Danfoss Electronics RT Data Sheet

Data sheet

Pressure switch RT

RT Pressure switches incorporate a pressure controlled, single-pole change over swich where the contact position depends on the pressure in the connection port and the set value.

The RT series consists of pressure switches, diﬀerential pressure switches and pressure switches for neutral zone regulation, all for general use within the industrial and marine segments. The series also covers safety pressure switches dedicated for steam boiler plants.

For installations in which operation is particularly critical from safety and economic points of view, the use of fail-safe pressure switches is recommended.

The use of gold-plated contacts is also recommended in such installations, provided operation involves only a few switching cycles or signal currents and voltages.

Features • Simple design

• High accuracy

• High repeatability

• Long operation life time

• Available with all major marine approvals

• Safety Integrity Level: SIL 2 according to IEC 61508

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Data sheet | Pressure switch, RT

Approvals

RT 1

RT 1A / RT 121

RT 5A

RT 1AL

RT 5

RT 30AW / RT 30AB / RT 30AS

/ RT 19W / RT 19B / RT 19S

RT 31W / RT 31B / RT 31S /

RT 32W / RT 32B

RT 33B / RT 35W / RT 112W

RT 110

RT 112

RT 113

RT 116 / RT 117 / RT 200

RT 117L / RT 200L

RT 260A/ RT 262A

Approvals

RT 265A / RT 260AL /

RT 262AL / RT 263AL / RT 266AL

• • • • • • • • • • • • • • •

• • •

• • • • • • •

• • • •

• • • • •

• • • • • • • •

• • • • • • • • • • • • • • •

• • • • • • • •

• • • • • • • • • • • • • • •

Note:

in addition we refer to the certiﬁcates, the copies of which can be ordered from Danfoss

Overview/Survey

0 5 10 15 20 25 30

All RT are:

y CE marked in accordance with EN 60947-4/-5 for sale in Europe.

y Further, the RT 19, RT 30, RT 35, RT 112 W, RT 33, RT 31 and RT 32 series is CE marked in accordance

with PED 2014/68/EU, category IV, safety equipment.

CE marked acc. to EN 60947-4/-5

VD TÜV, Germany

Det Norske Veritas and Germanischer Lloyd, DNV GL

Lloyds Register of Shipping, LR

Bureau Veritas, BV

Registro Italiano Navale, RINA

Russian Maritime Register of shipping, RMRS

Nippon Kaiji Kyokai, NKK

China Compulsory Certiﬁcate, CCC

[bar]

Range

pe [bar]

Type

∆p = 0.0 – 0.9 bar ∆p = 0.1 – 1.0 bar ∆p = 0.1 – 1.5 bar ∆p = 0.5 – 4.0 bar ∆p = 0.5 – 6.0 bar ∆p = 1.0 – 6.0 bar

Standard pressure switches

Pressure switches for steam plant

approved by Vd TÜV

Pressure switches with adjustable

neutral zone

Differential pressure switches

-1 – 0

0 – 0.3

0.1 – 1.1

0.2 – 3

-0.8 – 5

0.2 – 6 1 – 10 4 – 17

10 – 30

0.1 – 1.1 0 – 2.5

1 – 10 2 – 10 5 – 25 5 – 25

-0.8 – 5

0.2 – 3

0.2 – 6

4 – 17

10 – 30

-1 – 6

-1 – 9

-1 – 18

-1 – 36

RT 121

RT 113

RT 112

RT 110

RT 1 / RT 1A

RT 200

RT 116

RT 5 / RT 5A

RT 117

RT 112

RT 33B / RT 35W

RT 30AW / RT 30AB / RT 30AS

RT 31W / RT 31B / RT 31S

RT 19W / RT 19B / RT 19S

RT 32W / RT 32B

RT 1 AL

RT 110L

RT 200L

RT 5AL

RT 117L

RT 266AL

RT 263AL

RT 262AL / RT 262A

RT 260AL / RT 260A

RT 260A

RT 265A

IC.PD.P10.6B.02 | 520B8146 | 2

Data sheet | Pressure switch, RT

Technical data and code nos.

RT 113

for manual setting; cover with windows

RT 116 for tamper proof; cap and blank cover

When ordering, please state type and code number.

The type designation for the letters below means:

A: Unit suitable for ammonia L: Unit with neutral zone

Pressure switches

Regulation

range

Adjustable/

ﬁxed

mechanical

diﬀerential

[bar] [bar] [bar] [bar]

-1 – 0 0.09 – 0.4 7 8 G 3/8 A

0 – 0.3 0.01 – 0.05 0.4 0.5 G 3/8 A

0.1 – 1.1

0.07 – 0.16

0.1 – 1.1 0.07 7 8 G 3/8 A

0.2 – 3

0.08 – 0.25

0.08

-0.8 – 5 0.5 – 1.6 22 25 /-20 UNF

-0.8 – 5 0.5 22 25 /-20 UNF

-0.8 – 5 0.5 – 1.6 22 25 G 3/8 A 1)

-0.8 – 5 0.5 22 25 G 3/8 A 1)

-0.8 – 5

1.3 – 2.4

0.2 – 6 0.25 – 1.2 22 25 G 3/8 A

0.2 – 6 0.25 22 25 G 3/8 A 1 – 10 0.33 – 1.30 22 25 G 3/8 A 1 – 10 0.33 22 25 G 3/8 A 4 – 17

1.2 – 4 4 – 17 1.2 – 4 22 25 G 3/8 A 4 – 17

1.2 4 – 17 1.2 – 4 22 25 G 3/8 A 1) 4 – 17

1.3

10 – 30 1 – 4 42 47 G 3/8 A

) Supplied with ø6 / ø10 mm weld nipple.

) With seal cap.

Max. working pressure

Max.

test

pressure

Pressure

connection

ISO 228/1

7 8 G 3/8 A

7 8 G 3/8 A 7 8 G 3/8 A

22 25 G 3/8 A 1)

017-521566 – – –

017-519666 – – –

017-519166 – – 017-519366

– 017-519266 – –

017-529166 – – 017-529266

– – 017-511066 –

017-524566 – – –

– – 017-524666 –

017-500166 – – –

– – 017-500266 –

017-500766 – – –

017-523766 – – 017-524066

– 017-523866 017-523966 –

017-520366 017-520066

– 017-520466 017-519966 –

017-525566 – – –

– – – 017-525366

– 017-5094662) – –

017-5046662) – – –

– 017-5047662) – –

017-529566 – – 017-529666

Pressure switches with adjustable neutral zone

Regulation

range

[bar] [bar] [bar] [bar] [bar]

Mechanical diﬀerential

Adjustable

neutral zone

Max.

working

pressure. PS

-0.8 – 5 0.2 0.2 – 0.9 22 25 G 3/8 A 1)

0.2 – 3 0.08 0.08 – 0.2 7 8 G 3/8 A

0.2 – 6 0.25 0.25 – 0.7 22 25 G 3/8 A 4 – 17 0.35 0.35 – 1.4 22 25 G 3/8 A 1)

10 – 30 1 1 – 3.0 42 47 G 3/8 A

) Supplied with ø6 / ø10 mm weld nipple.

Max. test pressure

Code no.

Pressure

connection

Code no. Type

017L003366

017L001566

017L003266

017L004066

017L004266

Type

RT 121 RT 113 RT 112 RT 112 RT 110 RT 110 RT 1 RT 1 RT 1A RT 1A RT 1A RT 200 RT 200 RT 116 RT 116 RT 5 RT 5 RT 5 RT 5A RT 5A RT 117

RT 1AL

RT 110L

RT 200L

RT 5AL

RT 117L

RT 262 A Diﬀerential pressure switch

Preferred versions

Diﬀerential pressure switches

Regulation range (Δp)

[bar] [bar] [bar] [bar] [bar] [bar]

Mechanical diﬀerential

Adjustable

neutral

zone

0 – 0.9 0.05 0.05 – 0.23 -1 – 6 7 8 G 3/8 A 1) 017D008166 RT 266AL

0.1 – 1.0 0.05 0.05 – 0.23 -1 – 6 7 8 G 3/8 A 1) 017D004566 RT 263AL

0.1 – 1.5 0.1 0.1 – 0.33 -1 – 9 11 13 G 3/8 A 1) 017D004366 RT 262AL

0.1 – 1.5 0.1  -1 – 9 11 13 G 3/8 A 1) 017D002566 RT 262A 0 – 0.3 0.035 – -1 – 10 11 13 G 3/8 A 1) 017D002766

0.5 – 4 0.3 0.3 – 0.9 -1 – 18 22 25 G 3/8 A 1) 017D004866 RT 260AL

0.5 – 4 0.3 – -1 – 18 22 25 G 3/8 A 1) 017D002166 RT 260A

0.5 – 6 0.5 – -1 – 36 42 47 G 3/8 A 1) 017D002366 RT 260A

1.5 –11 0.5 – -1 – 31 42 47 G 3/8 A 1) 017D002466 RT 260A 1 – 6 0.5 – -1 – 36 42 47 G 3/8 A 1) 017D007266

Supplied with ø6 / ø10 mm nipple. / 2) Non-snap action contacts (see spare parts and accessories, contact system 017-018166).

With SPST and SPDT contact system for alarm and cut oﬀ function at 0.8 and 1 bar.

Operation

range for LP

bellows

Max.

working

pressure. PS

Max. test pressure

Pressure

connection

ISO 228/1

Code no. Type

) RT 262A

) RT 265A

IC.PD.P10.6B.02 | 520B8146 | 3

Data sheet | Pressure switch, RT

Technical data and ordering

The designation letters mean:

A: Units suitable for ammonia.

W: Units for control purposes.

B: Safety units with external reset

S: Safety units with internal reset

Pressure switches for steam plant, PED approved acc. to EN 12953-9 and EN 12922-11

Code no.

Regulation

range

Adjustable/

ﬁxed

mechanical

diﬀerential

Max. working pressure

Max.

test

pressure

Pressure

connection

ISO 228/1

[bar] [bar] [bar] [bar]

For rising pressure

0.1 – 1.1 0.07 7 8 G ½ A 0 – 2.5 0.1 7 8 G ½ A

1 – 10 0.8 22 25 G ½ A 1 – 10 0.6 22 25 G ½ A 1 – 10 0.4 22 25 G ½ A 5 – 25 1.2 42 47 G ½ A 5 – 25 1 42 47 G ½ A 5 – 25 1 42 47 G ½ A

017-528266

017-528066

017-518766

–

017-518166

–

– –

017-518866

017-518966

– –

017-518266

017-518366

For falling pressure

0 – 2.5 0.1 7 8 G ½ A

2 – 10 0.3 – 1 22 25 G ½ A 2 – 10 0.3 22 25 G ½ A 2 – 10 0.3 22 25 G ½ A 5 – 25 0.8 – 3 42 47 G ½ A 5 – 25 0.4 42 47 G ½ A

– –

017-526766

– –

017-524766

– –

Pressure switches for low pressure steam plant (pressure monitoring)- not PED approved

0.1 – 1.1 0.07 – 0.16 7 7 G ½ A

017-518466

– –

–

017-526266

017-526866

017-526966

017-524866

Type

RT 112W

RT 35W

RT 30AW

RT 30AB

RT 30AS

RT 19W

RT 19B

RT 19S

RT 33B

RT 31W

RT 31B

RT 31S

RT 32W

RT 32B

RT 112

Preferred versions

Technical data

Designation RT pressure switches

In general -50 – 70 °C

Ambient temperature

Diaphragm version -10 – 70 °C VD TÜV approved -40 – 70 °C

In general -50 – 100 °C

Media temperature

Diaphragm version -10 – 90 °C VD TÜV appr. -40 – 150 °C, see page 6 (Steam plant)

Contact system

Single-pole changeover switch (SPDT)

Alternating current:

Contact load

AC-1: 10A, 400 V AC-3: 4A, 400 V AC-15: 3A, 400 V

Contact material: AgCdO

Direct current:

DC-13: 12 W, 220 V (see ﬁg. 6)

Fig. 6

Special contact system See “accessories” page 15

Cable entry 2 PG 13.5 for 6 – 14 mm diameter cables

Solid / stranded 0.2 – 2.5 mm

Flexible, without ferrules 0.2 – 2.5 mm

Flexible, with ferrules 0.2 – 1.5 mm

Tightening torque max. 1.5 Nm

IP66 acc. to IEC 529 and EN 60529. Units supplied with external reset.

Enclosure

IP54. The thermostat housing is made of bakelite acc. to DIN 53470 Cover is made of polyamide.

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Data sheet | Pressure switch, RT

Materials in contact with the medium

Material Part W .no. DIN

RT 1

RT 1A

RT 5

RT 5A

RT 110

RT 112

RT 113

RT 116

RT 117

RT 121

RT 200 / RT 200L

RT 260A

RT 260A / 262A / RT 262AL

RT 260AL

Stainless steel 18/8 Bellows 1.4306 17440 x x x x x x x x x x x x x x x

Stainless steel 17/7 Spring 1.4568 17224 x x x x x

Brass Housing 2.0402 17660 x x x x x x x

Brass Bellows ring 2.0321 17660 x x x x x x x

Free-cutting steel Flare connection 1.0718 1651 x

RT 265A

RT 263AL / RT 266AL

Deep-drawn steel (nick.plated surface)

Non-alli. carbon steel C 20

Aluminium Gasket 3.0255 1712 x x x x x x x x

NBR rubber Diaphragm x

Deep-drawn steel (surface DIN 50961 weld connection Fe/Zn 5C)

Spring thread Spring 1.1250 17223 x

Housing 1.0338 1623 x x x x x x x x

Weld connect. for connection

Diaphragm housing with welded connector

1.0402 1652 x x x x x x x

1.0338 1623 x

Materials in contact with the medium, PED approved switches

Material Part W .no. DIN

RT 19W / RT

19B / RT 19S

Stainless steel 18/8 Bellows 1.4301 17440 x x x x x x

Stainless steel 17/7 Oriﬁce 1.4305 17440 x x

/ RT

RT 30AW / RT 30AB

30AS

RT 31W / RT

31B / RT 31S

RT 32WB

RT 33B / RT

35W

RT 112 W

Steel C 15 Connector 1.0401 1652 x x

Deep-drawn steel + Ni Bellows ring 1.0338 1623 x x x x x x

Stainless steel 17/7 Bellows spring 1.4568 17224 x x

Stainless steel Ring 1.4305 17440 x

Deep-drawn steel + Ni Housing 1.0338 1623 x x x x x x

Stainless steel Bellows connect. 1.4305 17440 x

Stainless, weldable freecutting steel

Deep-drawn steel + Sn Spring guide 1.0338 1623 x

Brass Housing 2.0402 17660

Brass Bellows ring 2.0321 17660

Connector 1.4301 17440 x x x x

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Data sheet | Pressure switch, RT

Function

Scale setting −−−− Mechanical diﬀerential

Fig. 4. Contact function, setting for rising pressure.

a. RT 19, RT 30 and pressure switches with max. reset

When the pressure exceeds the set range value, contacts 1-4 make and contact 1-2 brake. The contacts changeover to their initial position when the pressure falls to the range value minus the diﬀerential (see ﬁg. 4).

Scale setting −−−− Mechanical diﬀerential

I.Alarm for rising pressure given

at the set range value.

II. Alarm for falling pressure given at the set

range value minus the diﬀerential.

Units with max. reset can only be reset at a pressure corresponding to the set range value minus the diﬀerential, or a lower pressure.

Fig. 5. Contact function, setting for falling pressure.

b. All other RT pressure switches

When the pressure falls to the set range value, contacts 1-2 make and contacts 1-4 brake. The contacts changeover to their original position when the pressure again rises to the set range plus the diﬀerential (see ﬁg. 5).

I. Alarm for falling pressure given at the set range value.

II. Alarm for rising pressure given at the set

range value plus the diﬀerential.

Units with min. reset can only be reset at a pressure corresponding to the set range value plus the diﬀerential.

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Data sheet | Pressure switch, RT

Function

(continuation)

Functional description of RT units with fail-safe design

Example 1

An extra cooling water pump must start if the cooling water pressure falls below 6 bar, and must stop when the pressure exceeds 7 bar.

Choose an RT 116 with a range of 1 – 10 bar and an adjustable diﬀerential of 0.2 – 1.3 bar.

The start pressure of 6 bar must be set on the range scale. The diﬀerential must be set as the diﬀerence between the stop pressure (7 bar) and the start pressure (6 bar) = 1 bar. According to ﬁg. 3, the diﬀerential setting disc must be set on 8.

Example 2

The burner on a steam boiler must cut out when the pressure exceeds 17 bar. Automatic restart must not occur.

Choose an RT 19B with external reset. If extra safety is demanded, an RT 19S with internal max. reset can be used.

The range is 5 – 25 bar and the diﬀerential is ﬁxed at approx. 1 bar. The range scale must be set at 17 bar. After cut-out of the burner, manual reset is possible only when the pressure had fallen to the setting of 17 bar minus the diﬀerential: in this case, 16 bar and below.

Example 3

The min. permissible lubricating oil pressure for a gear is 3 bar. Reset must not be possible until the reason for oil pressure failure has been investigated. Choose an RT 200 with min. reset.

The range value must be set while reading the range scale. Manual reset is possible only when the pressure has reached 3.2 bar (the diﬀerential is ﬁxed at 0.2 bar or higher).

Fail-safe function for falling pressure

Fig. 5a shows a cross-section of a bellows element for the RT 32W with fail-safe function for falling pressure. On rising pressure the contact arm is actuated to break the connection between terminals 1 and 2.

On falling pressure the contact arm is actuated to break the connection between terminals 1 and 4. If a defect occurs in the bellows the setting spring actuates the contact arm to break the connection between terminals 1 and 4, as in the case of falling pressure. This will occur irrespective of the pressure on the bellows.

Fig. 5a

Fig. 5b

Fail-safe function for rising pressure

Fig. 5b shows a cross-section through a bellows element for the RT 30W with fail-safe for rising pressure. On rising pressure the contact arm is actuated to break the connection between terminals 1 and 2 .

If a defect occurs in the inner bellows the pressure is led to the outer bellows. The outer bellows has an area three times as large as the inner bellows. The connection between terminals 1 and 2 becomes broken.

If a defect occurs in the outer bellows, there will be atmospheric pressure in the gap between the two bellows. This actuates the contact system to break the connection between terminals 1 and

2. The important factor with the double bellows design is the vacuum between the two bellows. and that in case of bellows break, no media will leak into the environment.

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Data sheet | Pressure switch, RT

Pressure switches for liquid level control RT 113

The RT 113 pressure switch can be used to control the liquid level in open tanks. Fig. 6 shows in principle, four diﬀerent types of installation.

1. With air bell (see “Accessories”)

For control purpose, the air bell should be installed 20 – 40 mm below the lowest liquid level. In addition, the tube between the RT 113 and the air bell must be absolutely airtight. If only an indication is required, the bell can be placed 100 mm below the max. level. The RT 113 must be set at 0 cm wg and the diﬀerential disc on 1.

2. Connection to the side of the tank with the RT 113 above the liquid level

The horizontal tube A must have a certain length in relation to the vertical tube B in order to ensure reliable control. The length ofA can be found from ﬁg. 7, using B and the range setting pressure C.

3. Connection to the side of the tank with the RT 113 below the liquid level

Where possible, this form of connection should be used. If an air-absorbing liquid like oil is involved, it is preferable to 1 and 2. The resulting range setting is the distance from the liquid surface to the centre of the diaphragm housing.

4. Connection in the tank with the RT 113 above the liquid level

This method is for use with air-absorbing liquids where connection type 3 is not possible. The shortest horizontal tube length is determined as described in 2. A shut-oﬀ valve is installed between the oil tank and water reservoir shown so that impurities can be drained from the water reservoir through a bottom drain plug. Fresh water can then be poured into the reservoir through a ﬁlling connector in its top.



Fig. 6 Fig. 7

Height from tank connector to pressure switch

Min. horizontal tube length

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Data sheet | Pressure switch, RT

Application

5. Setting knob

9. Range scale

40. Neutral zone disc

Fig. 8

RT-L pressure switches are ﬁtted with a switch with an adjustable neutral zone. This enables the units to be used for ﬂoating control. The terminology involved is explained below.

Floating control

A form of discontinuous control where the correcting element (e.g. valve, damper, or similar) moves towards one extreme position at a rate independent of the magnitude of the error when the error exceeds a deﬁnit positive value, and towards the opposite extreme position when the error exceeds a deﬁnite negative value.

Hunting

Periodic variations of the controlled variable from the ﬁxed reference.

Neutral zone

The interval in the controlled variable in which the correcting element does not respond (see ﬁg. 13)

The contact system in neutral zone units cannot be exchanged, as the contact system adjustment is adjusted to the other parts of the unit.

Setting of neutral zone The range is set using the setting knob (5) ﬁg. 8

while reading the range scale (9). The pressure set is the break pressure for contacts 1-4 (see ﬁg. 13).

NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE

RANGE

POSITION

Fig. 9 Fig. 10 Fig. 11

RANGE

The required neutral zone can be found in the diagram for the unit concerned. The position at which the neutral zone disc (40) must be set can be read from the lower scale in the diagram. The function can be seen in ﬁg. 13.

DIFF. RANGE

POSITION

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Data sheet | Pressure switch, RT

Setting of neutral zone

NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE

RANGE

Fig. 12 Fig. 13

Pressure gauge

POSITION POSITION

Range setting

Inlet pressure

Differential (mechanical differential) corresponds to the least neutral zone setting.

The neutral zone. Inlet pressure may vary within this interval without resulting in a make function 1-2 or 1-4.

RANGE

Example

Together with a VLT® static frequency converter, RT 200L neutral zone pressure switches can be used for the inﬁnite control of a pump in, for example, a pressure boosting plant.

In this case, the pump must be up and downregulated at 32 m and 25 m wg.

The RT 200L must be set using the setting knob (5) ﬁg. 8 page 9 at 3.5 bar (35 m wg) minus the ﬁxed diﬀerential of 0.2 bar.

Compressed air

Signal lamp for falling and rising pressure

Fig. 14. Test setup for setting the pressure switch.

The range setting is 3.5 - 0.2 = 3.3 bar.

The neutral zone, 35 - 32 = 3 m wg, corresponding to 0.3 bar, must be set on the neutral zone disc (40) ﬁg. 8 page 9. According to the diagram ﬁg. 12 the disc setting is 1 or just over. A more accurate setting can be obtained by using the test setup shown in ﬁg. 14.

IC.PD.P10.6B.02 | 520B8146 | 10

Data sheet | Pressure switch, RT

Application Control and monitoring of pressure diﬀerentials

A diﬀerential pressure switch is a pressure controlled switch that cuts in and cuts out the current dependent on the pressure diﬀerential between the counteracting bellows

Setting

elements and the set scale value. This unit is also available with an adjustable neutral zone (like the RT-L which is described on page 9.

The setting disc (5) becomes accessible when the front cover is removed. The diﬀerential pressure is set by turning the disc with a screwdriver while reading the scale (9).

For diﬀerential pressure switches with a changeover contact system, the contact diﬀerential is given as the diﬀerential pressure switches have a ﬁxed diﬀerential. In units with an adjustable neutral zone, the neutral zone disc must also be set. See diagram in ﬁg. 16.

Note:

5. Setting disc

9. Range scale

NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE NZ = NATURALZONE / DEADZONE

DIFF RANGE

POSITION

Fig. 16

Fig. 15

DIFF RANGE DIFF RANGE DIFF RANGE

When installing, the low pressure connection (LP) must always be upwards

POSITIONPOSITIONPOSITIONPOSITION

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Data sheet | Pressure switch, RT

Function

Scale setting −−−− Mechanical diﬀerential

Fig. 17. Contact function, setting of falling diﬀerential pressure.

a. Units with changeover switch (SPDT)

If the diﬀerential pressure falls below the set value, contacts 1-2 make and contacts 1-4 break. Contacts 1-2 break again and contacts 1-4 make when the diﬀerential pressure has risen to the set range value plus the ﬁxed contact diﬀerential.

Range setting Inlet pressure

Mechanical differential

Differential (mechanical differential) corresponds to the least neutral zone setting.

The neutral zone and inlet differential pressure may vary within this interval without resulting in a make function 1-2 or 1-4.

Fig. 18. Contact function, setting of neutral zone.

b. Units with adjustable neutral zone (SPDTNP)

If the diﬀerential pressure rises above the set value plus the diﬀerential, contacts 1-4 make. If the pressure falls by the amount of the diﬀerential (which is ﬁxed in this unit), contacts 1-4 break. If the pressure falls to the neutral zone minus the diﬀerential, contacts 1-2 make. When the diﬀerential pressure rises again by an amount corresponding to the diﬀerential, contacts 1-2 break again.

I. Contacts make when diﬀerential pressure

falls below the range scale setting.

II. Contacts make when pressure rises above

the range scale setting plus the ﬁxed mechanical diﬀerential.

The contact function can be summed up as follows:

I. Setting disc set for falling diﬀerential pressure.

II. Neutral zone disc set for rising diﬀerential

pressure.

Example 1

When the diﬀerential pressure exceeds 1.3 bar, a ﬁlter needs cleaning. The static pressure over the ﬁlter is 10 bar.

According to the ordering table on page 4, the choice is an RT 260A (the RT 262A has a max. operating pressure on the low pressure side (LP) of 9 bar and is therefore not suitable for this application).

Setting: Since a signal is required for rising diﬀerential pressure, the setting becomes

1.3 - 0.3 bar = 1.0 bar.

Example 2

The speed of a circulation pump must be controlled to give a constant diﬀerential pressure of 10 m wg in a heating plant. The static plant pressure is 4 bar. The choice is an RT 262AL.

The diﬀerential disc (5) ﬁg. 15 page 13, must be set at 1 bar (10 m wg) minus the ﬁxed diﬀerential of 0.1 bar, i.e. 0.9 bar. The neutral zone disc is factory-set (marked in red).

IC.PD.P10.6B.02 | 520B8146 | 12

Danfoss

17-660-15

Danfoss

17-660-15

Data sheet | Pressure switch, RT

Dimensions [mm] and weights [kg]

RT 13

RT 5, RT 110, RT 112, RT 116, RT 117 / RT 117L, RT 121, RT 200 / RT 200L

RT 5, RT 110, RT 112, RT 116, RT 117, RT 200

Special version with tamper proof

cap and blank cover

RT 5 RT 1A / RT 1AL

RT 260A / RT 260AL

: External reset knob only for RT...B

RT 262A / RT 262A /

RT 263AL

RT 5 RT 5A / RT 5AL

Danfoss

17-660-15

Weight: approx. 1 kg

RT 30AW / RT 30B / RT 30S L = 225

RT 19W / RT 19B / RT 19S L = 228

RT 33B / RT 35W L = 221

RT 112W L = 210

RT 31W / RT 31B / RT 31S L = 212

RT 32W / RT 32B L = 212

IC.PD.P10.6B.02 | 520B8146 | 13

Data sheet | Pressure switch, RT

Spare parts and accessories

Version Symbol Description Contact rating Code no.

Single-pole changeover switch (SPDT) with

Standard

With max. reset

With min. reset

terminal board proof against leakate current

Fitted in all standard versions of type RT1).

Snap action changeover contacts.

For manual reset of unit after contact changeover on rising pressure

For units with max. reset.

For manual reset of units after contact changeover on falling pressure.

For units with min. reset.

Alternating current:

AC-1 (ohmic): 10 A, 400 V AC-3 (inductive): 4 A, 400 V AC-15: 3 A, 400 V Blocked rotor: 28 A, 400 V

Direct current:

DC-13: 12 W, 220 V

017-403066

017-404266

017-404166

Single-pole changeover switch (SPDT) with gold plated (oxide-free) contact surfaces.

Standard

Increases cut-in reliability on alarm and monitoring systems, etc. Snap action changeover contacts. Terminal board proof against leakage current.

Single-pole changeover switch that cuts in two

Cuts in two circuits simultaneously

circuits simultaneously on rising pressure. Snap action changeover contacts. Terminal board proof against leakage current.

With non-snap action changeover contacts

) At load types with low currents/voltages contact failure may

occure on the silver contacts because of oxidation. In systems where such a contact failure is of great importance (alarm etc.), gold plated contacts are recommended.

Contact systems for neutral zone units are not available as spare parts. Exchange not possible, as the contact system adjustment is adjusted to the other parts of the unit.

Single-pole changeover with non-snap action changeover gold plated (oxide-free) contacts.

Alternating current

AC-1 (ohmic): 10 A, 400 V AC-3 (inductive): 2 A, 400 V AC-15: 1 A, 400 V Blocked rotor: 14 A, 400 V

017-424066

Direct current:

DC-13: 12 W, 220 V

Alternating current:

AC-1(ohmic): 10 A, 400 V AC-3 (inductive): 3 A, 400 V AC-15: 2 A, 400 V Blocked rotor: 21 A, 400 V

Direct current:

017-403466

DC-13: 12 W, 220 V

* If current is led through contacts 2 and 4,

i.e. terminals 2 and 4 connected but not 1, max. permissible load is increased to 90 W, 220 V - - -.

Alternating or direct current:

25 VA, 24 V

017-018166

The switch contacts are shown in the position they assume on falling pressure/temperature, i.e. after downward movement of the RT main spindle. The setting pointer of the control shows the scale value at which contact changeover occurs on falling pressure/temperature. An exception is switch no. 017-403066 with max. reset where the setting pointer shows the scale value at which contact changeover occurs on rising pressure.

Switches

Version Symbol Description Contact rating Code no.

For Alarm application

Alternating current:

AC-1 (ohmic): 10 A, 400 V AC-3 (inductive): 2 A, 400 V Full load current: 2 A, 400 V AC-15: 1 A, 400 V Blocked rotor: 14A, 400 V

Direct current

DC-13: 12W, 220 V

For control application

max. 100 mA / 30 V CA / CC mini. 1 mA / 5 V CA / CC

IC.PD.P10.6B.02 | 520B8146 | 14

017-404766

017-404866

With min. manual reset

With max. reset

For manual reset of unit after contact changeover on falling pressure.

Gold plated (oxide-free) contact surfaces

For manual reset of unit after contact ochangeover on rising pressure.

Gold plated (oxide-free) contact surfaces

Data sheet | Pressure switch, RT

Part Description Qty.. Code no.

Cover

Covers: Polyamide With window Colour: Pale grey RAL 7035 Without window

5 5

017-436166 017-436266

Setting knob Replacement Pale grey Ral 7035 30 017-436366

Seal cap

Seal cap to replace setting knob so that Black Setting can only be altered with tools

20 017-436066

Seal screws for cover and

1+1 017-425166

seal cap

Clamping band

Conncetor with nipple

For all RT pressure switches with damping c oil or other longer connections L= 392 mm

Pipe thread ISO 228/1, G

connector, nipple and AL

washer (10 mm ext. 6.5 mm int. diam.) for welding or brazing on to steel or copper tubing

10 017-420466

5 017-436866

Connector 7/16 - 20 UNF connector for ¼ copper tube, brass, span of jaws 16 10 011L1101

Reducer Pipe thread ISO 228/1, G ½ A × G

, steel, span of jaws 22 1 017-421966

Adaptor

Pipe thread ISO 228/1, G brass, span of jaws 22

Adaptor Pipe thread ISO 228/1, G

Damping coil

Armoured damping coil

0.50 m

1.00 m

1.50 m

2.00 m

Damping coil with 7/16 - 20 UNF connectors. Reducer code no. 017-420566 is necessary if the damping coil is to be used with RT units having a pipe thread ISO 228/1, G several lengths of capillary tubes are available. Please contact Danfoss.

Pipe thread ISO 228/1, damping coils with G copper capillary tube. Standard washers are supplied.

Pipe thread ISO 228/1, damping coil with G copper capillary tube. Standard washers are supplied.

- 27 NPT with copper washer,

A × ¼ - 18 NPT with copper washer,

× ¼ - 18 NPT with copper washer,

A - G ¼ A, brass, span of jaws 17 1 060-324066

A × R3/8 (ISO 7/1) brass, span of jaws 17 1 060-324166

1 060-333466

1 060-333566

1 060-333666

060-019066 060-019166

connection. Damping coils with

060-019266 060-019366

connector and 1.5 m

connector and 1 m

1 060-104766

1 060-333366

Air bell for liquid level control RT 113

Air bell, 62 mm diam. ext. × 204 mm length. Pipe thread ISO 228/1,

connector and nipple (10 mm o.d./ 6.5 mm i.d.) for welding or

brazing on to steel or copper tubing. The air bell is of brass CuZn 37, W.no. 2.0321.

1 017-401366

IC.PD.P10.6B.02 | 520B8146 | 15

Data sheet | Pressure switch, RT

Installation

RT units have two mounting holes which become accessible when the front cover is removed. Units ﬁtted with switch 017-018166 *) must be installed with the setting knob upwards. When installing diﬀerential pressure switches, the low pressure side (marked LP) must be installed upwards. The other pressure switches in the RT series can be installed in any position, expect that on plant subjected to severe vibrations it is advantageous to have the screwed cable entry downwards.

*) Contact system with snap-action contact. See spare parts and accessories, page 13.

Fig. 1. Positioning of unit.

Pressure connection

When ﬁtting or removing pressure lines, the spanner ﬂats on the pressure connection should be used to apply counter-torque.

Steam plant

To protect the pressure element against temperature in excess to the maximum temperature of the medium 150 °C (RT 113 90 °C), the insertion of water-ﬁlled loop is recommended.

Water systems

Water in the pressure element is not harmful, but if frost is likely to occur a water-ﬁlled pressure element may burst. To prevent this happening, the pressure control can be allowed to operate on an air cushion.

Media resistance

See table of materials in contact with the medium. If seawater is involved, diaphragm pressure switches types KPS 43, KPS 45 and KPS 47 are recommended.

Pulsations

The pressure switch must be connected in such a way that the pressure element is aﬀected by pulsations as little as possible. A damping coil can be inserted (see “Accessories”). With strongly pulsating media, diaphragm pressure switches types KPS 43, KPS 45 and KPS 47 can be advantageous.

Setting

The range is set by using the setting knob (5) while at the same time reading the scale (9). Tools must be used to set pressure switches ﬁtted with a seal cap.

In units having a ﬁxed diﬀerential, the diﬀerence between cut-in and cut-out pressures is of course determined. On units having an adjustable diﬀerential the front cover must be removed. The diﬀerential disc (19) must be set in accordance with the diaphragm.

5. Setting knob

9. Range scale

19. Diﬀerential setting disc

Fig. 2

IC.PD.P10.6B.02 | 520B8146 | 16

Installation

Selection of diﬀerential

To ensure that the plant functions properly, a suitable diﬀerential pressure is necessary. Too small a diﬀerential will give rise to short running periods with a risk of hunting. Too high a diﬀerential will result in large pressure oscillations.

Diﬀerential scale values are guiding.

Fig. 3. Obtainable diﬀerential disc scale.

Danfoss Electronics RT Data Sheet

Specifications and Main Features

Frequently Asked Questions

User Manual