At some point, thermal fluid systems will require a system cleanout due to ongoing excessive maintenance and/or operating problems, which cannot be rectified by simply replacing the fluid. In planning a system cleanout, users should consider the following issues:
- Number and location of system drain points
- Time frame available for cleaning or changeover
- Condition and compatibility of existing fluid
- Your manpower to perform the work
There are enough differences with each system and situation to make a single detailed procedure impractical or even incorrect for some cases. Several general options are presented below.
Flush with OIL UK FLUSHING FLUID
Procedure suggested for use when:
- System is not badly fouled
- Fluids are chemically compatible
- System is not difficult to completely drain
- Time is short
- If possible filter existing fluid using 40 microns or smaller to remove particulate from the system which might not drain out with the fluid during the draining process.
- Run system at 200 °C (or just below the flash point) to mix well and suspend all the loose particulate in the thermal fluid.
- Stop the heater and allow the temperature to drop with the circulating pump going.
- Allow the system to cool to an acceptable temperature, stop the system pump and drain the thermal fluid quickly from all low points. If insufficient drains exist to remove 85-90% of fluid, install some hot tap drains at low points prior to trying to drain the system.
NOTE: Personnel should exercise appropriate caution when working around hot fluid - remember that Safety Comes First. The benefit of hot draining is that it prevents sludge and tars from re-depositing in the system.
- Recharge the system 100% with OIL UK FLUSHING FLUID from all the low point drains to prevent air pockets from developing. If there are system high point vents, open them and fill the system until oil comes out & close them. Start the circulation in the system without heat to help remove any air pockets - you will hear them working their way into the expansion tank. When all air pockets are removed, apply heat.
If using THERMALTRANS FLUSHING FLUID circulate for a maximum of 150 hours above 94°C or at operating temperature. 205 °C is ideal and can be ran up to 316 °C. Reduce heater outlet temperature to 108 °C at end of time prior to draining out fluid to ensure smooth removal of all fluid and particulates gathered with the Flushing Fluid.
- Turn off the heater and allow the temperature to drop while keeping the circulating pump on. When at an acceptable temperature, stop the system pump and drain quickly.
- Recharge the system with new Heat Transfer Fluid and restart.
Flush with the addition of OIL UK FLUSHING ADDITIVE CONCENTRATE
Procedure suggested for use when:
- Fluids are not compatible and different type of Heat Transfer Fluid is used
- System has some particulate and loosely adhering carbonaceous deposits
- System is badly sludged up or flow is restricted in some areas
- If possible filter existing fluid using 40 microns or smaller to remove particulate from the system which might not drain out with the fluid during the draining process.
- Run system at 200°C (or just below the flash point) to mix well and suspend all the loose particulate in the thermal fluid.
- Stop the heater and allow the temperature to drop with the circulating pump going.
- Allow the system to cool to an acceptable temperature, stop the system pump and drain the thermal fluid quickly from all low points. If insufficient drains exist to remove 85-90% of fluid, install some hot tap drains at low points prior to trying to drain the system.
NOTE: Personnel should exercise appropriate caution when working around hot fluid - remember that Safety Comes First. The benefit of hot draining is that it prevents sludge and tars from re-depositing in the system.
- Add OIL UK Flushing Additive Concentrate at anywhere between 5% to 10% (depending on how badly degraded the fluid is in the system) to the existing fluid by using a secondary pump on the suction side of the system pump. Do not add in through the expansion tank. Circulate for a maximum of 48 hours at operating temperature. Reduce heater outlet temperature to 108 °C at end of time prior to draining out. This is to ensure smooth removal of all fluid and particulates. If the system fluid has been severely degraded, we recommend recharging the system 100% with OIL UK Flushing Fluid and circulate for a maximum of 150 hours above at operating temperature. 205 °C is ideal and can be ran up to 316 °C. Reduce heater outlet temperature to 108 °C at end of time prior to draining out Thermaltrans Flushing Fluid to ensure smooth removal of all fluid and particulates gathered with the Flushing Fluid.
NOTE: When recharging your system, fill from all the low point drains to prevent air pockets from developing. If there are system high point vents, open them and fill the system until oil comes out & close them. Start the circulation in the system without heat to help remove any air pockets - you will hear them working their way into the expansion tank. When all air pockets are removed, apply heat.
- Turn off the heater and allow the temperature to drop while keeping the circulating pump on. When at an acceptable temperature, stop the system pump and drain quickly.
- Recharge the system with new Heat Transfer Fluid and restart.
Time - A common mistake is to try to squeeze a clean out into a weekend with a Monday morning production start-up. This is practical only for small, non-complicated systems. Considerable time at temperature is required for cleaning. Good flushing is not done quickly.
Disposal - Uncontaminated Oil UK heat transfer fluids can be taken by a waste oil hauler (oil recycler) and disposed of like used motor oil. A contaminated fluid must be handled according to what contaminated the oil. Check local regulations. Some cleaning service companies also arrange for fluid disposal as part of their service.
