The Low-Level Tank in Thermal Oil Systems: The Essential Safety Guardian

Industrial electric heating thermal oil systemshttps://8ruiyan.com/en/all-organic-heat-carrier-boilers/ rely on a critical protector: the Low-Level Tank (LOT). Often overlooked, it sits at the system’s lowest point and is vital for safety.

I. Core Functions: Safety First

1. Emergency Relief: Its primary role. Safety valves release hot oil during over-temperature or over-pressure events. The LOT safely contains this oil, preventing fires, explosions, or injuries.
2. System Drainage: Stores all oil drained during maintenance, repair, or oil changes.
3. Venting & Purging Buffer: Holds small amounts of oil released during system venting or purging.
4. Mandatory Requirement: The LOT is a mandatory safety-critical component. Relevant safety codes (e.g., China’s TSG specifications, ASME Boiler & Pressure Vessel Code) require its installation to ensure safe emergency discharge and system shutdown. It is the designated and reliable vessel for safe system venting.

II. Key Design Features

1. Lowest Point Location: Installed at the system’s absolute lowest spot (ground level or pit). Must be away from heat sources. Ensures gravity flow into the tank.
2. Atmospheric Operation: Works at ambient pressure. Vents to atmosphere via a breather valve (often with flame protection). Prevents pressure buildup.
3. Adequate Capacity: Must hold ALL system oil PLUS safety valve maximum discharge volume. Critical for safety.
4. Essential Features:
   • Insulation: Prevents surface burns.
   • Key Components: Level gauge, temperature gauge, pressure gauge, breather valve, manhole, drain valve.
   • Nitrogen Blanketing (Recommended): Prevents oil oxidation during storage.

III. Low-Level Tank vs. High-Level Expansion Tank: Know the Difference

Feature	Low-Level Tank (LOT)	High-Level Expansion Tank (HEP)
Main Job	Stores emergency & drain oil	Holds expanding oil, adds make-up oil, vents air
Role	Safety & emergency vessel	System operation buffer
Location	System’s LOWEST point	System’s HIGHEST point
Pressure	Atmospheric	Holds system pressure (often with N2 seal)
Normal State	Often empty	Always partially filled
In Oil Loop?	No	Indirectly yes
Mandatory?	YES, Safety Essential	YES, System Operation Essential

IV. Key Safety Practices

1. Comply with Standards: Design, fabrication, and installation must meet pressure vessel codes (e.g., ASME, TSG 21). The LOT is a regulatory requirement.
2. Correct Placement: Must be the true lowest point. Discharge pipes: short, straight, steep slope. Keep away from heat.
3. Verify Capacity: Re-check size after system modifications.
4. Regular Maintenance:
   • Ensure breather valve functions.
   • Check instrument accuracy (level, temp).
   • Maintain insulation.
   • Drain sludge regularly (if oil stored).
   • Maintain stable N2 pressure (if used).
5. Oil Quality Control: Rigorously test stored oil before reuse. Key tests: viscosity, acidity, flash point. Nitrogen preserves oil quality.
6. Train Staff: Ensure operators understand the LOT’s purpose and its critical necessity. They must know emergency procedures and maintenance.

Conclusion:

The Low-Level Tank is the silent safety hero. It doesn’t heat your process, but it protects your system. Its low position, simple design, and sufficient size are vital. Critically, it is a mandatory safety requirement per design codes – NOT an optional component. Understand its role. Install it correctly. Maintain it well. This is fundamental to thermal oil system safety.

Remember: For thermal oil safety, the Low-Level Tank is non-negotiable and mandatory.

For further consultation, please contact our technical team for expert advice.

Whatsapp:86-19106101570

wechat:86-19106101570

email:nieyili@cnryan.com

http://www.8ruiyan.com