Accuracy
The accuracy desribes a tolerance range of measured values. Meister Strömungstechnik declares the accurary.
- in % of full scale
- in % of measuring value
- Accuracy class according to VDI/VDE 3513
Adjustment
The adjustment describes the procedure of adjusting the customer specified switch point.
Ambient temperature
Temperature range in the ambience of the measuring instrument.
Approval
Many instruments of Meister Strömungstechnik can be delivered with UL and/or ATEX certification. They have been checked on different aspects relevant for safety.
ATEX
ATEX (ATmosphères EXplosibles) requires the employer and/or user to prevent explosions and ensure protection.
With regard to explosion protection in a potentially explosive environment, ATEX Directive 2014/34/EC and ATEX Directive 1999/92/EC take precedence over Machinery Directives and must be applied.
Celsius
Swedish physicist, who defined a temperature scale in 1742. The corresponding unit is [°C]. The Celsius scale is defined by the freezing point (0°C) and the boiling point (100°C) of water.
Connecting size
Measuring unit depends on connection type:
Threaded connection: [in] (inch)
Flange connection, sandwich mounting, clamp connection, glue connection: [DN] (nominal size)
Hose connection: [mm] (millimeter).
Connection
Required process connection of the measuring instrument (threaded connection, flange connection, sandwich mounting, hose connection, clamp connection, glue connection)
CSA, Canadian Standards Association
The Canadian Standards Association is an organization that tests and certifies products for security relevant issues.
Display
Several principles to visualize the volume flow.
Fahrenheit
German physicist, who definied a temperature scale. The temperature is measured in [°F]. Not with standing the orginally defined fixed-points, the Fahrenheit scale was defined by the freezing point and the boiling point of water in a redefinition in which the freezing point liest at 32°F, like Fahrenheit specified it.
Hysteresis
Hysteresis describes the difference between switch-on-point and switch-off-point of a flow monitor. The flow monitor toggles when an adjusted limit flow is reached. This switching status is kept until the hysteresis gets exceeded.
Kelvin
British physicist who defined a temperature scale. The zero point of the scale is the physically absolute and really not reachable zero point where the particles do not have any more kinematic energy. This point lies at -273,15 °C. The measuring unit is [K]. Intervals on the Kelvin scale are identic to the Celsius scale. [K] is the SI unit for temperatures since 1968.
Magnetic-inductive measuring principle
Two magnetic coils build up a magnetic field that is flown through a conductive medium. Dependent on the speed of the flow, a measurable voltage is induced. Consequently, the flow speed can be deduced from the amount of the voltage and can be converted into a volume flow with the area cross-section.
Mass flow
The mass flow describes what mass of fluid flows through the cross-section of a pipe within a defined time (unit i.e.: [kg/h]).
Medium
The fluid to measure, e.g. water, oil, air.
Medium temperature
Temperature of the medium
Nominal flow
User-specified flow at trouble-free operation.
Nominal size
The nominal size describes the connection size of measuring instruments. The nominal size for tubes is mostly specified in [inch], flange connections in [DN] (Diameter Nominal).
Operating density
Relation of mass to volume of the fluid to measure under operating conditions.
Operating pressure
Static pressure in the system at the position of the measuring instrument (units: [bar], [Pa], [psi]).
Operating temperature
The temperature of the fluid to measure under operating conditions.
Operating viscosity
The viscosity is differed in kinematic viscosity (unit: [cSt]) and dynamic viscosity (unit: [cP]). The higher the viscosity, the viscid the medium.
Pressure, absolute
The absolute pressure is 0 bar in the absolute vacuum.
Pressure, maximum
Maximum allowed operating pressure in the application. It is generally stated as relative pressure.
Pressure, relative
Static pressure related to the ambient pressure (relative pressure + atmospheric pressure = absolute pressure)
Process connection
see Connection
Reed relay
A reed relay is a relay made of a glass tube with fused-in pair of contacts on ferrous metal. Dependent on the relay type, bringing a magnet near to the relay makes the contacts close (normally open), open (normally closed) or change (change over).
Sealing material
A wide variety of materials are used to make seals. They are chosen depending on the medium to be measured and the operating conditions.
Sensor element
The sensor element defines, which measuring principle is used (e.g. float, impeller).
SI unit
A SI unit is a unit belonging to the SI system of units (Système International d'unités). It was introduced in 1960 and has become the standard system for phyiscal units today.
Signal output
Desired electrical output signal of the instrument (voltage 0 - 10V, current 4 - 20 mA, impulse).
Switch contact
Contact for electrical monitoring of flow rate limits. Normally open and change over versions.
T-piece
A T-piece is a link for pipe and hose connections that allows flow branching.
UL-certification
The Underwriters Laboratories are an organization in the USA that check products concerning their operating safety. UL-certifications are issued product related and are often required for a market access in the USA.
Ultrasonic flowmeters
The ultrasonic flow measurement is based on transmission and reception of sound waves with ultrasonic frequency. The flow speed can be deduced from different effects that the sound wave has on the fluid. Several methods are used for this, like a transit time measuremt or the Doppler method with wich a frequency offset of the original sound wave can be analyzed. The selection of the method is dependent on the medium.
Volume flow
The volume flow describes, what volume of a fluid flows through a cross-section of a pipe within a defined time (units i.e.: [l/min], [l/h], [m³/h])
Water, demineralised
Demineralised water is chemically clear H2O that, in contrast to distilled water, is much more contaminated. Because it is more simple and cheaper to make demineralised water, it is used much more often.
Water, distilled
Distilled water is chemically clear H2O that doesn't contain any minerals or micro elements. It contains ions in a minor degree because of Autoprotolyse what makes distilled water conductive. Distilled water is made by evaporating and condensation of water (distillation).

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