A double mechanical seal consists of two seals arranged in a series. The inboard, or “primary seal” keeps the product contained in the pump housing. The outboard, or “secondary seal” prevents the liquid from leaking into the atmosphere. A double mechanical seal can be arranged either back-to-back or face-to-face:
Back to back
A face-to-face arrangement involves two seal rings connected on the spring side, with the sliding motion from the opposite direction to the stationary parts of the seal. The lubricating film is generated by the barrier fluid. This arrangement is commonly applied in the chemical industry.
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.
This kind of product is vital if the contents being processed are hazardous to the external environment, or aggressive media are used at high pressures or temperatures. Lepu Seal provides different materials for this double mechanical seal 208 based on the use conditions, including carbon, silicon, and tungsten carbide. Under the high temperature, rubber seal viton is highly recommended for the rubber part. Different shaft sizes ranging from 10mm to 45mm are also available.