Pressure switch RT
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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. • Simple design • High accuracy • High repeatability • Long operation life time • Available with all major marine approvals

Note: in addition we refer to the certificates, the copies of which can be ordered from Danfoss All RT are: • CE marked in accordance with EN 60947-4/-5 for sale in Europe • Further, the RT 19 , RT 30, RT 35, RT 112 W, RT 33, RT 31 and RT 32 series is CE markd in accordance with PED 97/23/EC, category IV, safety equipment. Standard pressure switches Pressure switches for steam plant approved by Vd TUV Pressure switches with adjustable neutral zone Differential pressure switches

Technical data and code nos. When ordering, please state type The type designation and code number. for the letters below means: A: Unit suitable for the medium ammonia L: Unit with neutral zone RT 113 for manual setting; cover with windows RT 116 for tamper proof; cap and blank cover 4 Supplied with 06 / 010 mm weld nipple. / 2) With seal cap Pressure switches with adjustable neutral zone RT 262 A Differential pressure switch Preferred versions Regulation range pe 1) Supplied with 06 / 010 mm weld nipple Differential pressure switches Regulation range (Ap) 1) Supplied with 06 / 010 mm...

Technical data and ordering The designation letters mean: A: Units suitable for the medium ammonia. B: Safety units with external resetW: Units for control purposes. S: Safety units with internal reset Pressure switches for steam plant, PED approved acc. to EN 12953-9 and EN 12922-11 Pressure switches for low pressure steam plant (pressure monitoring)- not PED approved

Materials in contact with the medium

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 I.Alarm for rising pressure given at the set range value. 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). II. Alarm for falling pressure given at the set range value minus the differential. Scale setting Mechanical differential Units with...

Data sheet | Pressure switch, RT Function (continuation) Example I 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...

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...

Data sheet | Pressure switch, RT Application 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...

Range setting Inlet pressure Differential (mechanical differential) corresponds to the least neutral zone setting. 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. The neutral zone, 35 - 32 = 3 m wg, corresponding to 0.3 bar, must be set on the neutral zone...

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 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...