Model 2000 Flow Computer Instruction Manual
2.0 GENERAL DESCRIPTION
Model 2000 issue 21 Page No
25
2.4.2. ULTRASONIC GAS METER
The Model 2000 Flow Computer can be connected to a Instromet Ultrasonic Gas Flow Meter type Check, Flare, P or Q Sonic
which has 1, 2, 3, 4 or 5 acoustic paths. The electrical connection is made using one of the communication port sockets set
up for the purpose. In a single stream version the communication protocol used is “Uniform” , where a packet of measured
data is sent by the meter every second to the M2000.The default communication details are as follows, these can be altered
if required:-
RS232
4800 baud
8 data bits
1 stop bit
No parity
In the case of multiple stream Instromet Ultrasonic meter inputs or Use with either the FlowSIC 600, the Panametrics GM868
or Daniel Senior sonic ultrasonic meters the Model 2000 uses a single Modbus RTU communication port configured for
multidrop use. When used with any of theses devices the relevant operating instruction manual for those devices should be
consulted. See paragraph 2.9 for details.
2.4.2.1. UNIFORM SOFTWARE
The Model 2000 Flow Computer can be provided with an additional communications port, which can be used to connect to a
PC computer (via RS232 connection) which is running the Ultrasonic Diagnostic Software ‘UNIFORM’. This communication
port provides the user with direct access to the ultrasonic meter through the Model 2000 without having to make or break any
field connections to the actual meter. The electrical connection is made using one of the communication port sockets set up
for the purpose. The communication details used must be set up to be the same as the communication port for the
Ultrasonic meter as listed in paragraph 2.4.2. All operating details of the UNIFORM software can be found in the relevant
Instruction Manual for the Meter and software.
2.4.2.2. METER CORRECTION FOR TEMPERATURE AND PRESSURE
A facility is provided which gives the option to correct the meter flow rate for effects of expansion due to Pressure and
Temperature. The options are selected using the parameter P/T Corr eqn. on the Ultrasonic set-up page and are:-
off No correction
Flange Correction for Flange Spool piece meters (See Equation).
Weld Correction for Welded Spool piece meters (See Equation).
For Flanged Spool piece meters
⎭
⎬
⎫
⎩
⎨
⎧
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−×
⎟
⎠
⎞
⎜
⎝
⎛
××
×
+−××α×+×=
−
)p(p
Ed4
D3
)t(t1031 Q Q
rara
6
c
For Welded Spool piece meters
⎭
⎬
⎫
⎩
⎨
⎧
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−×
⎟
⎠
⎞
⎜
⎝
⎛
××
×
+−××α×+×=
−
)p(p
Ed4
D7
)t(t1031 Q Q
rara
6
c
Where
Qc : Flow corrected for Pressure and Temperature
Q : Flow from Ultrasonic Meter
ta : Actual measured temperature in deg C
tr : Reference temperature in deg C
D : Spool piece inner Diameter in mm
d : Wall thickness in mm
E : Modulus of Elasticity in BAR
pa : Actual measured pressure in BARA
pr : Reference pressure in BARA
α : Thermal expansion coeff. in 106 C-1
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