Taking Heat Transfer Fluid (HTF) samples is a necessary task to monitor the chemical hygiene of a Hot Oil/Thermal Oil/HTF system. For the purposes of this document, a system shall be referred to as a Thermal Oil system.
CHEM Group recommends sampling each Thermal Oil unit every six months or more frequently if the condition of the HTF requires. Monitoring the condition of the HTF may help operations:
- Optimized the performance of the HTF
- Detect operations issues with the HTF (or Thermal Oil system) that may not be externally evident
- Advise operations if the HTF is approaching the end of its useful life.
The following is a guideline on the recommended materials and steps for successfully pulling a Thermal Oil sample from a Thermal Oil system:
| Quantity | Material |
|---|---|
| 1 | 5-gallon (20-liter) metal pail |
| 1 | 9 feet (3-meter) copper coil |
| 1 | (pair per person) Hot gloves |
| 1 | CHEM Group Sample Kit |
| Quantity | Material |
|---|---|
| 1 | 5-gallon (20-liter) metal pail with water to cool simple coil |
| 1 | Pen for completing sample lables |
| Var | Wrenches (if needed) to assist in opening samples point/valves |
| Var | Rags |
- Sample should be taken from a vertical pipe that is part of the main heat transfer loop (i.e. NOT from the pipe leading to the expansion tank, or secondary heating loops).
- The system should be circulating when the sample is taken.
- The sample should be cooled to approximately 150°F (65°C). This is for operator safety and sample integrity. This can be achieved using a cooling coil (copper tubing) coiled inside a 5-gallon (20-liter) metal pail filled with water. The copper coil should be securely connected to the sample point so the HTF removed from the Thermal Oil unit passes through the copper coil, cooled as it passes through the sampling line (submerged in the water in the metal pail). About 1 quart (1 liter) of HTF should be collected into the dry metal pail to purge the line of any “impurities” and safely disposed according to the plant’s chemical disposal protocols.
NOTE: If step 3 is not followed, the sample may not be representative of the fluid in the system. Taking a sample without going through the above-described cooling coil may result in any light ends present in the sample eluting out of the sample at the elevated temperature, compromising the validity of that analysis. The analysis for Flash Point may indicate a higher temperature than actual. This may result in a safety hazard for plant operations.