Pressure switches and thermostats, type KP

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AI209986438809en-000602

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 fitted 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 fitted 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

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
Key sketch of KP pressure switch

Simplified drawing of KP pressure switch without front cover and scale. Version with manual reset.

1 Range setting spindle 2 Differential setting spindle 3 Main arm 4 Main spring 5 Differential spring

6 Bellows 7 Pressure connector 8 Contact system 9 Switch terminals 10 Ground terminal

11 Cable entry: ½ in female NPSM 12 Tumbler 13 Locking screw 14 Manual reset 15 Distance plate

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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Pressure switches and thermostats, Type KP
Thermostats
Table 2: Design and function
Key sketch of KP 79, KP 81 thermostats

Simplified drawing of KP thermostat without front cover and scale. Version with manual reset.

1 Range setting spindle 2 Differential setting spindle 3 Main arm 4 Main spring 5 Differential spring 6 Bellows

7 Temperature sensors 8 Contact system 9 Terminals 10 Ground terminal 11 Cable entry: ½ in female cable
gland

12 Tumbler 13 Locking screw 14 Manual reset 15 Distance plate

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Pressure switches and thermostats, Type KP

Product specification

Technical data

Pressure switches

Table 3: Technical data
Features Ambient temperature Media temperature Sensor material Parts in contact with medium:

Wire dimension Contact system

Contact load

Alternating current

Enclosure Cable entry

Direct current

Bellows: Pressure connection:
FLA LRA

Descriptions -40 150 °F (175 °F for short period of time) -40 212 °F Tinned copper Cu/Sn5 Stainless steel Free-cutting steel, nickel plated 12 AWG max. SPST (close on temp. rise), SPDT Contact material AgCdO 0.5 ~ 16 A/120 V AC 0.5 ~ 8 A/240 V AC 96 A/120 V AC 48 A/240 V AC 240 V DC: 12 W pilot duty NEMA ~1 (when mounted on a flat surface with all unused holes covered) Integral ½ in female NPSM swivel cable connector, allows direct attachenments of ½ in. male pipe thread connector

Thermostats

Table 4: Technical data

Features

Ambient temperature

Sensor material

Wire dimension

Contact system

Contact load

Alternating current FLA

LRA

Enclosure Cable entry

Direct current

Descriptions -40 150 °F (175 °F for short period of time) Tinned copper Cu/Sn5 12 AWG max. SPDT single pole double throw 0.5 ~ 16 A/120 V AC 0.5 ~ 8 A/240 V AC
96 A/120 V AC 48 A/240 V AC 240 V DC: 12 W pilot duty NEMA ~1 (when mounted on a flat surface with all unused holes covered) Integral ½ in female NPSM swivel cable connector, allows direct attachenments of ½ in. male pipe thread connector

Contact system and application

Pressure switches

Table 5: Contact system and application
Switch type - single pole double throw Switch action Terminals 1 4 close high and open low Terminals 1 2 can be used as low pressure alarm
Terminals 1 2 open high and close low Terminals 1 4 can be used as high pressure alarm

Application Low pressure cut-out
High pressure cut-out

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Pressure switches and thermostats, Type KP

Thermostats
Table 6: Contact system and application
Switch type - single pole double throw Switch action Terminals 1 4 close high and open low Terminals 1 2 can be used as low temperature alarm
Terminals 1 2 open high and close low Terminals 1 4 can be used as high temperature alarm

Application Low pressure cut-out
High pressure cut-out

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 differential on DIFF scale. NOTE: Restart pressure is equal to cut-out pressure minus differential 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 fixed value of the differential.
Thermostats
Thermostats with automatic reset Set the cut-out temperature on the RANGE scale and differential on the DIFF scale. Restart temperature is equal to the cut-out temperature minus differential value. NOTE: The differential 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 differential scale as a guide, and if precise function is required, establish the differential 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 differential is fixed. 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 fixed differential.
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 specific 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 off all contact surface welds

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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 specific 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

Differential The differential is the difference between the cut-in and cut-out temperatures. The differential is necessary for satisfactory automatic operation of the controlled system. Mechanical differential (intrinsic differential). The mechanical differential is the differential set by the differential 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 specific 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 off 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.

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

A Adsorption charge

B Bellows

C Capillary tube

B D Sensor

D 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 influence scale accuracy.

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Pressure switches and thermostats, Type KP
Dimensions [in] Pressure switches
Table 7: Dimensions
Figure 2: KP 35, KP 36 and KP 37

Figure 3: KP 34

Approximate weight: 0.83 lb
Thermostats
Figure 4: KP 79, KP 81

Approximate weight: 0.9 lb

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Pressure switches and thermostats, Type KP

Ordering

Pressure switches

Table 8: Ordering

Type

Range [psig]

KP 34 KP 34 KP 35 KP 35 KP 36 KP 36 KP 37 KP 37

2 15 2 15 6 50 6 50 15 150 15 150 58 300 58 300

Differential [psi]
2 6 3 fixed 6 32 7 fixed 10 58 10 fixed 26 45 43 fixed

Reset
Automatic Manual
Automatic Manual
Automatic Manual
Automatic Manual

Pressure connec- tion
¼" 18 NPT ¼" 18 NPT ¼" 18 NPT ¼" 18 NPT ¼" 18 NPT ¼" 18 NPT ¼" 18 NPT ¼" 18 NPT

Max. operating pressure [psig]
58 58 145 145 245 245 405 405

Min. burst pres- sure [psig] 435 435 1015 900 1015 1015 1450 1450

Code nos
060-214991 060-214891 060-215191 060-215091 060-214491 060-214591 060-214691 060-214791

Thermostats

Table 9: Ordering

Type

Setting Range [°F]

KP 79 KP 79 KP 81 KP 81

122 210 122 210 176 240 176 240

Differential [°F]
9 27 10 fixed 9 45 16 fixed

Reset function
Automatic Manual
Automatic Manual

Capillary tube length [in] 80 80 80 80

Max. sensor temper- ature [°F] 300 300 480 480

Code nos
060L223866 060L223966 060L224066 060L224166

Table 10: Accessories
Part

Symbol

Description

Code no.

Brackets with mounting screws and washers for pressure switches and thermostats

Angle bracket 4 screws 1032 UNC + 4 washers

060-105366

Top cover for pressure switches and thermostats
Certificates, declarations, and approvals

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

The list contains all certificates, 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: Certificates, declarations, and approvals
Document type Electrical - Safety Certificate Manufacturer Declaration EU Declaration Food and Health - Performance Certificate Marine safety certificate Marine Approval Manufacturer Declaration Electrical - Safety Certificate Electrical - Safety Certificate

Approvals Authority CCC EAC CE/ LVD PZH RINA RMRS RoHS China FM UL

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