Emerson PS1/PS2 Pressure Controls Operating Instructions

General Information

These operating instructions are for Emerson's PS1 and PS2 series pressure controls, designed for use in refrigeration systems and heat pumps. The devices have a potential ignition source and are not qualified according to ATEX standards, thus requiring installation in non-explosive locations only.

Safety Instructions

• Read all operating instructions thoroughly. Failure to comply may result in device failure, system damage, or personal injury.
• This product is intended for use by qualified personnel with appropriate knowledge and skills, such as those trained according to EN 13313 or with specific training for flammable refrigerants.
• Flammable refrigerants require special handling and care due to their flammability. Sufficient ventilation is essential during system service.
• Contact with rapidly expanding gases can cause frostbite and eye damage. Proper protective equipment (gloves, eye protection, etc.) must be used.
• Ensure the system is correctly labeled with the applied refrigerant type and a warning for explosion risk.
• In severely contaminated systems, avoid breathing acid vapors and skin contact with contaminated refrigerant/lubricants to prevent injury.
• Before opening any system, ensure the pressure is brought to and remains at atmospheric pressure.
• Do not release any refrigerant into the atmosphere.
• Do not exceed the specified maximum ratings for pressure, temperature, voltage, and current.
• Ensure the system piping is grounded.
• Before installation or service, disconnect all voltages from the system and device.
• Observe and avoid mechanical damage to the housing to maintain the protection class.
• Do not use any other fluid media without prior approval from EMERSON. Use of unlisted fluids could change the product's hazard category and conformity assessment requirements.
• Ensure that design, installation, and operation comply with European and national standards/regulations.
• For flammable refrigerants, only use valves and accessories approved for them.

Function

The PS1/PS2 pressure switches are equipped with SPDT snap-action contacts. They switch from terminal 1-2 to 1-4 on rising pressure and from 1-4 to 1-2 on falling pressure.

Fig. 1a: Automatic Reset Function:

[Diagram showing automatic reset function with terminals 1, 2, 4, 11, 12, 14, 21, 22 and PS1/PS2 labels]

Fig. 1b: Manual Reset Function (Low Pressure):

Fig. 1c: Manual Reset Function (High Pressure):

For PS1/PS2 with manual reset (high or low pressure reset): Upon reaching the preset switching point, contact 1-4 switches to 1-2 (low pressure switch) or from 1-2 to 1-4 (high pressure switch) and locks in this position. After the pressure rises or drops by a fixed differential, the switch can be reset by pushing the reset button.

[Diagrams for Fig. 1b and Fig. 1c showing manual reset functions with terminals and PS1/PS2 labels]

Mounting Location

Any direction is acceptable, except upside down.

Installation

Fig. 2: Installation

• PS1/PS2 controls can be installed using a mounting plate or directly mounted against a flat surface.
• Use universal thread M4 or UNC8-32 mounting holes for installation via a mounting plate.
• Use the standard mounting holes on the backside for wall mounting.
• Use the mounting screws supplied with the control.
• Mounting screws must not penetrate the control backside by more than 8 mm to ensure proper operation.
• Do not use PS1/PS2 in pulsating operating conditions.
• To achieve protection class IP44, observe the following: The cover must be closed and the cover screw fastened. The control must be mounted against a flat surface so that all openings on the housing backside are fully covered.

Pressure Connection

Fig. 3: Pressure Connection

• The pressure connection depends on the exact model and pressure connector.
• When connecting PS1/PS2 to the hot gas line of a refrigeration system, use a pipe, capillary, or flexible tube of at least 80 mm to allow sufficient temperature drop between the refrigeration line and the pressure switch bellows.
• Threaded Connection: For connectors A & C, do not apply torsional load to the pressure connector; use a second spanner to counter-balance torque when tightening. For K-type connectors, use the copper gasket supplied.
• Brazing Connection: Perform brazing joints as per EN 14324. Clean tubing and brazing joints before and after brazing. Minimize vibrations in the piping lines. Do not exceed the maximum surface temperature of 70 °C.

Pressure Test

After installation, a pressure test must be carried out according to EN 378 for systems complying with the European Pressure Equipment Directive 2014/68/EU, or to the maximum working pressure of the system for other applications.

Tightness Test

Conduct a tightness test according to EN 378-2 with appropriate equipment and method to identify leakages. The allowable leakage rate must be per the system manufacturer's specification.

WARNING: Failure to pressure test or tightness test as described could result in refrigerant loss, property damage, and/or personal injury. Tests must be conducted by skilled personnel aware of pressure-related dangers.

Electrical Connection

Fig. 4: Electrical Connection

• Entire electrical connections must comply with local regulations.
• Wire size must match the electrical load connected to the switch contacts.
• Ensure cables are mounted without tension; leave cables slightly loose.
• Ensure cables are not mounted near sharp edges.
• Do not bend or mechanically stress the cable outlet; maintain a clearance of 20 mm to neighboring parts.
• Feed cables through the rubber grommet at the switch bottom. Optionally, replace the grommet with a standard PG 13.5 cable gland.
• Connect wires to terminals considering switch functions as shown in Figs. 1a to 1c.
• Fasten terminal screws with a torque of 1.2 Nm maximum.
• For electronic applications with low electrical loads (voltage 24 V and current <50 mA), gold-plated contacts are recommended.

[Diagram showing electrical connections with labels for terminals, grommet, etc.]

Setpoint Adjustment

Fig. 5: Setpoint Adjustment

• PS1/PS2 pressure switches feature individually adjustable range and differential depending on the model. Manual reset switches have a fixed differential.
• Use a flat screwdriver or a 1/4" refrigeration (square) wrench to adjust setpoints.
• Adjust the upper setpoint using the range spindle (1).
• Adjust the lower setpoint by turning the differential spindle (8). The relationship is: Upper setpoint - Differential = Lower setpoint.
• A separate gauge must be used for exact adjustment. The integrated display scale is only for approximate settings.
• When changing the upper setpoint, re-check the lower setpoint.
• Refer to the Emerson catalogue or Technical Information for standard factory settings.

[Diagram showing setpoint adjustment spindles and scales]

Manual Reset / Universal Reset

Fig. 6a-c: Manual/Universal Reset

• Manual Reset (External): Press the reset button (1) as shown in Fig. 6a.
• Manual Reset (Internal): Remove the housing cover and press the reset button (2) as shown in Fig. 6b. The reset is 'trip-free', meaning it's only possible if the pressure has reached its reset threshold.
• Universal Reset: Remove the cover and change the universal toggle to the desired position (manual (3) or auto reset (4)) as shown in Fig. 6c.

Check-out Lever

Fig. 4 & Fig. 7: Check-out Lever

• Use the check-out lever to manually override the electrical contact position for testing the system.
• For low-pressure switches, the check-out lever can be used to manually override the electrical contact position for evacuating the refrigeration system.

Service / Maintenance

• Disconnect electrical power before performing any service.
• When performing repair work or replacing the control, always use a new gasket (K-Types).
• According to EN 378-4, tightness tests must be carried out on the relevant part of the refrigerating system during each periodic maintenance. This applies also after any repair where appropriate.

Technical Data Summary

The document also includes detailed technical data tables covering medium compatibility, electrical ratings, temperature ranges, pressure limits, vibration resistance, standards, and dimensions for both PS1 and PS2 models. These tables specify different fluid groups (A1, A2L) and their compatible refrigerants, as well as electrical contact ratings for various load types (AC1, AC15, DC13).

Type Code Description: Detailed explanations are provided for the PS1 and PS2 type codes, outlining various functions (e.g., automatic reset, manual reset, safety cutout, limiter) and pressure connections (e.g., threaded, capillary, ODF solder). Pressure ranges are also specified in bar.