Selecting a mechanical seal
How to move from a leaking pump to the right mechanical seal — covering balance, arrangement, face materials and flush plan, the four decisions that set reliability.
Map the duty first
Capture shaft size and speed, seal-chamber pressure and temperature, the fluid and its vapour margin, and whether it carries solids. These numbers decide everything downstream. A fluid running close to its boiling point at the seal faces, or one carrying abrasives, changes the selection far more than the headline service description does.
Choose balanced vs unbalanced
Unbalanced seals are simpler and suit low-pressure, benign duty. As seal-chamber pressure rises, the closing force on the faces generates too much heat — so above a few bar, or on volatile and hot fluids, specify a balanced design that reduces net face load and runs cooler. Cartridge construction then removes setting error on installation.
Match the face and elastomer materials
Silicon carbide against carbon is a strong general pairing; go to silicon carbide against silicon carbide for abrasive or marginal-lubrication duty. Select the secondary seal (O-ring) elastomer for the media: FKM for hydrocarbons, EPDM for hot water and chemicals, and PTFE-encapsulated for aggressive or mixed chemistry.
Specify the support plan
Few seals fail because of the seal alone — most fail because the environment at the faces was wrong. Add the appropriate flush, quench or barrier-fluid plan to control temperature, clear solids and maintain a stable film. For hazardous or unstable fluids, consider a dual seal with a barrier or buffer fluid to guarantee containment.
Take it from reference to recommendation.
Send your service conditions — media, temperature, pressure and motion — and our engineers will specify the exact seal, material and construction for the duty.