CXX-UM-01850-EN-01
Turbine Input
Three voltage pulse inputs are provided for connection to three turbine pre-amplifiers The flow computer does the following:
1 Measures the frequency of each turbine input
2 Divides each frequency by the viscosity to obtain the uncorrected Hz/Viscosity
3 Multiplies the derived value by the Roshkoe number to obtain the corrected Hz/Viscosity
4 Uses that value to obtain an uncorrected turbine K-factor using the 30 point frequency/viscosity versus K-factor curve
5 Multiplies the derived value by the Strouhal number to obtain the corrected K-factor
6 Divides the measured frequency by the corrected K-factor to obtain the flow rate in volume per second, which may then
be multiplied by the desired time base (for example, 60 for volume per minute)
7 Converts the volume flow rate to the mass flow rate using the 30 point temperature versus S G curve
8 Totalizes the mass flow rate
OTEE:
N
You can prevent totalization by shorting together terminals 34 and 36 at the rear terminal block
Auto-ranging Mode
The computer operates in either auto-ranging mode (MANIFOLD ON), or in non-auto-ranging mode (MANIFOLD OFF)
In auto-ranging mode, three valve control relays are used to select the correct channel in accordance with
the programmed frequency setpoints This procedure is described in detail in the auto-ranging section
"Setup Auto/Manifold Auto-ranging Trip Points" on page 20
As the computer changes the relay contacts, it automatically displays the status of the channel to which it has switched
For example, while running on channel 1 the flow is increased to switch to turbine 2 The menu then changes to rt
2
or mas
2
according to the option selected at that time In auto-ranging mode, the flow rate of all turbines is totalized on tot
1
In
non-auto-ranging mode, the flow rate is referred to the identifier applicable to the channel in operation
Special Instructions
Page 28
February 2018
