01
Gas dosing is not precise enough
02
Process changes go unnoticed
03
Reactors behave differently
04
Ambient conditions affect gas flow
05
The control loop is not properly tuned
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PROBLEM MAP
Why your bioprocesses never quite stabilise
Vögtlin uses drift-free MEMS sensors and precise temperature compensation to ensure that a setpoint consistently produces the same physical gas flow.
Vögtlin displays the actual gas flow in a way that is both visually apparent and digitally accessible, allowing the setpoint, actual value, and system behavior to be checked at any time.
Vögtlin combines reliable hardware with fast technical support, calibration services, and long-term support.
Thermal mass flow meters and controllers directly measure the number of gas molecules (mass) flowing past the sensor.
This measurement principle allows for large fluctuations in temperature and pressure without significantly affecting the measurement result.
A sophisticated temperature compensation system results in barely measurable differences in the range from 0 to 50°C.
Gases can be compressed. Their volume changes when the temperature and/or pressure change.
Consequently, when specifying a gas volume, the reference temperature and reference pressure must always be specified as well.
Our specifications are based on the requirements of DIN 1343 (standard conditions):
Temperature Tn = 273.15 K, corresponding to 0°C
Pressure Pn = 1013.25 mbar abs
See also: http://de.wikipedia.org/wiki/Normbedingungen
Not everyone understands “standard conditions” in the same way. While there is general agreement on the reference pressure, there are differences regarding the reference temperature:
The U.S. standard liter corresponds to our standard liter according to DIN 1343.
Gas suppliers in Europe specify 15°C rather than 0°C.
To avoid misunderstandings, the reference conditions are clearly stated in our correspondence.
Upon request, we can also supply the devices with a different reference temperature (e.g., based on room temperature of 20°C).
The reference pressure is set to 1013.25 mbar for all units. If, for example, you want to calculate the difference between 0°C and 20°C, the formula is as follows:
(Flow rate at 0°C / 273.15) * 293.15
Example: 100 ln / 273.15 * 293.15 = 107.32 ls
This corresponds to a correction of 0.366% per degree Celsius
We recommend the following calibration interval:
1. Initial inspection after one year
2. After several consecutive calibrations have been performed, the variation from one calibration to the next must be evaluated. Based on this data, a decision can be made to adjust the calibration intervals.
Yes. In many cases, it’s much easier for our service team and for our customers if we can access the customer’s computer directly.
Often, it’s just minor issues that cause devices to malfunction. Please contact us.
Moist gas up to approximately 97% rH has only a minor effect on measurement accuracy. However, appropriate measures must be taken to ensure that no condensate forms inside the measuring instrument.
Condensate accumulates on the sensor and leads to measurement errors. If a measuring instrument has come into contact with condensate, it can usually be purged with a dry gas such as N2. See also the instructions in the user manual.
