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Acting, not reacting: How leakages can be detected at an early stage and their causes can be eliminated
The thermal oil pump is the heart and also the driving force of a thermal oil system. It is therefore fundamental to reliable and safe system operation that the pump functions correctly.
Processes in many industrial manufacturing applications need to be heated – for example when producing plastic products, drying wood or heating presses or chemical reactors. For a temperature range of 200 to 400 °C thermal oils are usually employed in such systems. The systems require special heat transfer fluid pumps, whose reliable operation is fundamental to the functioning of entire production lines.
The failure and consequential downtimes of such a system can very quickly lead to massive costs, clearly exceeding the total value of the pump with a single mechanical seal.
Also: If, in the event of a failure of such a pump, hot heat transfer fluid (e.g. thermal oil) escapes, there is a significant risk of fire and/or environmental damage as such fluids are usually combustible and hazardous to the environment.
For this reason, natural wear or impending damage should be detected as early as possible to prevent incalculable risks and unscheduled downtimes.
Even the 4EYS mechanical seal, which has been specially developed for operation in thermal oil systems and for use with the SYT pump series, only has a limited service life. It is normal for a small, practically invisible amount of thermal oil to escape at all times. This minor leakage is actually desired as it ensures lubrication of the seal faces and is necessary for the mechanical seal to work properly. This function-related leakage is clearly below one gramme per hour for an intact mechanical seal.
However, if the leakage rate increases over time when the pump is in operation, this indicates progressive wear of the seal faces. Should such damage occur at a single mechanical seal, larger quantities of fluid may escape to the environment and may become a hazard to persons and the environment.
To monitor the amount of leakage: the KSB leakage sensor
It is common today for synthetic high-performance heat transfer fluids to be used in demanding processes. Given the potentially environmentally hazardous properties of these fluids we recommend an additional safety measure for heat transfer fluid pumps: the KSB Leakage Sensor for monitoring the leakage rate.
The KSB Leakage Sensor is an intelligent monitoring system for measuring and displaying on site the leakage of single mechanical seals . The system consists of a leakage rate measuring unit and an analysing and display unit which emits acoustic and light signals when the adjustable warning or alarm threshold is exceeded.
The benefits of continuous leakage monitoring are obvious:
- Increased operating reliability by preventing consequential damage and unscheduled downtimes
- Cost savings thanks to longer maintenance intervals and more predictable maintenance and repair cycles
- Fast and easy commissioning as well as integration into the customer’s process control system
For enhanced safety and even higher operating reliability of heat transfer fluid pumps: a double mechanical seal
In addition to a single mechanical seal, KSB offers a double mechanical seal, type 4EYT, for use with Etanorm SYT and operating mode to API Plan 52 (unpressurised tandem arrangement). For safety reasons, the double mechanical seal should generally be used for synthetic heat transfer fluids with a vapour pressure above 1 bar at operating temperature.
The 4EYT double mechanical seal is designed with a space filled with unpressurised compatible buffer fluid (e.g. a mineral oil) between the inboard mechanical seal and outboard mechanical seal, so it is impossible for any leakage of the fluid handled to escape to atmosphere. A supply system ensures that this space is always filled with buffer fluid to provide sufficient cooling (or lubrication) of the seal faces and to rule out any leakage of the fluid handled.
The use of a double mechanical seal also prevents any contact between the fluid handled and the rolling element bearing grease. Synthetic high-performance heat transfer fluids have a distinct tendency to creep. The double mechanical seal makes sure they cannot attack the rolling element bearing grease.
Horizontal volute casing pump in back pull-out design, single-stage, with ratings and dimensions to EN 733, radially split volute casing with integrally cast pump feet, replaceable casing wear rings, closed radial impeller with multiply curved vanes, single mechanical seal to EN 12756, double mechanical seal to EN 12756, drive-end bearings: rolling element bearings, pump-end bearings: plain bearings, with magnetless KSB SuPremE motor (exception: motor sizes 0.55 kW / 0.75 kW with 1500 rpm are designed with permanent magnets) of efficiency class IE4/IE5 and PumpDrive variable speed system; ATEX-compliant version available.
Volute casing pump for horizontal or vertical installation, back pull-out design, single-stage, with ratings to EN 733, radially split volute casing, replaceable casing wear rings, volute casing with integrally cast pump feet, closed radial impeller with multiply curved vanes, single mechanical seal to EN 12756, product-lubricated carbon plain bearing, grease-lubricated radial ball bearing in the motor housing, with magnetless KSB SuPremE motor (exception: motor sizes 0.55 kW / 0.75 kW with 1500 rpm are designed with permanent magnets) of efficiency class IE4/IE5 and PumpDrive variable speed system; ATEX-compliant version available.
Single-stage volute casing pump in in-line design, with magnetless KSB SuPremE motor (exception: motor sizes 0.55 kW / 0.75 kW with 1500 rpm are designed with permanent magnets) of efficiency class IE4/IE5 and PumpDrive variable speed system; pump shaft and motor shaft are rigidly connected. ATEX-compliant version available.