Operating Instructions KDF-9/KDG-9
Page 5
KDF-9/KDG-9 K04/0922
1 Applications
1.1 KDF-9 / KDG-9
The flow meter can be used for measuring the flow of liquid and gaseous products in pipes.
It shows the current flow in volume or mass per unit time.
Applications:
Measuring the flow of liquid and gaseous products in pipes as well as dosing, superimposing, monitoring,
regulating and controlling them.
1.2 KDF-9 / KDG-9 differential pressure regulator
The flow meter can be used for stabilizing a constant flow of liquid and gaseous products in pipes. The
flow is kept constant regardless of pressure changes during product inflow for type KDF-9 / KDG-9-...E/F
or of a pressure change during product outflow for type KDF-9 / KDG-9-...A/B.
Applications: Constant dosing, level measurement in open and closed vessels, N
2
superposition of
combustible media
Caution:
The devices should be used with the greatest possible caution to measure potentially hazard-
ous liquids and (especially) gases. Precautionary measures must be taken to protect personnel and
equipment from any potential danger or damage due to glass-tube breakage. The plant operator is fully
responsible for using the devices. Where possible, we recommend the use of metal devices such as type
KDS.
2 Operational mode and system design KDF-9/KDG-9
Float principle:
The product flows through the meter vertically from the bottom to the top. The height of the float in the
measuring tube is a measure of the flow quantity. The float is in equilibrium between the buoyant force of
the flowing medium and the counteracting force of gravity on the float. The measured value is displayed
on the measuring-tube scale with the upper edge or the indicator edge of the float (ball).
2.1 KDF-9 / KDG-9 system design
The meter consists of a conical measuring tube made of glass containing a float that can move vertically.
The height of the float in the measuring tube reproduces the calibrated flow quantities on the measuring
tube.
2.2 Measuring principle for KDF-9 / KDG-9
Differential pressure regulator
The diaphragm of the controller is in a state of equilibrium when the pressure conditions are the same on
both sides. The pressure on the input side is determined by the pressure of the product; the pressure on
the output side is determined by the pressure drop of the setting valve of the flow meter.
If either the inlet or outlet pressure changes, the change in pressure is compensated by the built-in dia-
phragm valve - thus maintaining a constant set flow rate.
Important:
The controller can only regulate inlet or outlet pressure fluctuations. Steady pressure condi-
tions must prevail on the other side.
2.3 KDF-9 / KDG-9 system design
The unit consists of a KDF-9/KDG-9 variable-area flow meter, equipped with a diaphragm differential
pressure flow controller. The variable-area flow meter consists of a device fitting with an integrated meas-
uring tube made of glass that contains a vertically movable float and the valve for setting the flow rate.
The differential pressure flow controller is made of stainless steel and consists of a diaphragm made of
Viton or PTFE and a compensating valve made of stainless steel. For gaseous products, two versions are
available:
KDF-9/KDG-9-...A/B
for a constant inlet pressure and a variable outlet pressure
KDF-9/KDG-9-...E/F
for a constant outlet pressure and a variable inlet pressure
For liquids, both versions can be used; however, the
KDF-9/KDG-9-…A/B
version should be preferred.