Classic-line | A - Accessories - Spare-parts | diaphragms, springs | Hafner

Hafner Classic-line A Diaphragms and Springs

MB diaphragms and RU springs are internal replacement parts for Hafner Classic-line A pressure regulators. These components are specified for maintenance when pressure setpoint drift, slow regulator response, or confirmed mechanical wear of the diaphragm or adjustment spring is observed during operation.

MB Diaphragms

MB diaphragms are selected according to regulator size:

• MB-0: for unit A-0
• MB-1: for unit A-1
• MB-2: for unit A-2
• MB-3: for unit A-3

The diaphragm is critical for downstream pressure regulation. Wear, hardening, or leakage can result in unstable pressure, continuous venting, or deviation from the setpoint. Typical media include compressed air and inert gases within the specified temperature and pressure ranges of the Classic-line A series.

RU Springs

RU springs are selected based on regulator size and required outlet pressure range:

• RU-0-2 / -4 / -8 / -12: for A-0
• RU-1-2 / -4 / -8 / -12: for A-1
• RU-2-2 / -4 / -8 / -12: for A-2
• RU-3-2 / -4 / -8 / -12: for A-3

Spring codes (2, 4, 8, 12 bar) indicate the corresponding outlet pressure class. Selection must consider process requirements, media compatibility, and regulator certification (e.g., PED, ISO 8573-1).

Selection Criteria

Selection is based on:

• Regulator size (A-0 to A-3)
• Required outlet pressure
• Diaphragm condition
• Setpoint stability
• Compatibility with existing Classic-line units

Maintenance Guidelines

Before service, fully depressurize the line. After replacement, check for leakage, setpoint repeatability, gauge function, and regulator response to flow demand changes. Use only original parts to maintain compliance with operational and safety standards.