Saturday 26 September, 2020

The MASS-VIEW FAQ page displays all frequently asked questions to us and displays the answers.


What is the difference between MASS-VIEW and a VA-meter?

MASS-VIEW® is the digital high-tech alternative to the VA meter or purgemeter. For many industrial processes and chemical plants, Bronkhorst’s MASS-VIEW® eliminates the relative inaccuracy of VA meters, the need to recalibrate for different gases and the safety risk of ruptured glass tubes, at a price directly comparable with the cost of a variable area meter and separate transmitter. For OEMs, it offers the option of incorporating more modern, aesthetic gas flow measuring instruments into their equipment, presenting a more appropriate, high technology image.

The basic advantages of the VA meter are its relatively low cost, reasonable accuracy, simplicity of design, low maintenance and ease of installation. However, one drawback is that flowmeter accuracy degrades when fluid temperatures and pressures fluctuate, whilst there is also a problem of parallax error when taking readings from different viewpoints. In addition, glass and plastic tubes often break in usage, leading to the risk of potentially dangerous gases leaking from the instrument; to compensate, metal tubes and magnetic float sensing are sometimes used instead, but such designs are comparatively expensive, typically double the price.

MASS-VIEW® versus VA-meter



Display Digital OLED display, easy direct or relative reading of actual flow Visual check on glass  could lead to parallax errors
Mounting orientation Any Vertical
Measured flow Mass flow Volume flow
Insensitive for temperature and pressure variations YES NO
Flow path Aluminium Glass or plastic
Output signal 0-5V and RS-232 and Modbus-RTU No signal
Alarms Standard available with 2 relays Separate transmitter needed
Media Standard 7 gases available One gas or one liquid
Accumulated flow rate display Standard totaliser available in several units readable Not displayable
Rangeability 1:100, 4 pre-installed full scale ranges 1:10, one full scale range

What is Aeration?

Aeration is a process which circulates mixes or dissolves air (or other gases) in a liquid or other substance. Aeration Liquid

Industrial sectors:

• Ice Cream / Whipped Cream

• Beverage

• Soil

• Waste Water Treatment

• Fermentation

• Fish or algae farms

Application requirements:

• High repeatability

• Robustness

• Dirt resistivity

• Easy to check actual flow

• Gas totalization

What is the amount of flow at a certain fore pressure ?

This form can help you calculate the flow which can be reached at a certain fore pressure (assuming back pressure is atmospheric).
Just select which gas will be used and what fore pressure.

How to change the flow unit of a mass flow meter (MASS-VIEW)?


It is very easy to change the flow unit of a MASS-VIEW mass flow meter.

  • Press the navigation push button under the MASS-VIEW display.
  • The Main menu will appear.
  • Push ‘down’ on the navigation button to the measure menu-item and press ‘enter’.
  • The Measure menu will appear.
  • Push ‘down’ on the navigation button to the unit menu-item and press ‘enter’.
  • Now you can select 26 different engineering flow units by pressing ‘down’ or ‘up’.
  • Select the one you need and press ‘enter’.
  • You can return to the main screen by selecting the menu-item back several times.

This video will demonstrate the change of a flow unit on MASS-VIEW.

Can MASS-VIEW be used at sub-atmospheric pressure conditions?

Our MASS-VIEW mass flow meters are specified from 0 bar(g), below 0 bar(g) (sub-atmospheric pressure condition) we expect a lower accuracy than specified in the datasheet.

Calibration Interval

Mass flow instruments, in fact all process instruments, experience wear from the conditions of the process in which they are installed. Temperature, electronic component tolerance shift, contamination build up over time (even very slight), plus other factors will all contribute to affecting the accuracy of an instrument.

Your instruments should regularly undergo, at a minimum, a calibration check if not a recalibration. But how often? Because the nature of each application is different (conditions, running time, etc.) a calibration can last three years or three months.

Bronkhorst® instruments do not have specified due dates for calibration. Bronkhorst® suggests that our instruments be calibrated every year. However based on the application conditions, and perhaps company quality procedures, each customer must determine when they need to send in an instrument for recalibration.

Properly calibrated instruments will be more accurate, more reliable, help ensure consistency, and help improve production yields.

Is the MASS-VIEW bidirectional?

No, the MASS-VIEW has only one flow direction. From bottom to top of the instrument, on the backside of the instrument an arrow shows the correct flow direction

Is there a pressure drop chart of the MV-400 series controller available?

For the models: MV-401, MV-402, MV-404
Min. ΔP : 1 bar(d)
Max. ΔP : 7 bar(d)

For MV-405
Min. ΔP : 2 bar(d)
Max. ΔP : 7 bar(d)

Because of the internal spring it takes a minimum ΔP of 1 bar(d) (2 bar(d) for the MV-405) to control the output flow.
The pressure loss is minimal because of the internal spring and membrane.

IP Rating and NEMA Rating


The IP Rating (Ingress Protection Rating) of an instrument consists of the letters IP followed by two digits and an optional letter.  As defined in international standard IEC 60529, it classifies the degrees of protection provided against the intrusion of solid objects including body parts like hands and fingers, dust, and accidental contact (the first digit after IP), and water (the second digit after IP) in electrical enclosures. IP Rating Chart
The National Electrical Manufacturers Association (NEMA) in the United States also publishes protection ratings for enclosures similar to the IP rating system published by the International Electrotechnical Commission (IEC). NEMA however also dictates other product features not addressed by IP codes, such as corrosion resistance, gasket aging, and construction practices. NEMA Rating Chart
For this reason while it is possible to map IP Codes to NEMA ratings that satisfy or exceed the IP Code criteria, it is not possible to map NEMA ratings to IP codes, as the IP Code does not mandate the additional requirements. IP to NEMA

How to connect several MASS-VIEWs to a RS-485 bus system?

MASS-VIEW® instruments have digital communication possibilities.


  1. a point to point connection to a PC (see FAQ: How to connect MASS-VIEW® using RS-232 to a computer?) or
  2. a RS-485 bus system using Modbus. Connecting this way makes it possible to read-out all instrument on one bus with a personal computer.
For an example of method 2 see the system overview below.
Example of MASS-VIEW on RS-485

In this situation, two seperate power networks are shown isolated by the RJ-45 Power Isolator, only the two datalines are connected between the two networks.

The basis of the RS-485 network is the RJ-45 multiport connector RS-485. An RS-485 network will start with the red begin terminator and will end with the black end terminator. Both are sold as one RJ-45 Terminator Set.
In between are all RS-485 connection cables for MASS-VIEW and one RS-485 USB cable to connect to the PC. To connect the Plug-In PowerSupply for MASS-VIEW to the RS-485 bus, also a RS-485 connection cable for MASS-VIEW is used and there one needs the Y-Adapter cable.
On the PC side, please make sure the correct device driver is installed. This device driver will install an additional (virtual) COM-port on the PC.
The last step is to install software which acts as the master on the RS-485 bus.

What communication possibilities can be used with MASS-VIEW?

MASS-VIEW® has two communication options:

– FLOWBUS over RS-232

– MODBus RTU or ASCII over RS-485

There is no FLOWBUS over RS-485 communication possible.

FLOWBUS over RS-232 is mostly used to communicate directly to a PC (running FLOWDDE + FLOWPLOT). RS-232 is a point-to-point connection.

MODBus RTU or ASCII is mostly used when a fieldbus is used to connect several instruments to one bus.

How to connect 4 MASS-VIEWs using one power supply?

This is an example how to connect 4 MASS-VIEWs to one Plug-in Power Supply (PiPS-MV) using an Y-adapter cable RJ-45 (7.03.241), 5 RS-485 cables for MASS-VIEW (7.03.467) and a RJ-45 multiport connector(7.03.299). This example is only valid as a power supply solution, not for a RS-485 digital network because the terminal set (7.09.214) is missing.

4 MASS-VIEWs powered by one power supply

Is MASS-VIEW compatible with Oxygen (degreased)?

All MASS-VIEW models which have O2 as a pre-installed gas are degreased.

Can MASS-VIEW measure Humid Air?

MASS-VIEW flow meters can measure humid air.

Humid air can be seen as a mixture of water and air. The physical properties of the mixture will differ from those of dry air. Therefore, the inaccuracy of a thermal mass flow meter calibrated for dry air could increase when humid air is applied instead of dry air.

What we have seen is that as long as there is no condensation the inaccuracy caused by humidity is less than 0.1% FS for models MV-104, MV-106, MV-304 and MV-306 and 0.3%FS for models MV-102 and MV-302.

How to connect MASS-VIEW® using RS-232 to a computer?

MASS-VIEW® can be connected to a computer and is able to communicate over RS-232.

Herewith an overview of the right cabling.

  • If you bought the interconnecting cable with loose end then you should arrange a DB-9 connector and mount the wires according to the hook-up diagram which is available in the brochure, manual or on the product information page in the shop.
  • There is also a possibility to order a special RJ-45 male cable to DB9 female which should be connected to a Split-cable (Y) in order to use both power supply and RS-232, see the picture below. If there is no RS-232 DB9 male connector available on your computer, order the RS-232 to USB 2.0 convertor and use the USB port.
  Cable connections
After connecting MASS-VIEW to the computer, you can download and use our Free software to readout the instrument(s)

How to set mass counter units in MASS-VIEW?

It is currently not possible to set the counter units in the MASS-VIEW to use “mass” units (ug, mg, g, kg) using the menu. There is a “work around” by setting this parameter using a Windows PC with RS-232 or USB.

This is the procedure how to do this.

Your Question:

Customer can not read the Counter unit in mass flow


Change the sensortype of the instrument using FlowDDE ( parameter 22 from 131 into 130).

Action to take:

–change parameter 22 from value 131 to value 130:–

Connect instrument to a Serial Comm port of a PC.

– Install FlowDDE Software

– Make FlowDDE connection with the instrument and write/read values by FlowDDE server menu “Test FLOW-BUS and DDE F6 “.

Select the parameter number by the dropdown menu or by entering the number in the box, select read or write as described.

–change parameter 22 from value 131 to value 130:–

– Parameter 7 (initreset)     –> Write value 64 (Soft will enable writing parameter 22).

– Parameter 7 (initreset)     –> Read parameter and check value.

– Parameter 22 (Sensortype)–> Write value 130.

– Parameter 22 (Sensortype)–> Read parameter and check value.

– Parameter 7 (initreset)     –> Write value 82 (NormalRunningMode).

– Parameter 7 (initreset)     –> Read parameter and check value.

Now the Counter value is available in the mass units

What is the sensor principle of MASS-VIEW?

The MASS-VIEW® operates on the principle of direct thermal mass flow measurement. The through-flow design sensor consists of a heater resistor and a temperature sensing resistor and is made of stainless steel. Both resistors are made of temperature sensitive resistive material that is covered with a stainless steel tube. The necessary heating power to keep the temperature difference between the heater resistor and the sensing resistor at a constant level depends on the mass flow. A different and unique heater current is produced for each value of the flow. The measurement principle described is called Constant Temperature Anemometry (CTA).

CTA sensor

The transfer function between mass flow and output signal can be described by the equation:  undefined

Vsignal = output signal
K = constant factor
(includes λ – heat conductivity, Cp – specific heat, μ – dynamic viscosity and ρ – density of the gas)
Φm = mass flow

The working principle is based on King’s law of the ratio between the mass flow and the heater energy. That means the higher the flow, the more energy is required to maintain the chosen ΔT.

The pressure drop over the instrument’s measurement chamber is almost comparable to a straight run of pipe of the same diameter and is thus almost negligible.

Our instruments are suitable for use in the chemical and pharmaceutical industries in mechanical engineering, as well as in gas production.

Based on this concept, mass flow can be measured with low pressure drop, mainly caused by the gas fittings. Compared to traditional thermal MFMs and MFCs with by-pass, the direct measuring MASS-VIEW® is less sensitive to humidity and contamination.


Industries / Applications

» Analytical instruments

» Biogas applications

» Burner controls

» Coating plants

» Exhaust gas measurement

» Gas consumption measurement

» Gas monitoring systems

» N2/O2-generators

» Paint-spray lines

» and more

Alarm settings | What kind of relay is used on Pin 3 and 5?

The MASS-VIEW® flow meter has two alarms connected to a relay/switch. MASS-VIEW Relay 1
This relay is already included in the MASS-VIEW®.
One side of the switch is connected to ground (pin 4, 0 Vdc)  and the other side is connected to Pin 3 (alarm high).






The other relay is also with one side connected to ground (pin4, 0 Vdc) and the other side is connected to Pin 5 (alarm low). MASS-VIEW Relay 2
Please read the manual for more information about the alarm settings you can program.

Switching current 0.5 A, 24 Vdc







Which maximum capacity does a MASS-VIEW® flow meter have?

We have made a maximum capacity list for all MASS-VIEW® models in different flow units.

This table shows the different maximum flow capacities for different MASS-VIEW® models in several flow units. Please note, these capacities are all shown for Air. Use Fluidat on the Net to calculate to other flow units.

MV-101 /

200 mln/min

MV-102 /

2 ln/min

MV-104 /

20 ln/min

MV-106 /

200 ln/min

MV-108 /

500 ln/min


STP conditions are defined in our FAQ

0.2 slm 2 slm 20 slm 200 slm 500 slm @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
200 sccm 2000 sccm 20000 sccm 200000 sccm 500000 sccm @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.4238 scfh 4.238 scfh 42.38 scfh 423.8 scfh 1059 scfh @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.007063 scfm 0.07063 scfm 0.7063 scfm 7.063 scfm 17.66 scfm @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.0001177 scfs 0.001177 scfs 0.01177 scfs 0.1177 scfs 0.2943 scfs @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
214.7 cc/min 2147 cc/min 21470 cc/min 214700 cc/min 536700 cc/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
3.578 cc/s 35.78 cc/s 357.8 cc/s 3578 cc/s 8945 cc/s @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
214.7 ccs/min 2147 ccs/min 21470 ccs/min 214700 ccs/min 536700 ccs/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
3.578 ccs/s 35.78 ccs/s 357.8 ccs/s 3578 ccs/s 8945 ccs/s @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
200 ccn/min 2000 ccn/min 20000 ccn/min 200000 ccn/min 500000 ccn/min @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
3.333 ccn/s 33.33 ccn/s 333.3 ccn/s 3333 ccn/s 8333 ccn/s @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.4549 cfh 4.549 cfh 45.49 cfh 454.9 cfh 1137 cfh @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.007582 cfm 0.07582 cfm 0.7582 cfm 7.582 cfm 18.95 cfm @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
214.7 cm3/min 2147 cm3/min 21470 cm3/min 214700 cm3/min 536700 cm3/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
3.578 cm3/s 35.78 cm3/s 357.8 cm3/s 3578 cm3/s 8945 cm3/s @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
214.7 cm3s/min 2147 cm3s/min 21470 cm3s/min 214700 cm3s/min 536700 cm3s/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
3.578 cm3s/s 35.78 cm3s/s 357.8 cm3s/s 3578 cm3s/s 8945 cm3s/s @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
200 cm3n/min 2000 cm3n/min 20000 cm3n/min 200000 cm3n/min 500000 cm3n/min @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
3.333 cm3n/s 33.33 cm3n/s 333.3 cm3n/s 3333 cm3n/s 8333 cm3n/s @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
15.52 g/h 155.2 g/h 1552 g/h 15520 g/h 38790 g/h
0.2586 g/min 2.586 g/min 25.86 g/min 258.6 g/min 646.5 g/min
0.00431 g/s 0.0431 g/s 0.431 g/s 4.31 g/s 10.78 g/s
0.01552 kg/h 0.1552 kg/h 1.552 kg/h 15.52 kg/h 38.79 kg/h
0.0002586 kg/min 0.002586 kg/min 0.02586 kg/min 0.2586 kg/min 0.6465 kg/min
12.88 l/h or lph 128.8 l/h or lph 1288 l/h or lph 12880 l/h or lph 32200 l/h or lph @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.2147 l/min or lpm 2.147 l/min or lpm 21.47 l/min or lpm 214.7 l/min or lpm 536.7 l/min or lpm @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.003578 l/s or lps 0.03578 l/s or lps 0.3578 l/s or lps 3.578 l/s or lps 8.945 l/s or lps @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
12 ln/h 120 ln/h 1200 ln/h 12000 ln/h 30000 ln/h @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.2 ln/min 2 ln/min 20 ln/min 200 ln/min 500 ln/min @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.003333 ln/s 0.03333 ln/s 0.3333 ln/s 3.333 ln/s 8.333 ln/s @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
12.88 ls/h 128.8 ls/h 1288 ls/h 12880 ls/h 32200 ls/h @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.2147 ls/min 2.147 ls/min 21.47 ls/min 214.7 ls/min 536.7 ls/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.003578 ls/s 0.03578 ls/s 0.3578 ls/s 3.578 ls/s 8.945 ls/s @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.01288 m3/h 0.1288 m3/h 1.288 m3/h 12.88 m3/h 32.2 m3/h @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.0002147 m3/min 0.002147 m3/min 0.02147 m3/min 0.2147 m3/min 0.5367 m3/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi
0.012 m3n/h 0.12 m3n/h 1.2 m3n/h 12 m3n/h 30 m3n/h @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.0002 m3n/min 0.002 m3n/min 0.02 m3n/min 0.2 m3n/min 0.5 m3n/min @ 0°C / 32°F and
1.013 bar / 1 atm / 14.69 psi
0.01288 m3s/h 0.1288 m3s/h 1.288 m3s/h 12.88 m3s/h 32.2 m3s/h @ 20°C / 68°F and
.013 bar / 1 atm / 14.69 psi
0.0002147 m3s/min 0.002147 m3s/min 0.02147 m3s/min 0.2147 m3s/min 0.5367 m3s/min @ 20°C / 68°F and
1.013 bar / 1 atm / 14.69 psi

What is the pressure drop over the instrument?

To determine the pressure drop over a MASS-VIEW instrument, you should visit our pressure drop section where we have published all information per gas per MASS-VIEW instrument at different flows and different inlet pressures.

What happens when I power up a MASS-VIEW flow meter for the first time?

This video shows what happens when a MASS-VIEW® mass flow meter is powered on the first time. (video length 43 seconds)

After MASS-VIEW is powered up:
        • first the pre-installed fluid can be chosen
        • then the corresponding range
        • the digital output /communication bus
          (analogue output (0-5V) is always on)
        • and at last, the security settings can be changed

Your instrument is ready for operation.

Which counter units are available to select?

The following counter units are available for MASS-VIEW®:

– when mass flow units are selected in the measure -> type menu: μg; mg; g and kg

– when volume flow units are selected in the measure -> type menu: ln; mm3n; mln; cm3n; μln; dm3n; m3n; μls; mm3s; mls; cm3s; ls; dm3s; m3s

Which flow units are available to select?

The following flow units can be selected on a MASS-VIEW®:

mass flow units: μg/h; μg/min; μg/sec; mg/h; mg/min; mg/s; g/h; g/min; g/s; kg/h; kg/min; kg/s

volume flow units (at normal conditions): μln/h; μln/min; μln/s; mln/h; mln/min; mln/s; ln/h; ln/min; ln/s; ccn/h; ccn/min; ccn/s; mm3n/h; mm3n/min; mm3n/s; cm3n/h; cm3n/min; cm3n/s; m3n/h; m3n/min; m3n/s; scfh; scfm; scfs; sccm; slm

volume flow units (at standard conditions): μls/h; μls/min; μls/s; mls/h; mls/min; mls/s; ls/h; ls/min; ls/s; ccs/h; ccs/min; ccs/s; mm3s/h; mm3s/min; mm3s/s; cm3s/h; cm3s/min; cm3s/s; m3s/h; m3s/min; m3s/s

Does the counter remember its value when the instrument is powered off?

Every few seconds, the MASS-VIEW® writes the countervalue to a non-volatile memory to be sure no data is lost after a powerfailure

From which measurement value does the counter start to count?

The counter function will start counting a measured value when the instrument measures a value of 2% or higher of its capacity. Below 2% nothing is counted.

The instrument is secured with a password but I don’t know the password. What can I do?

We have a (backdoor) solution for this, you can always use abc as password and then change the password again.

If you did not find your question, please search below.



McAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams
Authenticated and Verified by Verisign
Your transaction is 100% safe and secure  


Click for more information about our payment methods
We assume the above mentioned distributor covers your country. If you are from another country than as
displayed on the flag then click on the distributors in the main menu to see who does cover your territory.