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Thank you for subscribing to Paratherm TipSheet, a short,
monthly technical email series for users of thermal fluids and systems.
Paratherm continues the series with this sixth installment, "Proper
System Start-up". Among the topics addressed in future TipSheets
will be types of heating for process applications, thermal
fluid selection and analysis, system selection, design, installation,
maintenance and troubleshooting, and cost/benefit analysis.
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In last month's TipSheet we discussed the importance of proper
shutdown procedures for thermal fluid systems. However, significant
damage to fluids -- and equipment – can also occur if the system
is started improperly.
All thermal fluids become less viscous as temperature
increases. As the fluid gets thinner, its efficiency (heat
transfer coefficient) increases dramatically.
At temperatures below 100°F, most high-temperature thermal
fluids have viscosities greater than 10 centipoise, and won't flow efficiently.
At start-up, this cold fluid is not able to flow as well and absorb as
much heat from the heater tubing compared to when it's hot. If the temperature
rises too quickly, the fluid film at the heated surface may begin to
crack, damaging the fluid on a molecular level. If the system has a repeated
on-duty off-duty cycle, this damage will re-occur with each start-up.
Remedy? When cold, always start the system raising the heater
setpoint in 10 to 20°F increments until the fluid reaches turbulent
flow.
For more technical data on Proper Start-up Procedure contact our
engineering staff at 1-800-222-3611, or visit this link...
Process
Heating Magazine: Avoid Thermal Degradation
...to a complete article in Process Heating Magazine, titled; Avoid
Thermal Degradation Problems; Improper startup as well as improper shutdown
of thermal fluid systems can lead to premature fluid degradation.
If you'd like to receive these TipSheets™ on a monthly basis via email,
please enter your name and email below.
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