RMG TERZ 94, Руководство по эксплуатации

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Installation
Operating Instructions for the TERZ 94 Electronic Turbine Meter
11
Pressure loss
The pressure loss is calculated using the following formula:
4
2
M
P
DN
Q
Z = p
⋅ ρ ⋅ Δ
where
Δ
p is the pressure loss [mbar]
Z
P
is the pressure loss coefficient
ρ
is the density [kg/m
3
]
Q
M
is the flow rate at measurement conditions [m
3
/h]
DN is the nominal diameter of the meter [mm]
The pressure loss coefficient Z
P
is constant for all volumeters of the types
TERZ 94 and TERZ 94-S. It is:
Z
P
= 5040
This is an approximate mean value. The exact value is calculated from the
pressure loss which is determined on testing the volumeter.
Example of calculation:
Q
M
= 650 m
3
/h; DN 150;
ρ
= 1.3 kg/m
3
[natural gas, 600 mbar]
mbar 5 . 5
150
650
3 . 1 5040
DN
Q
Z = p
4
2
M
P
4
2
= ⋅ ⋅ = ⋅ ρ ⋅ Δ
Therefore, the pressure loss
Δ
p with a volumeter of the type TERZ 94 is
5.5 mbar in this case.
Installation
The gas flow must be free of shocks and pulsations as well as free of foreign
particles, dust and liquids. Any components affecting the gas flow must
absolutely be avoided directly upstream of the TERZ 94 volumeter.
To achieve the highest possible accuracy (measuring error <1%), an inlet
pipe of 2 DN in length with a perforated-plate straightener should be installed
upstream of the meter.