Kobold DF-**01 series, User Instructions

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11 DF-SEN
FM Rev. 12/13
• During operation, there are a number of situations to avoid:
a. The sudden cessation of fluid flow causes what is typically referred to as
"water hammer". Most people are familiar with this phenomenon from their
home experience - it is the cause behind the loud clank of water pipes which
occurs when faucets are turned off too suddenly. The cause behind this
"water hammer" is quite easy to visualize. Water is fairly massive. The
amount of water in long runs of pipe is quite substantial. When the faucets are
turned off suddenly, especially from a full on condition, the water has
considerable momentum and does not want to stop flowing. The situation is
similar to stopping a car by running into a wall, rather than by applying brakes.
Both are sudden rather than gradual. The damage to the wall can be
substantial (not to mention the car).
The "water hammer" causes surges in fluid pressure which could cause the
measurement instrument's pressure limit to be exceeded, resulting in failure
and possible personal injury.
b. Fluid surges, as well as the water hammer, can be particularly damaging to
empty flowmeters since there is no back pressure in the device. The damage
is caused, once again, by momentary excess pressure. To avoid these
surges, fluid lines should remain full (if possible) and water flow should be
introduced to the device slowly.
c. If the instrument is isolated with inlet and outlet valves, the instrument must be
completely drained when said valves are both closed. Failure to do so could
result in damage to the device caused by thermal expansion of fluid.
d. Freezing of water in the instrument MUST be avoided since the resultant
expansion will damage the instrument and make it unsafe for use.