Sealing pressure (p_A) is the pressure actually applied at the mechanical seal. It is rarely synonymous with the terms suction pressure (p_S), discharge pressure (p_E) and operating pressure. For various centrifugal pumps, for example, the following applies:

• two-current centrifugal pumps: p_A » p_S
• one-current, single-stage centrifugal pump with balancing bores in the impeller: p_A » p_S
• one-current, single-stage centrifugal pumps with back vanes on the impeller:
  p_S < p_A < p_E

Formula for approximate values:
with n = 1500 rpm ;
with n = 3000 rpm ;

• multi-stage centrifugal pumps with balancing devices: p_S < p_A < p_E

Only the machine manufacturer is able to specify the actual sealing pressure.