Isokinetic Probes & Liners

We offer a comprehensive range of precision instruments including isokinetic probes for accurate flow measurement, mercury probes for precise level detection, and gas probes tailored for efficient gas sampling and monitoring. Our pitots measure fluid velocity with high accuracy, while our port accessories enhance functionality and versatility for all your sampling needs.

Isokinetic Probes & Liners

Probe Assembly

The main components of a probe assembly:

Probe Heater: Removable rigid tube heater with coiled heating element, electric thermal insulation and thermocouple, with a maximum recommended temperature of 260°C (500°F).
Probe Sheath: 25.4 mm (1 in.) OD tube with quad-assembly attached that includes a replaceable, modular S-type pitot tube, stack thermocouple and a 1/4 in. OD stainless steel tube to collect gas samples for Orsat analysis.
Small Parts Kit: Fittings to attach the nozzle to the probe assembly. Fittings include 5/8 in. bored union, nut, and ferrules.

Probe Heater: For accurate results, the sample temperature should remain in the range of 120ºC ± 5ºC (248ºF ± 9ºF) as it travels through the probe. Exposure to elevated temperatures can damage the insulation and shorten the life of the heater. The maximum recommended stack exposure temperature for probe heaters is 260ºC (500ºF). Partial probe heaters are recommended for temperatures above 260ºC (500ºF).

Probe Liners: Standard probe liners are constructed from 5/8 in. OD tubing and have #28 ball joints with an O-ring groove. Available liner materials are borosilicate glass, quartz, stainless steel, inconel, and PTFE. You will need a ball joint adapter if you have a PTFE liner, straight liner, or liner with integrated nozzles. We also offer glass and quartz liners with a male 14/35-inch taper joint for attaching to the appropriate nozzle, eliminating the need for the 5/8-inch union.

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Mercury Probes

PS 12 and Method 30B Probes come in standard lengths of 4’, 6’ and 9’. Appendix K Probes are constructed from Alloy C276 for long-term use in extremely corrosive conditions. Type-K thermocouples are used to monitor, trap, stack, and probe temperatures. Method 30B Probes come standard in stainless steel with Type-K thermocouples to monitor trap and stack temperatures. Both probes are designed for two, 10 mm diameter traps (smaller trap adapters also available). The paired sorbent traps are inserted at the inlet end of the probe, using leak-tight compression fittings before inserting directly into the flue gas stream.

The probe is heated to prevent any liquid condensation in the sorbent traps. An insulated, powder-coated aluminum probe head enclosure minimizes condensation at the junction between the probe and the heated umbilical/sample line.

All probes come with type-K thermocouples and insulated junction enclosures. Standard lengths are available from 4 to 12 feet. Custom lengths are available upon request.

Gas Sampling Consoles

Air Cooled Mercury Sampling Probes

For use in high-temperature stack gas environments, Apex Instruments HGPA Air-cooled probes feature a 2-inch stainless steel or Hastelloy alloy outer sheath as standard, individually controlled heat zones and integrated stack, trap, and probe thermocouples.

Alloy C276 & Stainless Steel Mercury Sampling Probes

Mercury probes come in both single- and dual-heater configurations to keep the sample gas above the dew point and prevent condensation forming in the sample and on the sorbent traps. Dual heater configurations are recommended for PS-12B or other long-term sampling applications where one heater heats the traps and the second heater heats the external portion of the probe outside of the stack. In short-term sampling applications such as 30B and RATA sampling, single heater probes utilizing only the trap section heater may be used. All probes come with type-K thermocouples and insulated junction enclosures. Standard lengths are available from 4 to 12 feet.

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Gas Probes

Gas Sampling Probe Assemblies are used for Instrumental Reference Methods. They incorporate the popular heater design from Method 5 probes so liners can be changed in seconds without disturbing the heater. The separate heater tube provides even heat distribution and isolates the electrical elements from the liner. The probe sheaths are constructed with a 2-inch stainless steel outersheath with a tube nut welded to the end for attachment to a porous filter or a bored cap. Probes are available in any length from 2-foot to 20-foot. The probes are manufactured to accommodate standard wattages or customized for hotter conditions. Add “V” to end of part number for 240 VAC.

All IRM Probe Assemblies are available with 1-inch or 2-inch outer diameter stainless steel sheath, 2-inch outer diameter stainless steel sheath with a heater, and a liner made from stainless steel, Inconel, quartz, or glass (120 VAC at 60 Hz). Classic 1-inch outer diameter stainless steel sheath is also still available.

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Pilots

Pitot tubes are used to measure the gas velocity. When the pitot is faced into the gas stream the pressure difference between the two ports equates to the velocity pressure. This differential velocity pressure is measured with liquid manometers or electronic pressure transducers to calculate flow rates.
Apex offers a variety of pitot tubes for your sampling needs including S-Type, Standard, 2D/3D, Modular and Method 2C.