Danfoss RT Series Pressure Switch Installation Guide
This guide provides installation instructions for Danfoss RT series pressure switches, including models RT 6W, RT 6B, RT 6S, RT 6AW, RT 6AB, RT 6AS, RT 30AW, RT 30AB, and RT 30AS. These switches are approved according to EN 12263 and CE marked according to PED (Pressure Equipment Directive).
Product Overview
The RT series pressure switches are tested and approved by TÜV (Technischer Überwachungs Verein). They are available in three main types: W (Druckwächter / pressure control), B (Druckbegrenzer / pressure limiter), and S (Sicherheitsdruckbegrenzer / safety pressure limiter).
Note: The designation ** applies only to RT 6AW, RT 6AB, RT 6AS, RT 30AW, RT 30AB, RT 30AS models.
Refrigerant Compatibility: The switches are compatible with refrigerants such as R22, R134a, R404A, R407A, R407C, R407F, R422B, R422D, R507A, and R717 (NH3). For a complete list of approved refrigerants, please refer to the Danfoss website and search for individual code numbers.
Functionality and Safety
In accordance with EN 12263 regulations, if the control bellows rupture, the refrigeration compressor will stop and cannot be restarted until the pressure control is replaced. If the outer bellows rupture, the cut-out pressure falls by approximately 4 bar below the setting, causing the control to break the circuit at normal condensing pressure, ensuring a fail-safe function.
General Operation: For all designs, when the system pressure exceeds the set point, the control automatically stops the system.
Specific Model Operation:
- RT 6W, RT 6AW, RT 30AW: Automatically cut in when the pressure falls below the setting with a fixed differential (Δp).
- RT 6B, RT 6AB, RT 30AB: Can be reset manually using an external reset button when the pressure falls below the setting with a fixed differential (Δp).
- RT 6S, RT 6AS, RT 30AS: Can be reset manually using an internal reset button when the pressure falls below the setting with a fixed differential (Δp).
Differential (Δp) values are fixed and detailed in the technical data table (Fig. 10).
Technical Data
The following table details the technical specifications for the RT series pressure switches.
| Type | Enclosure (1) | Reset | Pressure range [bar] | Differential (fixed) [bar] | Refrigerants | Max. working press. [bar] / [psig] | Max. test press. [bar] / [psig] | Ambient temp. [°C] |
|---|---|---|---|---|---|---|---|---|
| RT 6W | IP66 | automat. | 5 - 25 | 3.0 | fluorinated refrigerants | 28 / 406 | 38 / 551 | -40 - 70 (2) |
| RT 6B | IP54 | man. ext. | 10 - 28 | max. 1.0 | ||||
| RT 6S | IP66 | man. int. | ||||||
| RT 6AW | IP66 | automat. | 5 - 25 | 3.0 | fluorinated refrigerants | 28 / 406 | 38 / 551 | -40 - 70 (2) |
| RT 6AB | IP54 | man. ext. | 10 - 28 | max. 1.5 | R 717 (NH3) | |||
| RT 6AS | IP66 | man. int. | + fluorinated refrigerants | |||||
| RT 30AW | IP66 | automat. | 0.8 - 10 | max. 0.4 | + fluorinated refrigerants | 22 / 319 | 25 / 363 | |
| RT 30AB | IP54 | man. ext. | ||||||
| RT 30AS | IP66 | man. int. |
Notes:
- (1) Enclosure rating according to EN 60529 / IEC 529.
- (2) Ambient temperature range of -50 to -70 °C applies without PED certification.
Fitting and Mounting
A Pg13.5 cable gland set is supplied separately. To ensure the specified enclosure rating (IP66 for automatic reset units, IP54 for external reset units), this gland must be assembled as shown in Fig. 7. If the gland is not used with a cable, a metal blanking plug should be fitted.
Use the mounting holes (25 mm diameter, Ø5 mm). The pressure control can be mounted on the valve panel or directly on the compressor. If the unit is likely to be subjected to vibration, it should be mounted on a resilient base.
If pressure pulsations occur at the connection point, they should be effectively damped, for example, by connecting the RT unit to the system via capillary tubing (see Fig. 8).
Electrical Connection
Refer to Fig. 6 for electrical connection details. FASE indicates the phase connection. Cable diameter should be between 6-14 mm. Ensure the earth connection is made to terminal 38.
Contact Load: Contact load specifications are found on the switch cover or in Fig. 4. For example, a marking of 10 (4) A, 400 V ~ indicates a maximum load of 10 A ohmic and 4 A inductive at 400 V. The maximum starting current (L.R.) for motor cut-in may be up to seven times the inductive load. RT units comply with VDE* 0660, Test Class II requirements.
Setting
After removing the seal cap (7), set the cut-out pressure using the range spindle while observing the scale (9). Turning the range screw clockwise increases the cut-out pressure setting, while turning it anticlockwise decreases it.
Accessories
Refer to Figs. 8 and 9 for available accessories.
Diagram References
Fig. 1: General view of RT 6W, RT 6B, RT 6S pressure switches.
Fig. 2: Illustration of RT 30AW, RT 30AB, RT 30AS pressure switches.
Fig. 3: Internal components and connections.
Fig. 4: 1m cable assembly with 1/4 in x 1/2 in flare connection (Code no. 060-007166).
Fig. 5: 1m cable assembly with 3/8 in x M10 -0.75 connection (Code no. 060-008266).
Fig. 6: Electrical connection terminals: FASE (Phase), MOTOR, STOP, START.
Fig. 7: Assembly of the Pg13.5 cable gland for achieving IP66/IP54 enclosure ratings.
Figs. 8a, 8b, 9: Various accessories available for the RT pressure switches.
Fig. 10: Detailed technical data table.
We engineer a better future | Danfoss
