Pressure dependent flow elements
Measuring orifices, nozzles and venturi tubes – overview
Subcritically operated pressure drop devices work according to Bernoulli’s principle and are designed and manufactured according to the international standard DIN EN ISO 5167. They are differential pressure transducers for the measurement of the average flow rate and the mass flow.
Pressure drop devices with suitable differential pressure transducers are used for flow measurements of liquids, gases and vapours in pure phase in pipelines. Since transducers have no movable parts and require hardly any maintenance, this reliable procedure is used preferably in chemical and technical processes.
Main Features
- Throat diameter d of 5 up to 500 mm
- Diameters of DN 10 up to DN 500
- Straight outlet: min. 2 x DN
- Connection by flanges
- Suction operation for free suction of atmosphere
- Quick response time and good accuracy
- Very good long-time stability, no moving parts
SAO Inlet nozzle
SAO nozzles (Smooth Approach Orifice) are inlet nozzles for free suction of air. They are first choice with applications, where only a low pressure drop may occur during the measurement. They are designed according to VDI/VDE 2041 similar to standard Norm DIN EN ISO 5167 part 3.
SAO nozzles are suitable for the measurement of large flows of air at free suction of atmosphere, particularly if short total lengths and low remaining pressure drops are required. Due to their efficient pressure recovery they have a very low remaining pressure drop. It depends on the type of inlet and the outlet cone.
| Property | Functionality |
|---|---|
| Material | Aluminum / Stainless Steel |
| Operating Pressure Range |
Std. approx. 1 - 20 mbar; Custom configuration possible |
| Nominal Pressure | PN 6 to PN 16 |
| Nominal Diameter | DN 10 to DN 500 |
| Constricted Diameter d | Individually customized to the requirements calculated considering relevant standards such as DIN ISO EN 5167 and regulations such as VDI/VDE 2041 |
| Pressure Loss | Permanent pressure loss, depending on opening ratio and angle of the diffuser approx. 10 - 25 % of operating pressure |
| Extraction Nozzle | Std. 12 mm nozzle with G1/8" or as specified |
| Labeling | Type plate on the flow side with: S/N, PN, D, d, and material |
| Installation | Directly at the entrance of a pipeline |
| Installation Lengths | Mainly dependent on connection diameter D at the outlet.The opening angle α of the outlet cone is set (6 ... 12°). The length is usually 200 to 1200 mm. The opening ratio β=d/D should be between 0.4 and 0.8. |
| Straight Inlet and Outlet Lengths |
Open suction, min. 5 x D outlet |
H800 Classic venturi tubes
Classic venturi tubes H800 are manufactured according to standard DIN EN ISO 5167 part 4 with flange connection or for welding. They are the first choice for the flow measurement of gases, vapours and liquids, when short length and low pressure drop are required.
Compared with other differential pressure transducers according to ISO 5167 clearly shorter straight inlet/outlet sections are required. In addition, the weight of big venturi tubes completely manufactured of sheet steel is clearly lower than the weight of comparable venturi nozzles. The remaining pressure drop is approx. 15 up to 20 % of the measured differential pressure.
| Property | Functionality |
|---|---|
| Material | Aluminum / Stainless Steel |
| Operating Pressure Range |
Std. approx. 1 - 20 mbar Custom configuration possible |
| Nominal Pressure | PN 6 to PN 400 |
| Nominal Diameter | DN 50 to DN 1000 |
| Constricted Diameter d | Individually customized to the requirements calculated considering relevant standards such as DIN ISO EN 5167 and regulations such as VDI/VDE 2041 |
| Pressure Loss | Permanent pressure loss, depending on opening ratio and angle of the diffuser approx. 5 - 15 % of operating pressure |
| Extraction Nozzle | Std. 12 mm nozzle with G1/8" or as specified |
| Labeling | Type plate on the flow side with: S/N, PN, D, d, and material |
| Installation | Between flanges and welded in horizontal, vertical, or angled pipe lines. |
| Entry Lengths | Mainly dependent on the constrictiondiameter d. The opening angle α of the inlet and outlet cones is set. The length is usually between 250 and 5000 mm. Referring to an average opening ratio β = 0.6. |
| Straight Inlet and Outlet Lengths |
Min. 2.5 x D inlet and 1 x D outlet |
Main Features
- Throat diameter d of 10 up to 800 mm
- Diameters of DN 25 up to DN 1000
- Straight inlet/outlet: min. 2.5 x DN / 1 x DN
- Connection by flanges or welding
- Vacuum or pressure operation
- Quick response time and good accuracy
- Very good long-term stability, no moving parts
Main Features
- Throat diameter d of 10 up to 800 mm
- Diameters of DN 25 up to DN 1000
- Straight inlet/outlet: min. 4 x DN / 2 x DN
- Connection by flanges or welding
- Vacuum or pressure operation
- Quick response time and good accuracy
- Very good long-term stability, no moving parts
DV700 Standard Nozzle
Standard nozzles DV700 are manufactured according to standard DIN EN ISO 5167 part 3 with flange connection or for welding. They are the first choice for the flow measurement of gases, vapours and liquids, when short length and low pressure drop are required.
Compared with other differential pressure transducers according to ISO 5167 clearly shorter straight inlet/outlet sections are required. In addition, the weight of big venturi tubes completely manufactured of sheet steel is clearly lower than the weight of comparable venturi nozzles. The remaining pressure drop is approx. 15 up to 20 % of the measured differential pressure.
| Property | Functionality |
|---|---|
| Material | General construction steels RSt37-2 Stainless steels 15Mo3 Unalloyed quality steels C22.8, X6CrNiTi1810 Heat-resistant construction steels 16Mo3 Plastics (PP, PVC) 13CrMo45 |
| Operation Pressure Range |
Std. approx. 1 - 20 mbar Custom design possible |
| Nominal Pressure | PN 6 to PN 100 |
| Nominal Diameter | DN 50 to DN 800 |
| Constricted Diameter d | Individually calculated based on your requirements considering relevant standards such as DIN ISO EN 5167 and regulations such as VDI/VDE 2041 |
| Pressure Loss | Permanent pressure loss, depending on opening ratio β=d²/D² approx. 10 - 15 % of working pressure |
| Extraction Nozzle | One nozzle at the inlet and at the narrowest cross-section. More than 2 nozzles or flushing connections are also available upon request. |
| Labeling | On the outer Ø of the nozzle according to DIN 19205, additionally with batch number and inspection stamp. |
| Version A | End flanges pushed on and welded tight. Application up to max. 300 °C. Negative pressure extraction via a ring chamber. |
| Version B | End flanges pre-welded. Radiographic testing of the circumferential seams possible. Application up to max. 450 °C. Minus pressure tapping as single borehole. |
| Accessories | Condensate traps and shut-off valves welded on or supplied loose on request |
MBL500 Orifice measuring section
Orifice measuring sections are manufactured with different differential pressure transducers as orifices or nozzles with firmly connected inlet/outlet tubes for usage even with high pressures and temperatures according to standard DIN EN ISO 5167 part 2 and 3. They meet the minimum requirements of straight inlet/outlet lengths and mechanical type according to the standard.
They are used as differential pressure transducers for the flow measurement of gases, vapours and liquids especially in small pipes up to DN 100. Exact calculation values for the flow will be provided by using calibrated sections. In addition, the possibility of replacement of the measuring module allows for an easy changing of the measuring range.
| Property | Functionality |
|---|---|
| Material | Manufacturing in various materials and special materials possible. In particular, in the case of high temperatures and aggressive media, the specific application case must be assessed. |
| Material Tests |
Upon request, certificates for the materials used can be provided, e.g., according to EN 10204. |
| Operating Pressure Extraction |
The operating pressure is extracted at a distance a1 and a2 from the diaphragm plate. There is a distinction between flange pressure extraction according to DIN 19214 and DD/2 pressure extraction in the pipeline, where a1 equals the pipeline diameter D and a2 equals D/2. In special cases, the operating pressure extraction can be norm-like as a corner extraction at the flange. |
| Operating Pressure Range |
Std. approx. 1 - 20 mbar; Custom design possible |
| Nominal Pressure | PN 6 to PN 100 |
| Nominal Diameter | DN 10 to DN 200 |
| Constricted Diameter d |
Individually calculated based on the requirements, considering corresponding standards such as DIN ISO EN 5167 and regulations such as VDI/VDE 2041. |
| Pressure Loss | Permanent pressure loss, depending on the opening ratio d:D approx.30 - 80 % of the effective pressure |
| Extraction Nozzle | Std. 12 mm nozzle with G1/8"i; or as specified |
| Labeling | S/N, PN, D, d, flow direction, and identification of the extraction nozzles by + and - |
| Installation Type F | Between flanges / welded in horizontal, vertical, or angled pipe lines. |
| Installation Type S | For welding into the pipe lines. Dimensions as MBL 500F. |
| Installation Note | Counter flanges, screws, and seals are not included in the scope of delivery of a measuring section. For the seals, the regulations regarding the medium and operating conditions must be observed. Seal type: smooth, recess DIN 2513 or groove DIN 2512. |
| Installation Lengths | depending on nominal diameter approx. 50 to 4000 mm |
| Straight Inlet and Outlet Lengths |
Min. 2.5 x D inlet and 1 x D outlet |
| Possible Accessory | Counter flanges, screws, and seals for installation, shut-off valves, condensate vessels, measuring line vessels, and valve blocks... |
Main Features
- Bore diameter d of 5 up to 160 mm
- Diameters of DN 10 up to DN 200
- Straight inlet/outlet: min. 10 x DN / 5 x DN
- Connection by flanges
- Vacuum or overpressure operation
- Quick response time and good accuracy
- Very good long-term stability, no moving parts
Accessories
We also offer further measurement technology accessories for flow measurement. In addition to suitable sensors for the measuring section, complete evaluation units for plug-and-play measurements are also available.