The Monitor

Production Process Insights

Increase Sample Cooler Performance with Troubleshooting Tips

Posted by Joe Kreinus on 5/17/21 8:00 AM


Cooling samples as part of your steam and water sampling system is essential to maintaining safety and the sample's representativeness. But when your sample coolers aren't working as expected, knowing a few troubleshooting tips can address common issues to keep your coolers running smoothly.

A Single Helical Tube Sample Cooler is the most compact and highly efficient type of sample cooler. It includes a single continuous tube that's helically coiled and fitted in a shell. The sample to be cooled flows through the tube side of the cooler. The cooling fluid, usually water, flows through the shell side of the cooler.

Troubleshooting Your Sample Coolers

Before troubleshooting sample coolers, identify isolation valves and other safety components within your system to prevent equipment damage and personnel injury.

1. Inspect sample cooler installation.

  • Inspect cooling water headers and connections based on your manufacturer's IOM.
  • Ensure cooling water is within specifications for your specific design as supplied by the manufacturer, including maximum and minimum flow rates, supply pressure, and inlet temperatures.

2. Hone in the total sample flow.

  • Sample flow should typically be around 800 cc/min for steam samples and 1000-1200 cc/min for condensed liquid lines. Suppose a sample line is routinely tripping a TSV (Thermal Shutoff Valve). In that case, this could indicate a loss of cooling water flow rate, a reduction in cooler performance, or excessive sample flow rate.
Problem Solution
The sample line is routinely tripping a Thermal Shutoff Valve (TSV).
  • Identify and resolve the TSV trip.
  • Shut the VREL/PCV-1.
  • Reset the TSV.
  • Adjust the VREL/PCV-1 to return the sample flow rate to regular operation per your system specifications.


3. Visually inspect the outside of the coolers for signs of excess heat and/or corrosion.

  • Signs could include a browning label or excess build-up on the connections. Operators can also identify hot spots with the use of a thermal gun.
Problem Solution
The shell of the cooler is discolored, the label is melted.

There's a popping sound from the shell.

Bubbles are seen in the cooling water sight gauge outlet, if available.

The cooling water flow is too low, the sample cooler is fouled or has scale build-up inside, or the sample flow rate is beyond the cooler's capacity. Modify the flow rate and ensure the fouling has been cleaned to rectify.

There's excess heat in the sample.
  • Isolate the sample cooler from the sample and cooling water sides.
  • Drain and remove for inspection.
  • If the issue is caused by cleanliness, clean the sample cooler as outlined in the guidelines of your IOM.
  • Inspect for tube leaks.
  • Once cleaned and no tube leaks are observed, place back into service.
External tube scaling

Follow the cooler cleaning guidelines in your IOM.

Tube leak, indicated by loss of sample pressure and increased coolant exit temperature

This could signal an internal tube failure, resulting in higher coolant temperature across all samples on the same cooling header.

  • Isolate the cooler.
  • Drain and remove the cooler from service.
  • Pressure test the cooler per your manufacturer's guidelines.


4. Cooling water velocities shouldn't exceed recommended specifications for your system design.

Problem Solution
Cooling water velocity too high
  • Check cooling water header flow and pressure.
  • Utilize cooler outlet valves to throttle cooling water flow to provide backpressure.
  • If relief valves are present, make sure no cooling water is leaking to the relief header or drain.


5. Listen for any rattling within the cooler shell.

Problem Solution
Cooling water flow is too high indicated by rattling present in the cooler shell
  • Throttle the cooling water outlet valves.
  • Monitor the sample temperature and flow.
  • The sample temperature should not exceed 120° F (49° C) or the expected sample temperature on the cooler calculation sheet.


Sentry has extensive experience installing and maintaining sample coolers. Our experienced field technicians know what it takes to maintain water-based applications properly. Sentry can provide you with a tailored solution for your facility's sample applications.

Explore Sentry's sample cooling solutions. Learn more by downloading our Heat Exchangers 101 eBook.

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Topics: Power, Steam & Water

Written by Joe Kreinus

Picture of Joe Kreinus
As Director of Parts and Service, Joe Kreinus works with customers to actively improve company's sampling systems through specification development, review, installation, and maintenance. Joe is driven to find the best solution, parts, and service for the specific needs of each unique application and customer. He is committed to serving customers in all Sentry sampling markets. Joe also has a bachelor’s degree in chemistry from the University of Green Bay and enjoys coaching his three children in fast pitch softball and baseball.