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Pomfret, MD 20675
Phone: (301) 934-5605
Fax: (301) 934-5606
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EPRI Isokinetic Sampling Nozzles (Probes)
for Liquids and Gases, including Water, Steam, and Natural Gas
Isokinetic sampling nozzles (probes) for sampling gases and liquids (including steam and water in steam plants). Ideal for saturated
steam, superheated steam, and water sampling. Other applications include oil in water, water in oil, propant in oil, and sand
These Nozzles meet the requirements of ASTM Standards D1066 and D3370.
For superheated steam applications, it is not recommended to install the Nozzle in locations where the steam temperature is not at
least 100F above the saturation temperature.
It is not recommended to install the Nozzle immediately after desuperheaters, in locations
where there are large temperature changes, or where there is high carry-over of sodium hydroxide. Where these conditions exist,
there should be more frequent inspection of the Nozzle, Nozzle attachment, valves, and welded tubing up to the primary cooler. If
installed downstream of desuperheating sprays, the Nozzle location should be far enough downstream where complete mixing has occurred.
Pressure range: subatmospheric to 5000 psig (34.5 MPa)
Temperature range: Up to 1200ºF (650ºC)
flange or welded to process pipe
Sampling gases and liquids for on-line and grab sample chemical analysis can be a major source of errors. Up to several orders
of magnitude concentration changes of dissolved and suspended impurities have been observed when sample withdrawal, cooling, or transport
are not properly performed. Multi-port Steam Sampling Nozzles (Probes) are rarely used because of their complexity, cost,
non-isokinetic characteristics, and problems with use in large pipes and they are no longer a part of the ASTM D1066 standard.
more appropriate and functional design was developed and the design and performance of these nozzles was verified in the Electric
Power Research Institute (EPRI) research project RP2712-8. This design was then included in ASTM D1066, "Standard Practice for
Sampling Steam". Additional information about the need for isokinetic sampling and the proper design and operation of a sampling
system can be found in a technical article entiled "Sampling Savvy".
A typical Weld-in Nozzle (probe) design is shown in Figure 1 and Flanged Nozzles are shown in Figure 2. The nozzles extract
a representative isokinetic sample from a flow region removed from the pipe surface and at the average flow velocity of the sample
fluid. This arrangement results in the withdrawal of the sample with representative concentrations of dissolved, suspended,
and volatile constituents.
An appropriate nozzle (probe) is designed for the desired sample flow and typical conditions of the sample
fluid. When the flow velocity through the pipe changes, sample flow should be adjusted to maintain isokinetic sampling.
Nozzle (probe) is designed with considerations of vortex shedding, resonance, vibration, erosion, and strength of the attachment to
Note: Sample flow rate and velocity, tubing size, distance to primary cooler, pressure drop through the system, etc.
should all be considered when designing a sampling system. For more information, please visit our Sampling System Design page.
Jonas, Inc. recommends the use of A182-316/316L SS because of the material's resistance to corrosion and erosion. Other materials
are available upon request.
Superheated Steam Sampling
Installation, operation, and inspection of the Nozzle is the responsibility of the user and should be in accordance with all applicable
Codes and Procedures.
Figure 2. EPRI Isokinetic Sampling Nozzles (Flanged Design)
Figure 1. EPRI Isokinetic Sampling Nozzles (Weld-in Design)
Serving the power industry since 1983
Specializing in Sampling and Instrumentation, Corrosion,
Water and Steam Chemistry, and Failure Analysis