The innovative MASS-VIEW flow meter is a digital alternative to the conventional rotameters, also known as variable area (VA) meters or purge meters. The MASS-VIEW Series, from Bronkhorst, incorporates a digital bar graph of actual gas flow, which uses OLED (organic light emitting diode) technology for clear visibility from all angles. It displays flow units, gas type, and totalized figures. MASS-VIEW flow meters, regulators, and controllers are equipped with a built-in needle valve for manual control of the gas flow. As an extra feature, the flow controller is equipped with a pressure compensation membrane, which eliminates the effects of upstream pressure variations.
The MASS-VIEW Series is designed to mimic the straightforward features and vertical format of rotameters, but with the added benefits of an electronic output signal, high measuring accuracy, virtual independence from gas temperature and pressure variations, freedom from parallax error, and inherently safe construction, by eliminating fragile glass components in the flow path.
The MASS-VIEW Series are accurate flow instruments for measuring and controlling the mass flow rate of gases. They are an innovative series of mass flow meters, regulators, and controllers with integrated display. MASS-VIEW, from Bronkhorst, provides a modern, novel, and economical alternative to rotameters, also known as variable area meters (VA meters) or purge meters. Unlike conventional rotameters, these flow meters measure the flow of mass instead of volume. For easy rotameter replacement, MASS-VIEW’s mechanical construction offers most of the common options for process connections.
The MASS-VIEW Series operates on the principle of direct thermal mass flow measurement (no bypass). An advantage of using this type of sensor is that these flow instruments measure direct mass flow, virtually independent of pressure and temperature changes, and have a low pressure drop. Other advantages compared to conventional rotameters are the high accuracy and the large rangeability.
The MASS-VIEW Series feature totalizer and alarm functions. Flow control can be achieved by an optional built-in needle valve. MASS-VIEW flow meters can be supplied in full scale ranges from 0.05 up to 500 ln/min (air equivalent), with a pressure rating of 10 bar(g) or 150 psi(g). A bright graphical OLED display, clearly visible at wide angles, allows reading of actual flow (value and a bar graph), total flow, and gas type. The display features easy navigation through a user-friendly menu, using a 4-way button with center push. Furthermore, this low flow gas mass flow instrumentation has 2 potential free alarm contacts grounded on one side.
An advantage of using this type of sensor is that the instrument measures direct mass flow, without the need of temperature and pressure correction. Other benefits, compared to conventional rotameters, are higher accuracy, wider rangeability (up to 1:100), free of parallax errors, and an inherently safer construction, by eliminating glass components in the flow path.
lowest range: 0-0.2 ln/min
highest range: 0-500 ln/min
lowest range: 0-0.2 ln/min
highest range: 0-50 ln/min
* ln/min equals SLM at 32˚F (0°C) and 1 atm (STP)
The display features easy set-up via a user-friendly menu using a 4-way navigation push button. Gas settings are preinstalled to eliminate the need to recalibrate for different gases, thereby reducing time and labor costs. Additional features and functions include a variety of alarm and counter functions, an analog output signal, digital interfaces, and two relay contacts.
Flow control may be achieved with an optional needle valve. These high quality needle valves offer smooth and fine adjustment of the gas flow rates. The latest innovation to the MASS-VIEW product line is the addition of an integrated auto-compensating controller. The desired flow rate is set via the needle valve in the usual way, however, any upstream pressure variation is now automatically compensated to ensure a steady, constant flow.
The 4-way navigation push button provides access to a user-friendly menu, e.g. for zero function, selection of preinstalled gases in preinstalled capacities, setting of engineering units, alarm functions (minimum / maximum / counter limit), and counter functions. Also, password protection is provided to prevent unauthorized changes. These smart instruments offer multiple process values as input or output parameters. Many parameters can be changed on the instrument through the menu, other parameters can only be changed using digital interfaces.
The needle valve has an orifice with a long, tapered conical seat. A needle-shaped plunger, on the end of a screw, exactly fits this seat. As the screw is turned and the plunger retracted, so flow between the seat and the plunger increases. Since it takes many turns of the fine-threaded screw to retract the plunger, precise regulation of the flow rate is possible.
Flow control with a needle valve at constant pressure results in a constant flow rate. But when pressure conditions change, the flow will also change. With a constant-flow controller with varying upstream pressure the flow will almost be constant. By keeping the pressure drop across a needle valve constant the flow rate also is constant. Deviations of the pressure drop are compensated by a membrane operated valve. This membrane is actuated by a spring. The spring force closes the valve. The equilibrium between closing (valve spring) and opening (membrane) keeps the flow constant.
The spring force in the upstream membrane valve closes the valve in the “zero” flow situation. By opening the needle valve the ΔP will increase, so far that the membrane lifts up and compensates the spring force. In the equilibrium position the flow will be constant even when the upstream pressure (Pin) changes. However, when the upstream pressure increases, it will cause a small effect on the spring force, which means that the ΔP to open the membrane valve will be a little smaller. And this results in a lower flow.
The MASS-VIEW Series operates on the principle of direct thermal mass flow measurement. The thru-flow design sensor consists of a heater resistor and a temperature sensing resistor. 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).
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