Conservator Rubber Capsule (Bladder)
The elastomer bag inside a sealed conservator that keeps transformer oil and air apart. Oil expands and contracts with load and ambient temperature; the capsule breathes with it, so the oil never contacts atmospheric oxygen or moisture. When the capsule hardens, cracks or loses elasticity, that separation is lost — and oil ageing accelerates across the whole unit.
* Values marked TBD are confirmed per order against factory datasheets and your conservator drawings.
What to Confirm Before Ordering
These six fields decide whether a replacement capsule fits and survives. If you have the conservator drawing, most of them are already on it.
| Field | Why it decides the outcome |
|---|---|
| Conservator internal diameter & length | Sets the capsule's inflated envelope. Too large and it folds and creases; too small and it cannot take the full oil swing. |
| Manhole / inspection opening size | The capsule has to go in through the opening. This is the single most common fit problem on site. |
| Oil type — mineral, synthetic ester or natural ester | Elastomer compatibility differs. A compound suitable for mineral oil can swell or harden in ester fluid, and vice versa. |
| Continuous & peak oil temperature | Drives compound selection and expected service life, especially in high-ambient Gulf installations. |
| Connection details — air vent, oil-side port, flange pattern | Determines how the capsule's inside vents to atmosphere, usually through the moisture absorber. |
| Original part number or transformer nameplate | When available, this is faster and safer than measuring. A nameplate photo is enough to start. |
Do not guess on any of the above. If a field is unknown, mark it as such and we will tell you what can be inferred and what must be measured.
Technical Data
| Item | Data |
|---|---|
| Model / size range | TBD* — dimensional chart PDF on request |
| Elastomer compound | TBD* — selected against your oil type and temperature |
| Operating temperature range | TBD* |
| Tensile strength / elongation / hardness | TBD* |
| Oil compatibility (mineral / synthetic ester / natural ester) | TBD* — state the fluid when enquiring |
| Manhole / flange opening | TBD* — per conservator drawing |
| Service life / recommended replacement interval | TBD* — follow the transformer manufacturer's maintenance schedule |
| Applicable standard | TBD* — confirmed per order |
| MOQ / lead time | TBD* — confirmed at quotation |
* To be confirmed per order against factory datasheets and your conservator drawings. We do not publish figures we have not verified.
Signs the Capsule Needs Replacing
Moisture rising in oil tests
Water content trending up in routine oil analysis with no other explanation points at a loss of the oil/air barrier.
Breather working far harder
If the capsule has failed, the conservator starts breathing directly and silica gel saturates much faster than its normal cycle.
Oil level behaving oddly
Level that no longer tracks load and temperature as it used to, or that drifts out of range, can indicate a collapsed or torn capsule.
Visible during overhaul
Hardening, surface cracking, permanent creases or a chalky surface once the conservator is opened — replace it while the unit is already open.
A capsule is cheap compared with the outage and the oil treatment it protects. Most workshops replace it as a matter of course whenever the conservator is opened. Pair it with a fresh gasket set and a moisture absorber service in the same visit.
Frequently Asked
Can you make a capsule without the original part number?
Yes, if you can supply the conservator's internal dimensions, the manhole or inspection opening size, and the oil type. A dimensioned sketch or a photo of the old capsule with a tape measure for scale is usually enough to start.
Is the capsule compatible with ester ( biodegradable ) fluids?
It depends entirely on the compound. Elastomers approved for mineral oil are not automatically suitable for synthetic or natural ester. Tell us the fluid at enquiry stage and we will confirm the compound — shown as TBD* until verified for your case.
Do you supply gaskets and the breather as well?
Yes. Capsules are commonly ordered together with conservator gasket sets, moisture absorbers and silica gel refills. Consolidating them into one shipment saves freight and customs handling. See spare parts for distribution substations for how a full list is bundled.
We only need one or two — is that acceptable?
Small quantities are accepted and are normally the reality for a single overhaul. Minimum quantity per line is TBD* and confirmed in the quotation; mixed orders with other accessory lines are welcome.
How should the capsule be stored before installation?
Store in its original packing, away from direct sunlight, ozone sources and heat, and do not fold or compress it. Storage guidance for the specific compound supplied is TBD* and included with the shipment documentation.
Back to the full transformer accessories range, or see where these parts are used in the field on the applications pages.
Send the conservator drawing — we will match the capsule
Nameplate photo, dimensions or the old part number. Matched offer within one business day.