Barksdale BNA 21 Operating Instructions Manual page 5

NOTE
Ensure that the flanges of the tank are accurately aligned with the flanges of the BNA.
Non-alignment of the flanges causes seizing or distortion of the BNA (1/4). The float (1/5) may
get jammed.
The principle of operation of the Bypass Level Indicator is based on the magnetic field principle.
No magnetic iron parts (e. g. screws, clamps etc.) must be used in the vicinity of the level tube.
Observe the data in chapter 8 „Technical Data".
 Install the BNA so that the nameplate (1/11) of the BNA (1/4) is located at the bottom.
 Align all indication rotors (2/12) by means of a magnet or the enclosed float. All rotors must
show the colour white or silver;
white: makrolon, medium temperature up to 150 °C or aluminium, medium temperature up to 350 °C
silver: aluminium, medium temperature up to 200 °C
The maximum ambient temperature is 120 °C.
 Ensure that all flange attachment screws, the vent plug (1/13) and the drain screw (1/14) are
tightened or closed properly.
Torques for the screws:
Type Screw dimension
X1 M12
Plug G½, ½" NPT
Fastening clamp 7 mm hexagon head
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Torque [Nm]
50
80
0.75
Electrical installation
DANGER
The orderer must ensure that all applicable regulations are observed in the event that electric
limit switches and remote indicators are used.
For further information about installation of the electric limit switches and remote indicators refer to
the corresponding installation and operating instructions.
Commissioning
The Bypass Level Indicators (BNA) are specially made for a specific application. The most
important data, such as flange, pressure, temperature and min. specific gravity of the float are
specified on the nameplate (1/11).
 Check prior to commissioning whether the technical data according to the nameplate are in
agreement with the plant requirements.
Operating pressure and operating temperature of the plant must not exceed the data stated on the
nameplate of the Bypass Level Indicator. Exceeding the limit values will cause changes in the
behaviour and service life of the BNA. If the proof pressure is exceeded, functioning of the BNA is
no longer guaranteed and the BNA may be damaged.
 Ensure that - dependent on the type of medium to be measured - the appropriate safety
precautions are taken.
Filling the Bypass Level Indicator
 Slowly open the top valve (1/2a).
 Slowly open the bottom valve (1/3b).
The liquid rises slowly in the BNA (1/4). The float (1/5) is lifted until the same level is reached in the
tank (1/1) and in the BNA.
 Fully open the bottom valve (1/3b).
NOTE
For pressures above 40 bar a vented float (additional designation: -VAE) is used which is
provided with a small pressure compensation tube.
When using the VAE version take care that the temperature in the BNA and in the float rises
evenly and slowly. The use of vented floats should be discussed with the manufacturer
beforehand.
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