BURKERT 348518 (Type 2031) is an externally controlled 2/2-way diaphragm valve with a pneumatic piston actuator and diaphragm seal. It uses neutral gases or air to control the flow of media. The proven and robust PA (Polyamide) actuator combined with a flow-optimised stainless steel valve body ensures reliable operation in hygienic or aggressive environments. This specific model features a DN 65 weld end connection, an EPDM high-temperature diaphragm, and operates with Control Function I (double-acting). The valve is self-draining when installed in the appropriate position.

Product Identification

The device can be identified by its type label, which contains vital operating parameters such as control function, diaphragm size, materials, and pressure limits.

Technical Data

Operating Conditions

• Medium: Neutral gases and liquids, ultrapure, sterile, aggressive or abrasive media.
• Control medium: Neutral gases, air.
• Permissible ambient temperature (PA actuator): -10 °C to +50 °C (for actuator size ≥175) / +60 °C (for actuator size ≤125).
• Permissible medium temperature (Stainless steel body): -10 °C to +140 °C (short-term up to 150 °C).
• Diaphragm medium temperature (EPDM): -10 °C to +143 °C (Steam sterilisation max. +150 °C for 60 min).

Pressure Limits

Do not exceed the maximum permissible pilot pressure or maximum permissible operating pressure. For this model, the nominal pressure is up to 7 bar, and the control pressure range is 4 to 6 bar.

Pressure-Temperature Diagram

The information in the pressure-temperature diagram is important for material selection. Observe the permissible operating pressure depending on the medium temperature.

Installation

Ensuring Self-Draining

The installer and the operator are responsible for ensuring self-draining. The inclination angle should correspond to the inclination angle of the pipeline. One of the relief bores in the diaphragm bonnet for monitoring leakages must be at the lowest position.

Welding the Valve Body

Damage to the diaphragm or the actuator

The diaphragm and actuator can be damaged when welding the valve body into the pipeline. Remove the actuator and diaphragm from the valve body before installation.

1. Remove the actuator from the valve body.
2. Weld the valve body into the pipeline.
3. After welding the surface of the valve body, smooth by sanding if necessary and clean carefully.
4. Install the actuator on the valve body.

Compressor Alignment

Risk of crushing

If the compressor is not positioned correctly and the actuator is actuated, this may result in injuries and damage to the device. Before actuating the actuator, ensure that the compressor is in the correct position.

Pneumatic Connection

For Control Function I (CF I): Connect the control medium to the upper and lower pilot air ports of the actuator.

• Pressure at upper pilot air port: valve closes.
• Pressure at lower pilot air port: valve opens.

Pilot Pressure Failure

For control function I: The valve stays in an undefined position in the event of a pilot pressure failure. To ensure a controlled restart, first pressurise the device with pilot pressure, then switch on the medium.

Maintenance and Repair

Inspection Intervals

• After the first steam sterilisation and when required: Tighten the body screws crosswise.
• After 10^5 switching cycles at the latest: Check the diaphragm for wear. Shortened inspection intervals are required for muddy and abrasive media.

Replacing the Diaphragm

Risk of injury from sudden discharge of pressure

Disassembling a pressurised device can cause medium to escape unexpectedly. Before disassembly, shut off the pressure and vent all lines.

1. Clamp the valve body in a holding device (if not installed).
2. Loosen the body screws crosswise and remove the actuator and diaphragm from the valve body.
3. Unbutton or unscrew the old diaphragm.
4. Attach the new diaphragm to the compressor according to the fastening type. The identification tab must be perpendicular to the flow direction.
5. Place the actuator together with the diaphragm on the valve body.
6. Pressurise the upper pilot air port with compressed air (valve closes).
7. With pressure, tighten the body screws in three stages (approx. 1/3, then 2/3 and then full tightening torque), in each case crosswise.