- Erstellt: 15-11-21
- Letzte Anmeldung: 15-11-21
Mechanical Metal Bellow Seals
come in different configurations, and each variant has its advantages and disadvantages.
Among the most common variants are component mechanical seals and cartridge mechanical
CARTRIDGE VS. COMPONENT MECHANICAL SEAL
When selecting a mechanical seal type, pump users must consider the cost of
installation, long term running costs, pump characteristics, and the anticipated
operational conditions (heat, vibration, and pressure). Keep your technical staff in
mind as well, because having a skilled technician on-hand for regular maintenance vs.
having to outsource maintenance and repairs makes a significant difference.
These factors will determine whether a component seal is preferable to a cartridge
WHAT IS A CARTRIDGE SEAL?
A cartridge mechanical seal is a completely enclosed seal system with preassembled
components. Typically, this seal type is composed of a gland, sleeve, and other hardware
that make pre-assembly possible.
Refer to our blog post about different mechanical seal types for a more exhaustive
Advantages of Cartridge Type Mechanical Seals
The major benefits of choosing Cartridge Mechanical Seals for your pump seal system include:
Easy / Simple installation (No specialist necessary)
Higher functional security due to pre-assembled seal with fix axial
settings. Eliminate measuring errors.
Eliminated the possibility of axial misplacement and resulting seal
Prevention of dirt entry or damaging of the seal faces
Reduced installation costs through reduced installation time = Reduced down
times during maintenance
Potential to reduce the degree of pump disassembly for seal replacement
Cartridge units are easily repairable
Protection of customer shaft/shaft sleeve
No need for custom-made shafts to operate a balanced seal due to the
internal shaft sleeve of the seal cartridge.
WHAT IS A COMPONENT SEAL?
Component mechanical seals are composed of separate dynamic and stationary parts.
Unlike cartridge seals, Component Seals
are not preassembled and require skilled technicians to install them. Incorrect
installation of the seal faces, O-rings, and seal axial setting on the pump shaft will
result in reduced seal life or in some cases, immediate seal failure.
Advantages of O-ring Mounted Mechanical Seals
The benefits of selecting non-cartridge seals for your mechanical seal support
Reduced expenses on initial seal purchase
Reduced spares costs as the individual components can be stocked vs. the
Superior adaptability to very small pumps
Common Pumps Seals are simply a
method of containing fluid within a vessel (typically pumps, mixers, etc.) where a
rotating shaft passes through a stationary housing or occasionally, where the housing
rotates around the shaft.
When sealing a centrifugal pump, the challenge is to allow a rotating shaft to enter
the ‘wet’ area of the pump, without allowing large volumes of pressurized fluid to
To address this challenge there needs to be a seal between the shaft and the pump
housing that can contain the pressure of the process being pumped and withstand the
friction caused by the shaft rotating.
Before examining how mechanical seals function it is important to understand other
methods of forming this seal. One such method still widely used is Gland Packing.
Gland packing is a braided, rope-like material that is packed around the shaft -
physically stuffing the gap between the shaft and the pump housing.
Gland packing is still commonly used in many applications, however increasingly
users are adopting mechanical seals for the following reasons;
The friction of the shaft rotating wears away at the packing over time,
which leads to increased leakage until the packing is adjusted or re-packed.
The friction of the shaft also means that packing also needs to be flushed
with large volumes of water in order to keep it cool.
Packing needs to press against the shaft in order to reduce leakage – this
means that the pump needs more drive power to turn the shaft, wasting energy.
Because packing needs to contact the shaft it will eventually wear a groove
into it, which can be costly to repair or replace.
Pumps Mechanical Seals are designed to overcome these drawbacks.
A basic mechanical seal contains three sealing points.
The stationary part of the seal is fitted to the pump housing with a static seal –
this may be sealed with an o-ring or gasket clamped between the stationary part and the