OPERATING MANUAL HPC & UMC4
Page 19 of 105
Type of fluid
Position
Assessment
Position D
No gas bubble accumulation in the tubes, liquid residues
may however remain in the sensor after discharge
Liquids containing
substances that could
form deposits
Standard Position A
Self-draining flow tubes, no deposit formation
Position B
OK
Position C
Substances in the liquid could form deposits at low flow
velocities
Position D
Not recommended owing to the presence of substances
that could form deposits in the tubes
Liquids containing
gas bubbles, as well
as substances that
could form deposits
Standard Position A
Self-draining flow tubes, no accumulation of gases or
forming of substance deposits in the tubes
Position B
Not recommended owing to gas bubble accumulation in
the tubes
Position C
Gas bubbles or substances could form deposits at low
flow velocities
Position D
Not recommended, substances could form deposits in
the tubes
Gases that do not
form a condensate
Position A, B, C or D
Any of the installation positions may be used
Gas, condensate-
forming gas/liquid,
moisture
Standard Position A
Flow direction should be from top to bottom to ensure
forming condensate can flow out efficiently
Position B
OK
Position C
Condensate might form in the tubes
Position D
Not recommended owing to condensate accumulation in
the tubes
Slurries
Standard Position A
Optimal installation position
Position B
High density substances could accumulate in the tubes
Position C
Gas bubbles could accumulate
Position D
Gas bubbles or high density substances could accumu-
late in the tubes
4.4.3 Pressure surges
Pressure surges in a pipe could be provoked by a sudden decrease in flow caused by rapid closing of
a valve or similar factors. This change in pressure can lead to negative pressure downstream from a
valve that has been closed rapidly, and to outgassing. If the valve is mounted directly on the inlet sec-
tion of the flow meter, a gas bubble can form in the flow tube that can cause a measuring signal dis-
turbance which would shift the zero point of the output signal. In extreme cases, a pressure surge
could cause mechanical damage to the sensors and/or flow tubes.
Whenever possible, quick-closing valves should be mounted downstream from the sensor. If this is not
feasible, such valves are to be mounted a minimum of 10 x DIA (
Φ) from the nearest sensor. Alterna-
tively, valve closing speed can be reduced.
