Lutz 0212-100, Руководство по эксплуатации

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1.4 Complete hose system
Before initial starting of the flow meter, the entire piping system must be vented from the pump through to the
shutoff element (nozzle, solenoid valve or similar). During operation, care must be taken to ensure that the
complete system is filled with liquid.
1.5 Pressure surges (water hammer)
Considerable pressure fluctuations with so-called water hammer can build up in the system as a result of delays
(disconnection/shutoff) or acceleration of the flowing liquid column when using long delivery lines or when using
solenoid valves with short opening and closing times.
Warning!
The brief pressure peaks or surges due to water hammer can cause serious damage and destroy the
flow meter, pump or other components in the system!
Damage by uncontrolled splashing liquid. Depending on the medium concerned, this can lead to
caustic burns, explosion hazards, toxic vapours, electric shocks, danger of slipping and other dangers!
Example: A valve closing time of 20 ms can cause a pressure surge of up to 10 bar in a 10 metres long 1" pipe
at a flow rate of 50 l/min.
Pressure surges can be prevented as follows:
• Use a larger nominal diameter (DN) to reduce the flow speed in the delivery line.
• Filling with step-by-step interruption (SLOW mode, see chapter C 3.2.9).
• Use relief valves and pressure limiting valves to eliminate impermissible pressure peaks.
1.6 Pressure drop
Diagram 2 indicates the pressure drop relative to flow. The solid line is applicable for aqueous liquids
(
r »
1 kg/dm³,
h »
1 mPas).
In case of media with different density (
r ¹
1 kg/dm³) the pressure drop values have to be taken from the solid
line in diagram 2 and multiplied by the density value of the liquid.
Media with a high dynamic viscosity (
h >>
1 mPas) like high-density media, cause a higher pressure drop. The
limiting curve for permissible viscosity at
r
= 1 kg/dm³ is depicted in diagram 2 as a dotted line. If the density
r
is greater than 1 kg/dm³, the pressure drops in the diagram must be multiplied by the actual density.
B. Basic flow meter
Diagram 2
Pressure drop depending on flow rate.