Sampling probe with static dilution
Gaseous emissions from odor and contaminant point sources are often highly concentrated or have a high moisture content, often making olfactometric and analytical analysis more difficult to achieve. A predilution of gaseous emissions directly at the source, using a pure and dry air supply, is often necessary to avoid the inconveniences associated with moisture condensation or high odor concentrations of the gaseous emissions collected.
The Onose-8® sampling probe, designed and marketed by AtmoDC Inc., allows the dilution of the gaseous samples directly inside the emission source during the sampling procedure. Thus, diluting at the source has the advantage of reducing the concentration of contaminants and odors, as well as avoiding moisture condensation before the sample reaches the sampling bag.
Onose-8® sampling probe can be used for:
- For the sampling of odours or gaseous contaminants;
- For sources with a temperature of release of more than 500 °C and relative humidity of 100%.
This probe has been designed to offer various precise dilution ratios as well as robustness and ease of use. The Onose-8® sampling probe has been designed according to the criteria of the EN 13725 standard. The sampling probe was designed using Swagelok parts and fittings. This allows mounting and easy disassembly during maintenance, as well as a minimum of leakage between the parts joints.
Applications
The Onose-8® static predilution sampling probe from AtmoDC Inc. is equipped with two ports. The first port, located near the tip of the probe, is inserted into the point source emission in order to collect the gaseous emissions. The second port is connected to a dilution gas source (such as a bag of purified, dry air or nitrogen) used to dilute emissions from the source. Mixing of the dilution gas and the source’s gaseous emissions occurs inside the point source in a specially designed dilution chamber. This minimizes the risk of moisture condensation in the sampling bag, as the temperature of the dilution gas is the same as that of the emissions from the point source. The mixture of gaseous emissions and dilution gas is then collected inside an Onose-8® sampling bag using the Onose-8® vacuum chamber.
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How the sampling probe works
The sampling probe operates through negative pressure (vacuum) induced within the probe. This negative pressure allows the probe to capture the stack air to collect and mix it with the dilution gas (such as purified air). This negative pressure is produced by the Onose-8® vacuum chamber when it is connected to the sampling probe via the vacuum chamber’s O-ring seal. A tube with an outside diameter of 0.25 in (6 mm) can be used to connect the sampling probe to the vacuum chamber.
To collect a stream of stack air, the Onose-8® predilution sampling probe must be inserted into the point source so that the sampling end of the probe, the orifice in the dilution adapter (point A) and the dilution chamber (point B) are fully inserted inside the source. This allows the stack air and dilution gas to mix in the dilution chamber at the same temperature as the airflow of the point source.
The vacuum created inside the sampling probe allows to collect gaseous effluent through the end of sampling probe (point A). The sampling flow rate of the gaseous effluent is determined by the size of the orifice at the end of the dilution adapter (point A). Different ports may be used with the Onose-8® sampling probe.
Each of these orifices has a different diameter, thus allowing different sampling and dilution rates to be obtained.
The dilution chamber of the Onose-8® sampling probe allows the stack air from the point source to be mixed with the dilution gas (such as fresh, odorless air) required for dilution.
Just like the stale air, the fresh air used for dilution is drawn into the sampling probe by the negative pressure generated by the Onose-8® vacuum chamber. An Onose-8® sampling bag filled with fresh air (or nitrogen) is connected to the dilution gas O-ring of the probe using a quick-connect valve (not included with the sampling probe). The flow of fresh air entering the sampling probe is controlled by the dilution gas orifice, allowing a precise stale air/fresh air dilution ratio to be obtained.
The dilution gas and the stack air therefore enter the sampling probe through their respective ports before converging in the dilution chamber, where they are mixed at a known dilution ratio. The accuracy of the dilution rate is ensured by the calibration certificate for the Onose-8® predilution probe and by the probe’s manometer. This manometer allows to measure the negative pressure during sampling.
Knowing the negative pressure inside the probe is important because it allows accurately determining the dilution rate, as indicated on the probe calibration certificate.
Once the stale air/fresh air dilution has been carried out according to a predetermined dilution ratio, the mixture is then directed, by means of the vacuum created by the vacuum chamber, to the manometer and valve. The mixture of stale air and fresh air is then expelled outside the sampling probe through the O-ring of the vacuum chamber. The mixture of gaseous emissions and pure air is transported through a tube with the Onose‑8® vacuum chamber inside an Onose‑8® sampling bag.
Once inside the sampling probe, the odorous gas effluent is directed to the dilution chamber, where the odor will be mixed with the dilution gas supply (purified air or nitrogen) to produce a diluted sample.
For any information pertaining to the purchase of this product, we will be more than happy to talk to you or answer your email. Please use the following address: info@onose.ca
Technical specifications: Sampling Probes
Product Number | ATM-SS-P-600-C-XDIL | ATM-SS-P-600-5KIT | ATM-SS-P-600-XDIL | ATM-SST-P-600-5KIT | ATM-SST-P-600-XDIL |
|---|---|---|---|---|---|
Manufacturer | AtmoDC Inc. | AtmoDC Inc. | AtmoDC Inc. | AtmoDC Inc. | AtmoDC Inc. |
Instrument | Onose-8® Compact Static Predilution Sampling Probe | Onose-8® Static Predilution Sampling Probe Kit with 5 Dilutions | Onose-8® Static Predilution Sampling Probe | Onose-8® Static Predilution Sampling Probe Kit with 5 Dilutions | Onose-8® Static Predilution Sampling Probe |
Length 1 | 600 mm (24 in) | 600 mm (24 in) | 600 mm (24 in) | 600 mm (24 in) | 600 mm (24 in) |
Body Diameter | 3/8 in | ||||
Material | Stainless Steel | Stainless Steel | Stainless Steel | Stainless Steel and Teflon | Stainless Steel and Teflon |
Maximum Temperature | More than 500 °C | More than 500 °C | More than 500 °C | 120 °C | 120 °C |
Nominal Dilution Ratio 1,2 | 1:6 to 1:47, selected at order time |
| 1:2 to 1:80 |
| 1:2 to 1:80 |
Dilution Adapter Type | Fixed, welded to the body | Interchangeable | Interchangeable | Interchangeable | Interchangeable |
Number of Dilution Adapters | 1 (fixed), selected at order time | 5 | 1, selected at order time | 5 | 1, selected at order time |
2 The exact dilution ratio is indicated on the calibration certificate included with the unit
Sampling Probe Components
The Onose‑8® static predilution sampling probe is equipped with a valve, a manometer, and tool-free fittings to connect the probe to the dilution gas supply and the Onose‑8® vacuum chamber, which houses the Onose‑8® sampling bag.
The mixing of dilution gas and the source’s gaseous emissions occurs inside the emission source and is then transported to the sampling bag. Onose-8® sampling bags and Onose-8® vacuum chambers marketed by AtmoDC Inc. are all compatible with the Onose‑8® static predilution sampling probes.
Two types of probes are available in the Onose-8® product range. Both types of sampling probes can withstand relative humidity reaching nearly 100%. Regardless of the type of sampling probe used, the probe’s static dilution ratio can be changed as needed. Dilution ratios offered with the Onose-8® static predilution sampling probes vary between 1:2 and 1:80.
- The sampling probe completely made of stainless steel can withstand temperatures above 500 °C.
- The predilution probe made of Teflon® and stainless steel is easier to handle, is more compact and can withstand temperatures up to 120 °C.
| Part | Name | Function |
|---|---|---|
| A | Dilution Adapter | Adapter used to control the flow rate of the source gas. |
| B | Dilution Chamber | Chamber used for mixing source and dilution gases. |
| C | Manometer | Gauge to determine the internal pressure of the probe during sampling. |
| D | Valve | Allows the sampling probe to be isolated from the vacuum chamber. |
| E | Dilution Gas Port | Port to connect the dilution gas supply to the probe for dilution purposes. |
| F | Sample Gas Port | Port to connect the sampling probe to the vacuum chamber. The diluted sample is extracted through this port. |