Mechanical seals are used in plumbing systems to prevent fluid leakage by maintaining pressure. There are different types of mechanical seals suitable for various applications. The main types discussed are pusher seals, non-pusher seals, unbalanced seals, balanced seals, and cartridge seals. Pusher seals are inexpensive and widely available but rely on a secondary seal. Non-pusher seals do not require a moving secondary seal. Cartridge seals are pre-installed but are more expensive and may not always fit existing settings. Buyers should understand the application and liquid to select the appropriate seal type and quality.

1. Types of Mechanical Seals
Mechanical seals are the devices which help to join
parts together in a mechanism preventing leakage
of fluid. Basically they are used in plumbing system
and they stop water leakage by maintaining
pressure they poses. Obviously there are lots of
plumbing mechanisms requiring different types of
joints. Various types of seals are available in the
market. A buyer must know their configuration to
understand which design will meet his
requirements.
Types of mechanical seals and their characteristics
are given below for your ease to choose the right
one for you:
1. Conventional seal
2. Pusher Seal
3. Non-pusher Seal
4. Unbalanced Seal
5. Balanced Seal
6. Cartridge
Pusher seal basically is installed with moving secondary seal. As its name shows, it moves on the sleeve
or shaft maintaining the contact over seal’s face. It assists to lodge wear properly and to help the
incorporated shaft alignment. The major advantage of this sort of seal is that they are easily available in
market. They are quite cheap and widely ranged. The disadvantage of pusher seal is that it depends
upon secondary seal. The hang-up of sleeve or shaft can always be hazardous to this seal. So if you are
expecting that the secondary seal will create any issues specially bearing weight, don’t choose pusher
seal.
Unlike pusher seal, non pusher seal doesn’t require secondary seal which is moving along on shaft. In its
installation, secondary seal is still all the time, even if the machine is working. The secondary sealing
device is not compulsory to accommodate rotary movement. Its plus point is that it can bear very low
and high temperature and it is not leveled to another seal (secondary). Such seals are installed to water
applications commonly.
Cartridge seal is having the mechanical seal which is pre-mounted on a shaft (gland included). They
directly fit on shaft sleeve or sleeve. Cartridge seal is available in single or double configuration. Pump
users mostly recommend and use cartridge seal for the best and long life performance. The primary
advantage of this seal is that the user can get rid of measuring the setting to install this. Maintenance
cost really reduces if you are using cartridge seal plus it lessens the chances of seal setting faults. Main
negative characteristic of this seal is that it is very expensive so mostly user cannot afford to buy this. It
sometimes doesn’t fit in the setting preinstalled.

2. The buyers can only choose the right seal if they know the proper setting and the sort of liquid it is going
to handle. Seals are available in a wide cost range, metal and quality. A wise buyer will not prefer price
over quality for sure.