Diaphragm/Air Bag: Volume Capacity 5-500 liters

Q: How often should a diaphragm be replaced?

Typically every 10-15 years, but inspect annually for cracks, hardening, or permeability issues.

Q: Can diaphragms be repaired?

No, damaged diaphragms must be replaced entirely to maintain seal integrity.

Q: What causes diaphragm failure?

Common causes include material degradation from UV exposure, chemical incompatibility, mechanical fatigue from frequent cycling, or improper installation.

Component Specifications

Definition

A diaphragm or air bag is a flexible, impermeable membrane installed within conservator tanks of oil-filled transformers. It creates a physical barrier between the insulating oil and atmospheric air, allowing for thermal expansion and contraction of the oil while preventing direct contact with oxygen and moisture. This component maintains oil quality by eliminating oxidation, reducing sludge formation, and minimizing dielectric breakdown risks.

Working Principle

The diaphragm operates on the principle of flexible separation. As transformer oil heats up during operation, it expands into the conservator tank, compressing the air bag. During cooling, the oil contracts, and the diaphragm expands to maintain positive pressure, preventing air ingress. This dynamic movement accommodates volume changes while keeping the oil isolated from atmospheric contaminants.

Materials

Typically made from nitrile rubber (NBR), ethylene propylene diene monomer (EPDM), or fluorocarbon elastomers (FKM) for chemical resistance. Reinforcement layers often include nylon or polyester fabric. Material selection depends on oil compatibility, temperature range (-40°C to +100°C), and UV resistance requirements.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Diameter	300-2000 mm
Thickness	2-5 mm
Permeability	<0.1 g/m²/day
Volume Capacity	5-500 liters
Temperature Range	-40°C to +100°C
Operating Pressure	0-0.5 bar

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 4633, DIN 53504, ASTM D2000

Parent Products

This component is used in the following industrial products

Conservator Tank (Expansion Tank)

A sealed tank connected to a power transformer's main tank that accommodates the thermal expansion and contraction of insulating oil.

View Product Details

Engineering Analysis

Risks & Mitigation

Material degradation leading to oil contamination
Rupture causing air ingress and transformer failure
Improper installation resulting in leaks
UV exposure reducing lifespan

FMEA Triads

Trigger: Material aging from prolonged UV exposure
Failure: Cracking and loss of impermeability
Mitigation: Use UV-resistant materials and install protective covers

Trigger: Chemical incompatibility with transformer oil additives
Failure: Swelling or hardening of diaphragm
Mitigation: Verify material compatibility through ASTM testing

Trigger: Overpressure from blocked breather vents
Failure: Rupture and sudden air ingress
Mitigation: Install pressure relief valves and regular vent maintenance

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±2% on dimensional specifications, leak-tight at 0.7 bar test pressure

Test Method

Pressure decay test per ISO 4633, material compatibility per ASTM D471

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Diaphragm/Air Bag

Manufacturer profiles associated with Diaphragm/Air Bag.

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Frequently Asked Questions

How often should a diaphragm be replaced?