Smooth Approach Orifice for Emissions Testing

Can you provide more information for us please including suitable construction material and dimensions.

What sort of emissions, and what's under test exactly?

This is a sample of what I am looking for I hope to find a unit pulled from service. This is a sample of what I am looking for of a new unit. Inlet Venturi Nozzles SAO SAO nozzles (Smooth Approach Orifice) are designed as inlet nozzles for high flow rate measurement of air - especially when low pressure loss is indicated.  Excellentstability  High accuracy measurement  Minimalpressureloss Product Description Application: Thanks to a high-efficiency pressure recovery design SAO nozzles experience a very low remaining pressure loss depending on the make of the inlet form and the opening angle of the outlet cone. In contrary to other DP-flow ele- ments almost no straight upstream and only short down- stream paths are needed. Following the principles of the Bernoulli equation the mass flow through a SAO is a func- tion of the square root of the DP and density. To achieve high accuracy rates it is recommended to use a flow computer with averaging mode and online evaluation. This way the SAO nozzle can be applied as a calibration standard for critical flow venturi calibration in CVS test benches with an accuracy of ± 0.5% of reading. Construction and Design: As a standard SAO will be manufactured machined me- chanically to achieve the required coarse values and accu- racy. The SAO consists of a machined and polished body with a connection flansh welded on the outlet. It consists of a radial inlet section, a bore in cylinder form and an outlet formed as a cone. Differential-Pressure Measurement: Positive pressure measurement is against atmosphere and negative pressure tapping takes place in the tube wall of the bore cylinder each through one or several single bores. It is recommendable to connect them with a circuit. Materials: Manufacturing of the nozzle body and flanshes is possible in different usual material like Aluminium or Stainless Steel and other special materials. Material Certificates: Material certificates i.e. according to EN 10204 can be supplied for the used materials. Calibration: Any SAO nozzle should be calibrated from 10% to 100% of the differential pressure range of the specified flow rate. In case of calibration a factory or DAkkS calibration report will be supplied with.  Specifications Nominal Pressure: PN 6 up to PN 16 Nominal Diameter: DN 10 up to DN 500 Bore Diameter d: The calculation of the bore diameter will be done from the supplied data considering the relevant standards like DIN ISO EN 5167 and regulations like VDI/VDE2041and is part of the scope of deliveries. Pressure Loss: The pressure loss depends on the opening ratio and the opening angle and is approx. 10-25% of dP. Pressure Tap: 12 mm pipe with G1/8"i or acc. customer specification. Identification: On inlet side marked: +, Tag-No., PN, D, d and material. Connection type: The installation takes place with flange at the outlet. Pref- ered connection types are flanshes according DIN. But also different types of flanshes and sealings can be manu- factured according customer specification. Installation: Directly on the intrance of a pipe. Installation Lengths Due to the determined opening angle α (6 ... 12°) of the outlet cone the overall-length depends mainly on the restriction diameter d and the connecting line diameter D. It is normally between 200 and 1200 mm. The open- ing ratio ß = d/D should be within 0,4 and 0,8. Straigth In- and Outlet Section: Minimum requirement 5xD on outlet. Ordering Information Please determine for quotation request  Flow range(s) 4000 CFM or larger  Pipe diameter 18 inch od with flange  Material Stainless steel or 4140 high tensile strength aluminum  Accuracy .5%

Ok, so this looks like it has been copy and pasted directly from a supplier's website.

Can you provide a link to the website for us?

You seem to have found one, are you looking for alternative suppliers?

This company manufactures to order As said in note I am looking for a used or new surplus unit. Used cost of this unit is 1000 $ to 2500 US dollars a new built to order unit is 20 to 30 k 20,000 to 30,000$ dollars you can see why I am looking for a surplus unit.

You may find something online but I don't know what second hand E-bay style or trader websites deal with such a specialised piece of equipment.

Others here on CR4 may know. Hey, have you tried a search on Global Spec?

http://www.globalspec.com/productfinder

Is it critical? Could you use something else or get something machined to a lower tolerance at a local shop?

Do you really expect posters to read all that? If you'd do a bit of work and extract the parts relevant to your query you'd have a chance of a better response.

For a start it's not clear (to me anyway) whether it's an orifice plate or a venturi tube you're looking for. Or if it's just that or associated kit - pipe flanges, instruments etc.

Why does it need to be smooth, etc.? Why does a simple hole in a plate fail to suffice?

According to the specs, he wants to pass 4,000 cfm through an orifice plate inserted in an 18" or larger pipe, then measure the ΔP through it as a measure of it's velocity. At those flow rates there will be too much turbulence and vortex shedding due to the transition across the sharp edges inherent in a simple drilled hole. By specifying a Smooth Approach Orifice the flow is much more laminar and reduces the uncertainty and increases the stability and reproducibility of the measurements.

Agreed (GA), but I was hoping s/he would say it.

I trust that everyone agrees that smooth orifices are best.

Heh.