Differential Pressure Switch

MP 54, MP 55, MP 55A

Installation Guide

Danfoss

Refrigerants

The following refrigerants are approved for use with this switch:

R22
R134a
R404A
R407A
R407C
R407F
R422B
R422D
R448A
R449A
R450A
R452A
R507A
R513A
R717*)

*) Note: R717 is only approved for the MP 55A model.

For a complete list of approved refrigerants, please visit: http://products.danfoss.com/all-products/

Installation and Operation

This document provides installation guidance for the Danfoss Differential Pressure Switches MP 54, MP 55, and MP 55A.

Basic Principle

A schematic shows the differential pressure switch with two pressure ports labeled P1 and P2. A note indicates that the difference between P1 and P2 represents oil pressure.

MP 55 / MP 55A Operation

The MP 55 / MP 55A switch features a setting dial for adjustment. Pressure ports are labeled P1 and P2, and the differential pressure is indicated as P1-P2.

A timing mechanism is included for the 'Stop' function, initiating a 2-minute countdown before a reset occurs.

Testing Procedure

The 'TEST' section illustrates a pressure test setup. A pressure gauge is connected to the switch, which is in a 'MO OS' (Make or Open) configuration. A relay and timer are part of the test setup, with a 'NB!' (Note Bene) highlighting important information. The relay release times are specified as 45 sec., 60 sec., 90 sec., and 120 sec.

Connection and Settings

The switch has a maximum operating temperature limit of 100 °C (212 °F).

Connections can be made using solder, with Silfoss 15 (15% Ag) recommended.

For secure installation, a torque of M=20 Nm (15.5 ft-lbs) is specified, with a maximum insertion depth of 3 mm (1/8 in) for fittings.

An installation instruction shows a fitting being rotated 1.5 times (1.5x360°) for proper seating.

Pressure Ratings

The switch is rated for a System Pressure (PS) of 17 bar (Maximum Working Pressure MWP = 245 psig).

The maximum test pressure (Ptest max.) is specified as 22 bar (310 psig).

Wiring Diagram

A wiring diagram is provided to illustrate the correct electrical connections for the differential pressure switch.

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