Remote Seals vs Impulse Lines
Side by side comparison: how they work, where each fits, and which to choose.
Quick answer: Remote seals avoid plugging, freezing and leaks but add temperature error and slower response; impulse lines are cheap and accurate but need care.
Remote Seals vs Impulse Lines: Comparison Table
| Aspect | Remote Seals | Impulse Lines |
|---|---|---|
| Plugging and freezing | Avoided | Possible; tracing and purging needed |
| Temperature error | Fill expansion and capillary head | Small |
| Response | Slower with long capillaries | Fast |
| Maintenance | Cannot be refilled in the field | Drain, vent, refill |
| Cost | Higher | Lower |
Choose Remote Seals when
- Viscous, crystallising, corrosive or hot fluids
- Sanitary and toxic service
Choose Impulse Lines when
- Clean fluids and short taps
- Fast responding flow loops
Key Differences Explained
Impulse line problems such as gas pockets in liquid lines or liquid in gas lines are a leading cause of DP errors. Seals remove them but bring their own errors from fill expansion and capillary head.
Balanced capillaries of equal length on both sides, protected from sun, reduce seal errors.
Related Glossary Terms
Free Calculators
Frequently Asked Questions
What is the difference between Remote Seals and Impulse Lines?
Remote seals avoid plugging, freezing and leaks but add temperature error and slower response; impulse lines are cheap and accurate but need care.
Why do sealed DP transmitters drift in sun?
Uneven heating of capillaries expands the fill differently on each side.
Can I shorten a capillary?
No; capillaries are sealed and filled at the factory.
What is a direct mount seal?
A seal bolted directly to the transmitter without capillary, reducing error.
Learn more on the blog
Differential pressure transmitter working principle
A practical guide on instrumentationblog.in that goes deeper into this topic with field examples.
Read Full ArticleMore Comparisons
All comparisons · Instrumentation glossary