In the temperature range up to approximately 200 °C, water is the preferred medium as it is non-polluting and has a high specific thermal capacity. In the temperature range from 200 °C to 400 °C, organic heat transfer liquids are preferable because the vapour pressure also rises considerably when the temperature increases. For handling these heat transfer media, volute casing pumps have been specially developed.

for Hot Water Volute casing pumps with uncooled mechanical seal according to EN 733 or EN 22858. Series ZHN, ZDN, ZEN, ZLI. Flow rate: up to 600 m³/h Head: up to 90 m

for Hot Oil Volute casing pumps with uncooled mechanical seal according to EN 733. Series ZTN, ZTK, ZTI. Flow rate: up to 1,000 m³/h Head: up to 95 m