Bladders & bags we make
- Standard butyl bladders, NSF 61 and non-NSF
- EPDM and Viton bladders for artificial intelligence (AI) and data center liquid cooling loops
- High-temperature hydronic variants
- Sizes for ASME and non-ASME tanks up to roughly 4,000 gallons (15,000+ liters)
How we make them
- Material compounded and mixed in-house to formulations developed in our ISO/IEC 17025:2017 lab
- Proprietary formula for bladder cement developed and mixed in-house
- Collars and flanges molded in-house; bladders cut, built, and autoclave-cured on site
- Cutting operation largely automated for improved consistency and throughput
- Cement-bonded seams stronger than the base material itself
- 100% air tested before shipping
- Material certification available with shipments
- Made under ISO 9001, IATF 16949, and ISO 14001 certified quality and environmental systems
US-made bladders for AI data center cooling
Liquid-cooled artificial intelligence (AI) server racks run a closed coolant loop between a coolant distribution unit (CDU) and cold plates mounted on the chips. The expansion tank on that loop takes up the coolant's change in volume as rack heat rises and falls. In a bladder tank, the bladder is the only part of the tank the coolant touches, and every closed loop needs one.
The Open Compute Project (OCP) publishes guidelines for these loops, covering both treated-water and propylene glycol (PG25) coolants. Each guideline includes a list of acceptable wetted materials, and the water-based guideline names the reservoir bladder as a part that must comply. EPDM and Viton grades are on both lists. Butyl is on neither, which is why a data center loop takes an EPDM or Viton bladder rather than the standard butyl one.
Of the elastomers those guidelines name, we can supply bladders in all six: EPDM, Viton, nitrile, neoprene, Hypalon, and AFLAS. We are actively supplying both EPDM and Viton bags for AI cooling today. Importantly, we compound and mix material and then cut, build, cure, and air test finished bladders at our plant in Corry, Pennsylvania, where we have been making rubber products since 1961.
In September 2026, OCP released Revision 2.0 of its guideline for propylene glycol (PG25) coolant in liquid-cooled racks. EPDM is the first elastomer on its wetted-materials list, and the guideline recommends peroxide-cured EPDM: sulfur-cured EPDM can release sulfate into the coolant over time and lead to corrosion in the loop. The guideline puts typical loop temperatures at 17–66 °C (63–151 °F). It also calls for checking elastomers for changes in volume, weight, tensile strength and hardness after coolant exposure (ASTM D471, D412 and D2240). Our EPDM data center bladders are peroxide-cured, and our ISO/IEC 17025 lab can run those tests on bladder material soaked in your coolant.
Materials and testing
Corry Rubber bladders are made from custom materials developed in our ISO/IEC 17025:2017 lab. Where required, those materials are NSF 61 listed, odorless, and tasteless. Our NSF/ANSI 61 certified bladder and diaphragm compounds, M-660-1 and M-660-8, are approved for potable-water contact in ASME and non-ASME tanks: M-660-8 for tanks of four gallons and above, and M-660-1 for tanks of 20,000 gallons and above. View our active listings on the NSF certified-product database.
Each batch of bladder material is compounded and mixed in-house and tested for hardness, cure and numerous other physical properties. Collars are molded in-house. Calendered sheets of material are then cut to template, assembled as a built bladder, and autoclave-cured. In addition, expansion-tank bladders are bonded with our proprietary cement, formulated and mixed in-house alongside the bladder compound itself, joining the sheet material to the collars and producing joints stronger than the base material.
We have recently automated the bulk of our cutting operation for improved consistency and throughput as demand has grown. 100% of the bladders we manufacture are air tested before shipping, and where specified, shipments include material certification.
We have also developed bladder materials for high-temperature water applications (up to 140°C) and for storage of jet fuel, fuel oil, and kerosene.
Tank OEMs qualifying bladders for data center service and other applications can contact our bladder team for compound designations and certifications.