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FAQ – VPFlowScope M

In this section, you can find most answers to common questions about the VPFlowScope M 3 in 1 mass flow meter. Do you miss somthing? Other questions? Please contact us and we will be happy to help you further.

Can you use a 35 bar flow meter in a 40 bar system?

From a safety perspective: yes. We tested our products well above 40 bar. however, the pressure sensor in the VPFlowScope cannot measure higher than 500 psi (which is  a little more than 35 bar). Above this, the sensor will start to behave non-linear, and it will eventually clip. For further details, please check the safety guidelines for the VPFlowScope 40 bar version in the user manual.

What is the recommended installation length for a flow meter?

VPInstruments’ flow meters are calibrated on our proprietary pressurized calibration system, which is unique in the world. Pressurized calibration has many advantages. One of the main advantages is that the calibration conditions are nearly identical to the process conditions in the field. This minimized the total measurement uncertainty. To phrase it simply: It is as accurate as you can get, as long as the flow profile is fully developed and symmetric.


Distorted flow profiles

The flow profile in the pipe is probably the biggest enemy to your flow meter’s field accuracy. Pipe bends, elbows, diameter changes, valves will distort the flow profile in the pipe. As the flow meter measures only on one point in the pipe, it cannot “see” these distortions. The flow meter calculates with the ideal, symmetric, fully developed profile.


Distorted flow profiles can lead to large measurement errors. So what is the trick: keep enough upstream length before the flow meter and downstream length after the meter. In flow meter terms, we use the term “ X times D” to specify this length. And the X depends on the type of upstream/downstream object. It does not depend on the type or brand of insertion flow meter, as long as it is a single point meter. Only so called “flow conditioners” can reduce the required length.


Extensive research has been carried out by various labs, and this has lead to a “generic” table with common upstream and downstream objects. You can find this table below, as wel as in our user manuals.


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Ok, but what happens if you are not able to fulfil these requirements? Well, that depends on the application. If it is just trending, you can decide to install the flow meter, but be aware of the additional uncertainty. We can also offer you a CFD simulation if you have a better idea about the flow conditions in the pipe. Contact us for details.


My VPFlowScope DP shows a value under the Qmin (minimum) value

How is this possible? The DP has a specified Qmin of 20 mn/sec. Below this value, it is still possible to see flow values, because if internal averaging of the meter and due to the way it is calibrated. During calibration, we set the internal cutoff on 15 mn/sec, which enables you to see fluctuations around 20 mn/sec.




How does the alarm option on the VPFlowscope M work?

The VPFlowScope M features an alarm option for condition monitoring. This alarm option can be configured with VPStudio. Upper, lower or a combination of these boundaries can be set as a condition level. To which of the 3 measurements the alarm is connected is up to the user. One of 3 can be chosen with the preferred unit, e.a.: m3n/hr, bar, SCFM, deg F, Kelvin, and many more.

Download the full application note here: 

How do I connect the VPFlowScope to a Modbus RS485 network?

All VPFlowScope mass flow meters are equipped with a Modbus RTU interface. This makes connecting to a modbus RS485 network very easy, provided that you are an experienced modbus user. If not, please visit to read more about the basic principles. Or read this application note.


Is modbus RTU always included in your flowmeters?

Yes, of course! Modbus RTU is included. All our flow meters are equipped with Modbus RS485 and use the Modbus RTU protocol. The new VPFlowScope M even has Modbus/TCP. So why use old-school 4 … 20 mA when you can have all parameters at once via Modbus?

Further reading on how to connect to a modbus network can be found here.

What type of connections are possible with VPVision?

VPVision offers 8 analog inputs & 1 modbus RS485 input,  to connect 1 daisy chain up to 8 sensors hard-wired directly to the VPVision main cabinet. When VPVision is part of an industrial Ethernet network, you can connect additional sensors using our I/O modules. This saves you significantly on installation and wiring costs.  You can choose from the following I/O modules:
• Modbus extension module with power supply
• Modbus to Ethernet converter with power supply, for RS485 based sensors
• Analog to Ethernet module with power supply, for 4 … 20 mA sensors
• Modbus and analogue to Ethernet module with power supply, to combine both 4 .. 20 mA and modbus based sensors

The Ethernet based I/O modules enable you to overcome great distances in the factory without a lot of wiring. The main VPVision unit also offers 4 LAN ports on the PC. Lan 1 is used to configure the system. The Other LAN ports can be used to connect to the company network, to connect a 3G module or to connect a subnet with I/O modules.

What are the benefits of VPVision Energy Monitoring?

VPVision is unique in it’s class. The Web-Based software offers real-time monitoring of all utilities.
You can view your energy consumption live on anywhere, anytime. On PC, Tablet or smartphone

  • SQL Database
  • Flexible and scalable
  • Easy to use interface
  • Limitless in amount of connected sensors
  • Virtual channels
  • Alarms and reports send by email
  • Third party data base connection (SQL)
  • Open for third party sensors
How can I access VPVision?

VPVision energy management software can be accessed in multipe ways: Ethernet, 3/4G, Wi-Fi, VPN. Your energy data is available anytime, anywhere. In Real-time.

Connecting the VPVision system to a client’s Ethernet will enable everyone, provided they connect to the same network, to access VPV by using the fixed IP-address with any laptop, tablet or smartphone.
VPN (Virtual Private Network) connection.
This will enable users to access the VPVision system from anywhere in the world with a username & password. This is also a very fast and easy way to provide remote support.
Via 3/4G module
Connect a 3/4G module to the VPVision will allow you to access the system from anywhere in the world. The difference between this method & VPN connection is that this does not require the VPVision system to be connected to the customers Ethernet. Additional costs will occur due to use of local network.
Via Wi-Fi
Connect a Wi-Fi module to the VPVision system allows you to access the VPVision software wirelessly within close range of the WiFi module. Please note this would also be possible when connected to the Ethernet of the customer and you are connected to the same network with WiFi. Use the exisitng infographic in leaflet!”

How can i integrate VPVision with the exisiting BMS/PLC/SCADA?

VPVision can be integrated with your exisiting system with the optional SQL module, offering you the last hour data to your master system.

How can I download data from VPVision?

With the CSV widget you can extract data in CSV format. The CSV export wizard can be pre-configured, which makes easy, consistent download of data a very easy task.

How can I expand the VPVision energy management system?

VPVision is easy to expand. We can add sensors to your existing or new hardware and the software can also be easily expanded with optional items and additional sensors. We can update the software remotely. You can also use existing sensors with 4 … 20 mA signals. VPVision grows and adpats according to the needs of your company.

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