Chemical Structure of the Liquid;
Wet parts of the flowmeter (those parts in contact with the liquid) should completely comply with the liquid for which it will be used.
This is possible only either by experience and knowledge of the fact that it has been used for the same liquid previously or confirmation of the suitability of the flowmeter from the chemical
compatibility schedules or confirmation by the manufacturing firm or approval by the customer.
Viscosity/Fluidity of the Liquid:
Viscosity limits of the flowmeters vary depending on the operating systems and their sizes, raw materials and trademarks. Temperature and viscosity are inversely proportional. For this reason, care
should be shown when selecting flowmeter for high viscosity liquids. For example, when a viscous liquid brought into the silo outdoor in the summer temperature passes through the flowmeter, same
liquid may not pass through the flowmeter when the air gets cooler.
Turbine type flowmeters may be used for the low viscosity liquids. Disc type flowmeters may be used for low and medium viscosity liquids. Oval-gear, track, ring, piston and helix rotor types of
flowmeters may be used for low, medium and high viscosity liquids.
Operating Pressure; Minimum Pressure: A minimum pressure is required for each flowmeter to operate. This quantity may be above the value of pressure loss. It is especially important on the lines
where when the flowmeters operate by the liquids own flow
Maximum Pressure: This is an upper limit specified according to the design of the flowmeter. Excess of this limit gives damages to the flowmeter. This value varies depending on the operating
principle, materials used and intended production purpose.
Operating and Ambient Temperature:
Ambient temperature: It means ambient temperature of the environment where the flowmeter operates. It is a value that should be paid attention especially in the hot environments such as boiler
rooms and in the very hot climates.
Operating Temperature: It is temperature of the liquid to pass through the flowmeter. It varies depending on the materials and types of indicators used on the flowmeter. Maximum and minimum limits
should be known.
Output Range (minimum and maximum flow rate):
Each flowmeter has a range of measuring. This value varies depending on the operating system and indicator type of the meter. The rate between the lower and upper limits is 1:10 or 1:20 in case of
turbine type flowmeters. It may be 1:100 in case of oval geared type flowmeters. However, this rate is not related with the measuring system completely. Type of indicator may also be determinant in
this respect.