Lutz B70V, Translation Of The Original Instructions

Page: 22 / 28

22
GB
8. Explosion proof pump tubes
8.1 General
The eccentric screw drum pumps type B70V are used to pump
from mobile vessels flammable liquids, which belong to the
explosion groups IIA and the temperature classes T1 to T4.
The external part of the pump tubes between suction orifice
and pressure joint corresponds to category 1.
The external part of the pump tubes between the pressure joint
and the connecting part for a drive motor and the internal part
of the pump tubes in MS variants (covered by the pumped liquid
in case of intended delivery) correspond to category 2.
8.2 Special conditions
When the drum pump is used, all additional components fitted
to the connecting part (coupling, gear, drive motor, etc.) have to
be outside of the mobile container. In this respect, the require-
ments of unit group II (sub-class II A), category 2, temperature
class T4 have to be met.
It has to be ensured that only a stator made of PTFE is built-in.
Caution:
the 75.1 size must not be used to pump flammable
fluids.
The drive motor (electrical or with compressed air drives) may
not exceed an output of 1.0 kW and a speed of 900 1/min.
The drum pump must not be employed for non-mobile opera-
tion. The operation of the pump has to be monitored during
the pumping process so that dry running and empty running
phases are restricted to the absolutely minimum.
8.3 Equipotential bonding and earthing
Before starting up the pump, an equipotential bonding must
be established between the pump, the container to be emptied
and the container to be filled.
The potential between the pump and the container to be emp-
tied is equalized by connecting the equipotential bonding cable
(order no. 0204-994). Paint and dirt should be removed from
the connecting points in order to improve the conductivity.
The conductive connection between the full and empty con-
tainers is achieved by means of a conductive substrate (e.g.
conductive gratings).
The transition between container and earthing must also be
conductive.
Legend:
(1) Equipotential bonding cable, (2a) Conductive substrate or
connection of an equipotential bonding cable to each of the
two drums, (2b) Galvanic connection (low contact resistance
towards earth), (3) Conductive hose, (4) Conductive connection
between hose and hose connector, (5) pump tube category 1/2,
(6) explosion proof motor
8.4 Conductive hoses / hose connections
Anyway the hose connected to the pressure joint of the drum
pump must be sufficiently electrically conductive – with respect
to electrostatic charges.
The ohmic resistance between the fittings – in this case be-
tween the pump tube and the nozzle – may not exceed a limited
value depending on the respective hose type.
1. Identification of the hose with the symbol “M”
Limited value
≤
10 2
Ω
(see Fig 9 -

)
2. Identification of the hose with the symbol „
Ω
“
Limited value
≤
10
6
Ω
(see Fig 9 -

)
The hose connection must ensure a highly conductive transi-
tion between hose and pump tube, as well as between hose
and nozzle.
If this is not the case, all conducting parts (such as the metal
mouth piece at the end of the hose) shall have to be earthed
separately.
Connecting of conductive hoses with armatures to the
hose lines requires the identification and examination
to DIN EN 12 115.