A seal pot, also known as a condensate pot, is a vessel used in differential pressure (DP) measurement systems to maintain a stable fluid column and prevent process fluids from entering the impulse lines or transmitters. It is commonly used in steam, corrosive, or high-temperature applications.
Purpose of a Seal Pot:
- Protects the DP Transmitter – Prevents hot steam or aggressive chemicals from damaging sensitive instruments.
- Ensures Stable Pressure Readings – Maintains a liquid column to avoid pressure fluctuations.
- Prevents Contamination – Stops process fluids from entering impulse lines and causing clogging or corrosion.
- Used in Wet Leg Systems – Helps maintain a constant liquid level for accurate level measurement in closed tanks.
Working Principle:
- The seal pot is installed in the impulse line between the process and the DP transmitter.
- A seal fluid (such as water, glycol, or special oil) is filled inside the pot to create a buffer.
- For steam applications, the pot allows condensation to collect, ensuring that only liquid, not steam, reaches the transmitter.
- For corrosive fluids, the pot prevents direct contact between the process fluid and the impulse tubing.
Types of Seal Pots (Condensate Pots):
1. Steam Service Seal Pot
- Used to condense steam before it reaches the DP transmitter.
✅ Application: Boiler drum level measurement, steam flow measurement.
2. Corrosive Process Seal Pot
- Used with a non-corrosive seal fluid to prevent aggressive chemicals from entering impulse lines.
✅ Application: Chemical and petrochemical industries.
3. Wet Leg System Seal Pot
- Maintains a constant fluid level in closed tank DP level measurements.
✅ Application: Pressurized storage tanks in oil & gas, refineries.
Installation Considerations:
✔ Mounted at the correct height – Ensures proper liquid column balance.
✔ Material selection – Stainless steel (SS316) or special alloys (Hastelloy) for corrosive applications.
✔ Seal fluid choice – Compatible with the process to avoid contamination.
✔ Proper venting & draining – Avoids air pockets or blockages.
Advantages of Using a Seal Pot:
✔ Protects transmitters from heat and corrosion.
✔ Ensures stable and accurate DP measurements.
✔ Extends the life of impulse lines and instruments.
✔ Prevents clogging and reduces maintenance.