Complete Containment
No leaks or potential for release of product to atmosphere are intrinsic benefits offered by magnetic drive sealless pumps. The high integrity design uses a single static gasket to provide a leak free solution, rather than relying on complex single or multiple mechanical seals and their associated support systems, between the drive and the impeller.
Secondary Containment used to be the sole province of canned motor pumps (CMPs). However, HMD Kontro offer this optional feature for sealless magnetic drive pumps. This not only gives a real alternative to the integrity claimed by canned motor pump vendors, but also offers the additional benefits of site serviceability that is unique to the magnetic drive pump design.
This design utilised by HMD Kontro fully meets the requirements stated in API685 and, coupled with pressure or level switches, provides a high level of integrity and monitoring. No separate ancillary supplies are required, other than power for the instruments.
It is important to explain the difference between the primary and secondary pressure boundaries of the magnetic drive pump. The primary pressure boundary comprises the pump casing, generally a thick walled, cast component sealing the process to atmosphere, and a thin walled containment shell between the two parts of the magnetic coupling.
Secondary Containment
The containment shell is located inside a coupling housing which may, as a design option, be sealed to form a secondary pressure boundary. A dry running mechanical seal, between the rotating shaft and the static coupling housing, completes the sealing of the secondary pressure boundary. In the unlikely event of a primary pressure boundary failure involving the containment shell, process liquid is confined within the secondary pressure boundary. The dry running mechanical seal allows the coupling housing to fill and the pressure to increase, providing secondary containment to the magnetic drive pump and preventing any leak or escape of the process liquid.
With the secondary containment design option, pump instrumentation is used to alarm and shut down pump operation should a primary pressure breach occur. This instrumentation can comprise a pressure sensor and/or a liquid level probe fitted to the coupling housing. For low vapour pressure liquids a liquid sensing probe is suggested, for high vapour pressure liquids a pressure sensor. These should be set to stop the pump immediately if a leak is detected.
Secondary Control
HMD Kontro also offer Secondary Control that meets the requirements of API685. This is a variation on the above containment concept, which controls and safely directs any leakage resulting from an extraordinary breach of the containment shell. This feature consists of a lower pressure magnetic seal, a coupling housing drain connection, pressure switch, and non-fragmenting burst disc. In the unlikely event of an extraordinary breach of the containment shroud, this system would direct and safely control any leakage into the low-pressure drain system.
Once pressure increases in the coupling housing, the bursting disc safely opens and allows safe drainage of the liquid. During this process the pressure switch, whose signal detects the pressure that is built up in the coupling housing, can be used to safely stop the pump.
Pump monitoring and control systems such as Thermocouple / RTD protection and Power Condition Monitoring, provide a signal that can be used to both continuously monitor or stop and isolate a pump as required further enhancing the integrity of either secondary system.
With the addition of these secondary containment & control features, the applications for sealless pumps are further enhanced and expanded, creating an even higher, integrity, site serviceable pumping solution. For further information, please contact us.
Sealless pumps are self-contained as standard. The pumped product or liquid is completely enclosed within the body of the magnetic drive pump, exactly where it should be, providing significant safety benefits and greater security against environmental risk, plus much improved confidence in your corporate responsibility.
The containment shell is located inside a coupling housing, which may as a design option be sealed to form a secondary pressure boundary. In the unlikely event of a primary pressure boundary failure involving the containment shell, process liquid is confined within the secondary pressure boundary.
Benefits:
- Immediate shut down of the pump if a leak is detected
- Conforms to API 685 standards
- High degree of monitoring
- Reliable, efficient and environmentally friendly
In the unlikely event of an extraordinary breach of the containment shroud, this system will direct and safely control any leakage into a low-pressure drain/flare system.
Secondary Control Devices to Restrict Leakages into the Immediate Locality
Once pressure increases in the coupling housing, the bursting disc safely opens and allows safe drainage of the liquid. During this process the pressure switch, which has a signal to detect the pressure that is building up in the coupling housing, can be used to safely stop the pump.
Features:
- Variable Frequency Drive (VFD)
- Control panel with start/stop buttons
- Alarm and shut down features
- Pressure sensor and/or liquid level probe
If you would like to know more about the HMD Kontro Secondary Containment options for your sealless magnetic drive pump, please call +44 (0) 1323 452000 or email us.
