Heated Sample Probe Assemblies

Why Heat a Probe?

A standard sample probe sits at ambient temperature on its air-side end and at process temperature on its wetted end. Anywhere along the temperature gradient, the local probe wall can dip below the dew point of the process fluid, condensing heavy components out of the vapor phase. The result is composition bias, fouling, and accelerated cycle-life consumption.

A heated probe maintains the wetted surface above the relevant dew point — typically the hydrocarbon dew point in natural gas custody transfer, or the wax appearance temperature in crude oil sampling.

Heating Methods

Electrical Trace Heating

A self-regulating heat trace cable is wound around the wetted shank and the gland and energized to maintain a setpoint temperature. The PID controller is typically housed in a NEMA 4X enclosure with an explosion-proof rating where required. Power demand is calculated from probe length, ambient temperature, and target setpoint.

Steam Trace Heating

A small steam tracer line is run alongside the probe and contained in an insulated jacket. Steam tracing is preferred where electrical service is unavailable or where the plant already runs an extensive steam tracing distribution.

Power Calculation Quick Reference

For an insulated 1" OD probe at 100 °F ambient maintaining 150 °F:

Add 50% headroom for startup, weather, and uncertain insulation R-values.

When to Specify Heating

• Natural gas sampling within 5 °C of hydrocarbon dew point
• Heavy crude / waxy crude sampling
• Sour gas sampling to keep the gland-air interface above the water dew point and prevent SCC
• Bitumen / dilbit sampling
• Cold-weather installations where ambient drops below process dew point

Configure

Open the SPA Configurator, enable the "heated probe" option, and enter the target setpoint temperature and ambient design temperature. The wizard returns the recommended trace power and the resulting bill of materials.