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.
|The sample line is routinely tripping a Thermal Shutoff Valve (TSV).||
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.
|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.||
|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.
4. Cooling water velocities shouldn't exceed recommended specifications for your system design.
|Cooling water velocity too high||
5. Listen for any rattling within the cooler shell.
|Cooling water flow is too high indicated by rattling present in the cooler shell||
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.