5
3. Electronic Evaluation and Electrical Safety
Does the
supply voltage
of the flow meter match the available power supply?
Is the supply voltage to the power supply adapter or the evaluating device sufficiently
filtered
?
Does the
output
of the supply voltage correspond with the required output?
Is the electrical connection established based on the enclosed
wiring plan
(see page 19)?
Is the
cable shield
correctly grounded on both sides to a clean common ground (PE)?
Is there a
potential difference
between the ground on the flow meter and at the evaluating device?
Is the flow meter permanently
grounded (PE)
(e.g. via the pipelines)?
If the measuring element of the flow meter is
insulated
from ground (PE), the meter must be grounded with a cable!!
Is the
4-pin to 5-pin round pin plug
of the connection cable firmly attached to the plug of the flow meter?
Are the wires at the
evaluating
device connected correctly?
Does the entire system meet the legal rules and regulations concerning electromagnetic compatibility
(EMC)
?
Is compliance with all local rule and regulations,
applicable rules
, guidelines and basic conditions of the
EMC
ensured?
Systems where a malfunction or failure may lead to personal injuries must be equipped with
suitable safety mechanisms
. The function of these
safety mechanisms must be checked at regular intervals.
6. Maximum Operating Pressure
Before installing the flow meter, you must check whether the max. operating
pressure of the system does not exceed the max. permissible operating
pressure of 450 bar of the flow meter. Make sure to keep in mind that peak
pressures may occur when operating the system.
Important:
Please contact Omega with all operating pressures > 450 bar and in case of special models.
7. Information about the EU Pressure Equipment Directive 97/23/EC
Omega flow meters of the ”FHG“ series qualify as “pressure equipment“ as
defined by Section 1, Paragraph 2.1.4. of the directive listed above and as
such are affected by the regulations of this directive.
Omega flow meters must therefore meet the technical requirements speci-
fied in Section 3, Paragraph 1.4 of the directive. The fluids to be measured
are for the most part Group 2 fluids acc. to Section 9, Paragraph 2.2.
Omega flow meters do not reach the limit values specified by Section 3,
Paragraph 1.1. The technical requirements for Omega flow meters are
therefore confined to the criteria specified in Section 3, Paragraph 3. This
means that the devices must be designed and manufactured in accordance
with the provisions of good engineering practice applicable in a member
state. This is hereby confirmed. The section also stipulates that such pres-
sure equipment and components or accessories are not allowed to bear
the CE marking in accordance with the Pressure Equipment Directive. This
means that a declaration of conformity is not issued for Omega flow meters
and the devices are not provided with the CE mark as pertaining to Direc-
tive 97/23/EC.
Important:
Verify that the specified maximum permissible operating pressure of the flow meter
can never be exceeded in any operating mode of the system. Also pay attention to the
flow measuring range, which is dependent on the viscosity of the fluid to be measured.
8. Flow Rate Measuring Range
The
flow rate
measuring range specified in the data sheet (Q
min
– Q
max
)
of the flow meter refers to the test fluid ‚hydraulic oil‘ with a viscosity of
21 mm
2
/s at a temperature of 20°C. For this measuring range, Omega
specifies accuracy up to 0.3% of the measured value and a repeatability
of 0.05%.
In fluids with low viscosity (< 21 mm²/s), the measurement accuracy de-
grades while it may improve with fluid with a high viscosity (> 21 mm²/s).
Note also that the flow measuring range is limited at higher viscosity (see
data sheet of the flow meter). The characteristic pressure loss curves are
listed in Section 23.
