Current position > News detail
『Low Pressure Drop Flow Meter Selection: Comparing Annubar vs Vortex Tech for Large Mainline Efficiencies』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
Low Pressure Drop Flow Meter Selection: Comparing Annubar vs Vortex Tech for Large Mainline Efficiencies
Quick Answer: For large mainline efficiencies above DN250, an Annubar averaging pitot tube usually gives lower permanent pressure loss and lower installed cost than an inline vortex meter. For smaller lines from DN15 to DN200, vortex meters are often the simpler and more direct choice. Send your pipe size, fluid, pressure, temperature, and flow range to Silver Automation Instruments and we will help you pick the right meter for your mainline.
Why Pressure Drop Changes the Real Cost
Many engineers compare meter price only. Here is the thing. A meter with high pressure loss adds running cost every day. For a DN400 natural gas line at 10 bar in Indonesia, an extra 0.3 bar loss can push the upstream compressor harder. The energy cost shows up month after month. On a long water main in Peru or a steam header in Chile, the same rule applies.
Low pressure drop matters most in gas, steam, and large water networks. A small loss at 20 bar may not seem like much, but it reduces line capacity. Silver Instruments has seen many projects where the meter was cheap but the operational cost was not.
Annubar Flow Meter Basics and Where It Fits
Annubar uses a multi point averaging pitot tube inserted into the pipe. It measures differential pressure and needs a separate DP transmitter. Most installations use a 4-20 mA HART transmitter with square root extraction. Because the probe blocks only a small part of the cross section, permanent pressure loss is often below 0.1 bar on DN300 to DN1200 lines.
Annubar works well on clean natural gas, saturated steam, superheated steam, and clean liquids. It does not like dirt, wax, or slurry. The sensing holes can plug. It also needs a good velocity profile. If you have a short straight run, add a flow conditioner or choose another meter type.
Vortex Flow Meter Basics and Where It Fits
Vortex meters use a bluff body to generate vortices. The meter reads frequency and converts it to flow. Output can be 4-20 mA HART, pulse, or Modbus. Vortex meters are common for steam, compressed air, and clean water in DN15 to DN300 lines. They do not need impulse lines or a separate DP transmitter.
Above DN300, inline vortex meters get heavy and expensive. The bluff body also creates more permanent pressure loss. On a DN300 saturated steam line at 12 bar, vortex loss can be 0.2 to 0.5 bar. That is okay for a local boiler house. It is often too high for a long transmission line.
Direct Comparison on Large Mainlines
On a DN600 natural gas line at 18 bar, an Annubar may lose 0.03 to 0.08 bar. A vortex meter for the same line would be very heavy and can lose 0.3 bar or more. Most engineers choose Annubar at this size. On a DN100 steam line, the picture reverses. A vortex meter installs quickly and gives a direct signal. An Annubar on DN100 adds a DP transmitter and impulse tubing for little benefit.
The crossover size is usually between DN200 and DN300. Below that, vortex is easier. Above that, Annubar or another insertion technology wins on both cost and pressure loss. The final call depends on fluid condition, pipe run, and whether you can maintain impulse lines.
When Annubar Wins in Real Applications
Annubar wins in gas turbine fuel lines, boiler steam headers, and large water mains. A customer in Indonesia measured natural gas to a gas turbine on a DN750 line a
Silver Instruments supplies the DP transmitters, pressure transmitters, and paperless recorders that pair with Annubar primary elements. For a DN600 steam header, we often size a DP transmitter with 4-20 mA HART output and a pressure transmitter for temperature and pressure compensation.
When Vortex Wins in Real Applications
Vortex wins on smaller lines and local measurement points. In a Vietnam textile factory, a DN80 vortex meter on compressed air gave a direct pulse signal to the PLC. No square root extraction was needed. In a food processing plant in Thailand, a DN100 vortex meter on saturated steam provided mass flow data in kg/h when combined with a pressure transmitter and a PT100 temperature sensor. The total installed cost was lower than an Annubar plus DP transmitter.
For clean steam or gas where the line is DN50 to DN200, Silver Instruments often recommends a vortex meter. The meter is compact, has no impulse lines, and maintenance is straightforward.
How to Size and Specify Without Mistakes
Start with line size and fluid phase. For DN15 to DN200 liquid or gas, check vortex first. For DN250 to DN2000 clean gas or steam, check Annubar. For conductive liquids in any size, an electromagnetic flow meter may be better. For large dirty water or sludge, ultrasonic or electromagnetic is often safer.
Do not forget the straight run. A vortex meter typically needs 15D upstream and 5D downstream. An Annubar may need 10D to 20D upstream depending on the model and flow profile. Most engineers skip this part. We have seen this on customer sites many times. If the straight run is short, move the meter or install a flow conditioner. No transmitter can fix bad installation.
FAQ
Which meter has lower pressure drop, Annubar or vortex?
Annubar generally has lower pressure drop on DN300 and larger lines because it is an insertion probe. Vortex meters have a bluff body in the flow path. On large gas lines, Annubar loss is often below 0.1 bar while vortex loss can be 0.3 bar or more.
Can I use an Annubar on a DN100 line?
Yes, but it is not always the best choice. On DN100, a vortex meter is easier to install and maintain. Annubar is more attractive on DN250 and above where the cost and pressure loss advantages grow.
What output signals do these meters provide?
Annubar needs a DP transmitter, usually 4-20 mA HART with square root extraction. Vortex meters can output 4-20 mA HART, pulse, or Modbus directly. Some vortex meters also include pressure and temperature compensation for steam mass flow.
Which is better for saturated steam?
For DN50 to DN200 saturated steam, vortex is often better because it is simple and has no impulse lines. For DN250 to DN1000 steam headers, Annubar is often better for low pressure loss. The final choice depends on steam pressure, pipe size, and flow turndown.
How do I request a selection for my flow meter?
Send Silver Instruments your fluid, pressure in bar, temperature in °C, pipe size in DN, and minimum or maximum flow rate. You can reach us by Tel: +86-25-68650347, WhatsApp: +86-25-52155837, or WeChat: +86 15365082610. We will recommend a vortex meter, DP transmitter, or another suitable flow meter.