food and Health - Performance

Certicate

PZH

Marine safety

certicate

RINA

Marine Approval

RMRS

Manufacturer Declaration

RoHS China

Electrical - Safety

Certicate

FM

Electrical - Safety

Certicate

UL

Pressure switches and thermostats, Type KP

Ordering

Pressure switches

Table 8: Ordering

Thermostats

Table 9: Ordering

Table 10: Accessories

Certicates, declarations, and approvals

The list contains all certicates, declarations, and approvals for this product type. Individual code number may have
some or all of these approvals, and certain local approvals may not appear on the list.

Some approvals may change over time. You can check the most current status at danfoss.com or contact your local
Danfoss representative if you have any questions.

Table 11: Certicates, declarations, and approvals

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