Yokogawa RotaMASS 3-Series - Manual (Page 227)

11. TECHNICAl dATA
11-5
IM 01R04B04-00E-E 8th edition March 01, 2011 -00 All Rights Reserved. Copyright © 2003, Rota Yokogawa
Heat Tracing and Insulation
Basically the detector can be insulated by the customer.
To be sure not to overheat the connection box choose one
of /Tx options (insulation or heat tracing from Yokogawa). For
temperatures between 150°C and 230°C choose /MT option
and remote installation. For low temperature fluids ask for
special insulation. If Rotamass detector with /MT or /HT is not
insulated, the accuracy specification can not be guaranteed.
The converter should not be exceeded more than 50°C.
Therefore never insulate the converter and keep the neck
free from insulation too. Yokogawa will not take any liability
regarding customer insulation.
relations between Options /MT, /HT, /S2 and /Tx ( /T1,
/T2, /T3)
The meters with high temperature options (/MT, /HT) can
be insulated either by the customer by using option /S2
(prolonged neck) or by the factory through options /Tx.
The /Tx options already include the option /S2 so that the
/S2 option can not be selected in case of the /Tx options.
If the meter is not properly insulated by the customer, the
accuracy specification can not be guaranteed.
Installation above 100°C process Temperature
To provide enough cooling the instrument should be installed
vertically or horizontally with the converter down. This is rec-
ommended for size RCCT/S36 and larger without /Tx option.
Installation below 0°C process Temperature
The detector can be insulated to prevent ice capping either
by the customer or by the manufacturer. Ask your Yokogawa
representative for special insulation. If the customer wants
to insulate by themselves a closed cell foam as insulation
material is recommended to avoid water siphon. In this case
option /S2 should be selected. For temperatures below -70°C
option /LT is recommended (on request).
Zero Adjustment Function
Zero point can be adjusted either by setting the switches on
display or with the HART communication or with status input
when the fluid flow is stopped and the detector filled.
To ensure no flow conditions isolation valves should be
installed. To achieve the specified accuracy a zero should
be performed at process conditions (temp., pressure).
pressure / Temperature dependencies of process Connections
See also process pressure limits in chapter ”Normal operation
conditions”.
rupture disk
The rupture disk is used as annunciation method in the case
of tube rupture (Dual Seal) preferable for high pressure
gas service. Practically a tube rupture of ROTAMASS is
not known to the manufacturer. For large sizes it cannot be
expected that the full line pressure can be released via the
rupture disk. If this is requested please contact Yokogawa
for a special execution.
plANNINg ANd INSTAllATION HINTS
design limits
It is the responsibility of the user to use the instrument within
the given design limits. Erosion and corrosion influence the
accuracy and may restrict the temperature / pressure limits.
Therefore corrosion and erosion should be avoided.
Installation
The flowmeter can be installed vertically, horizontally or
in any other position, as long as the measuring tubes are
completely filled with the measured liquid during measurement.
redundant Installation
If two flowmeters of the same size are installed in series
mutual interference called cross talk may take place. Cross
talk occurs due to the fact that both meters have the same
resonance frequency. If serial installation is planned please
contact your Yokogawa representative who can ensure that
a frequency adjustment is made to one of the meters at the
factory.
Sizing
The measuring range and accuracy are virtually independent
of fluid conditions and size of the connecting pipe. Select a
suitable nominal size from pressure loss calculation. Check
whether the measuring range and accuracy at minimal flow
fit the application. The calculations of the pressure loss are
based on Newtonian fluids. For correct calculation of the
pressure drop use the YOKOGAWA Sizing software.
Sanitary Applications
For sanitary applications select process connection S2, S4 or
S8. The wetted surface will be Ra ≤ 1.6 µm. However, if
option /SFx is selected the surface roughness will be
Ra < 0.8µm and with /SF2 a certificate with a 3- point
roughness measurement certificate is delivered. The EHEDG
certificate shows that ROTAMASS conforms to the EHEDG
criteria regarding the capability to be cleaned by a CIP
process. The evaluation does not include the process
connections and seals.
Cavitation
To avoid cavitation keep the back pressure of the fluid suffi-
ciently above the vapor pressure of the fluid. For low viscous
fluids following condition should be fulfilled at the given
temperature:
p
back
> p
vapor
+ 0.7*∆p
With ∆p = pressure loss (e.g. given by the Yokogawa sizing
software)
long Term Stability
To get stable deflection of the tubes by the coriolis forces the
stiffness and therefore the wall thickness has to kept constant
during measuring. With corrosion or erosion the meter factor
is drifting with time and recalibration is necessary. Select the
suitable resistant tube material for the process!
recalibration Service
Yokogawa offers via its European Flow Centre (Rota Yokogawa,
Germany) full recalibration service, if necessary with a
certificate traceable to German national standards. Please
contact your Yokogawa affiliate or directly Rota Yokogawa,
Germany.