Double mechanical seals are offered in two arrangements:
Back to back
Two rotating seal rings are arranged facing away from each other. The lubricating film is generated by the barrier fluid. This arrangement is commonly found in the chemical industry. In case of leakage, the barrier liquid penetrates the product.
Face to face
The spring loaded rotary seal faces are arranged face to face and slide from the opposite direction to one or two stationary seal parts. This is a popular choice for the food industry, particularly for products which tend to stick. In case of leakage, the barrier liquid penetrates the product. If the product is considered “hot”, the barrier liquid acts as a cooling agent for the mechanical seal.