KROHNE BM 70 A_P EN - Manual (Page 30)

Installation and operating instructions BM 70 A/P Page: 30 11/00
7.3 Replacement of the signal converter
Always disconnect from power source before commencing work!
Hazardous-duty systems
Before replacing the signal converter (instrument "head") in the hazardous location, make absolutely
certain that there is no explosion hazard (gas-free certificate). Allow the prescribed waiting time of 22
minutes to elapse before opening the housing!
1. Remove safety lock (see Sect. 9.3) with machinist's wrench, size 4 mm, and unscrew cover from
the terminal box with the special wrench. If a sunshade is fitted, remove this first (see Section
6.1.9).
2. Disconnect all cables from the terminals in the terminal compartment, see Section 7.8.
3. Remove the 4 Allen screws M (Allen key size 5 mm) and lift off the signal converter. The flange
unit (incl. waveguide window) will remain tight, also on pressurized tanks.
Caution
On pressurized tanks, do not on any account remove the 4 screws H connecting the waveguide
window to the BM 70 A/P flange! DANGER TO LIFE!
4. Install the new BM 70 A/P signal converter.
5. Check power voltage and fuse(s) (refer to instrument nameplate) and change or replace if neces-
sary, see Sect. 9.2 and 9.3.
6. Reconnect all cables in the terminal compartment as described in Sect. 7.8.
7. Check against the attached report on settings whether the factory-set parameters are correct for
your application. If not, reset the parameters as described in Sect. 8.
8. Subsequently, record the empty-tank spectrum, see Sect. 8.6.12.
Important:
Ensure that the screw thread of the covers on the terminal and electronic compartments is well
greased at all times.
7.4 Field assembly
•
When the BM 70 A/P needs to be field assembled, all
required parts are included with the supply (stud bolts,
washers, etc.).
•
If supplied loose, bolt the waveguide window (flange
assembly) or the distance piece to the BM 70 A/P.
Tightening torque for the 4 Allen screws M (key size SW 5
mm): max. 8 Nm ~ 0,8 kpm.
•
Note: The upper Teflon plug must be absolutely dry and
clean! Moisture and dirt will negatively affect functionability
of the BM 70 A/P!
•
Bolt antenna and antenna extension together: torque for the
3 stud bolts: max. 8 Nm ~ 0.8 kpm.
•
Do not on any account detach screws H!
distance piece (for
high-temperature version
up to 250°C (482 °F)
upper Teflon plug
O-ring
lower Teflon plug
O-ring
BM70 A
connecting flange
antenna extension
antenna
M
H
M
signal converter