Which Rubber Expansion Joints to Choose for Water-Glycol Solution at 100°C with 37 Vol.%?

As indicated in the title, a customer inquired: Nominal Diameter: DN65, Pressure: 1.6MPa, Temperature: 88-100°C, Medium: Water containing 37 Vol.% of Ethylene Glycol. How to choose to ensure better service life?

Answer: For water containing ethylene glycol, it is recommended to use oil-resistant rubber expansion joints, specifically those made of nitrile rubber, ensuring the use of high-quality nitrile rubber. Shanghai Songjiang Group’s oil-resistant rubber expansion joints are all made of N41 nitrile rubber, with a content of about 50%. Moreover, both the inner rubber layer, reinforcement layer, and outer rubber layer are all made of nitrile rubber.

Further Inquiry: Can a commercially available oil-resistant rubber expansion joint be used?

Response: It cannot be guaranteed, as generally, commercially available oil-resistant rubber expansion joints have an inner rubber layer of nitrile rubber with a content of less than 10%, and both the reinforcement layer and outer rubber layer are made of ordinary rubber, which is definitely not suitable for use.

Further Inquiry: Some manufacturers suggest using polytetrafluoroethylene. Is this acceptable?

Response: No, because the temperature range is 88-100°C. While using PTFE lining would be suitable for temperatures below 30°C, at higher temperatures, the PTFE lining would deform, leading to pipe blockage or even rupture.