Yokogawa RotaMASS 3-Series - Manual (Page 189)

8. SElF-dIAgNOSTIC ANd TrOUBlESHOOTINg
8-13
IM 01R04B04-00E-E 8th edition March 01, 2011 -00 All Rights Reserved. Copyright © 2003, Rota Yokogawa
The ROTAMASS RCCx34 ... 39/XR was tested and FM- approved according to ANSI/ISA – 12.27.01 – 2003
for Canadian Dual Seal Approval. For units with option /DS this is stated on the name plate.
NOTE
If ROTAMASS flowmeter is not used in Canada this functionality can also be used without Dual Seal approval.
The primary seal (metering tube) and the secondary seal withstand the maximum test pressures forced for
the maximum flange pressure of 12.41 MPas / 1800 psi (Flange A4, ASME 900). However the enclosure do
not withstand this pressure. For details see GS 01R04B04-00E-E.
When the metering tube fails, the detector enclosure is filled with process medium and the density reading
of ROTAMASS increases rapidly. This can be used for detecting a primary seal failure by the following an-
nunciation methods:
A) via too high density reading, preferable with liquid application
- Set “Basic setup / Density / Density URV about 0.3 kg/l above the highest possible process density.
- Set an output (current or frequency) to density transmission.
- If the URV is reached (e.g. 20 mA ) the primary seal failed.
- Set
Status output to density alm 1 and status output will be active in case of tube failure.
B) via Status output and “Empty pipe detection”
Only for liquid (only possible with software version 1.7 or higher):
- Check parameter "Basic Setup / Density / Density URV" (Default value is 1.5 kg/l).
URV should be about 0.3 kg/l higher than any density the process can provide.
- Set parameter "Detailed Setup / Empty pipe detect / Empty pipe alm sel / Apply".
- Set parameter "Detailed Setup / Empty pipe detect / Empty pipe crit / ..." to a value
which is a little bit higher than Density URV.
- For detection with e.g. status output 1:
Set "Detailed Setup / Config Output/Input / Pulse/Status out 1 / Pulse/Stat 1 select / Status out".
Set "Detailed Setup / Config Output/Input / Pulse/Status out 1 / SO1 function / Empty alarm"
- When the metering tube fails, the detector housing is filled with the process medium and the density
increases. Alarm A15 "Empty pipe detection" appears, display is blinking and the status output is set
active.
C) via rupture disk (option /rd), preferable with gas application
- When the metering tube fails, the installed rupture disk bursts at about 20 bar (290 psi).
- For gas application the result will be a whistle by the gas blowing out.
- Rupture disk is only for annunciation.
WARNING
If rupture disk bursts, the hazardous process medium is pressed out of the detector housing to the
environment. Take care that no worker gets contact to the medium.
8.8 detection of metering tube failure