BOC Edwards A730-01-983, Инструкция по эксплуатации, Страница: 22 / 44

Issue A Nov 02
PAGE
16
XDS Dry Pump
OPERATION
16
4.4 To pump condensable vapours
Select a suitable gas ballast setting (gas ballast control
in position 'I' or 'II') when there is a high proportion
of condensable vapours in the process gases. This
will assist the vapours to pass through the pump
without condensing and keep the pump performance
from degrading.
4.5 To pump flammable gases
The XDS35i pump must not be used in an area
where flammable gases, vapours or dust are present
or could be present.
When using the XDS pump for pumping flammable
gases and/or vapours the pump mechanism must be
considered to be a source of ignition.
• Ensure the system is leak tight.
• Dilute any flammable gases or vapours by
using an inert gas purge (e.g. N
2
) to the pump
inlet and/or gas ballast (accessory available) to
reduce their concentration in the pump and
exhaust line to less than one quarter of their
published lower explosive limits (lel).
• Prevent the condensation of flammable
vapours within the pump mechanism and
exhaust line by using an inert gas purge to the
pump gas ballast connection.
WARNING
Do not use the XDS pump for
pumping flammable gases, gas
mixtures or vapours that are within
their flammable range.
CAUTION
The following actions must be taken to ensure that
the gas being pumped stays out of the flammable
range.
• The inert gas purge should be switched on to
remove air from the pump and exhaust before
the process starts. The purge flow can be
switched off at the end of the process only
after any remaining flammable gases or
vapours have been purged from the pump and
exhaust line.
• If liquids that produce flammable vapours
could be present in the pump foreline then the
inert gas purge to the XDS pump should be
left on all the time this liquid is present.
Flammable liquids could be present in the
foreline as a result of condensation or may be
carried over from the process.
• When calculating the flow rate of inert gas
required for dilution, consider the maximum
flow rate for the flammable gases/vapours that
could occur. For example, if a mass flow
controller is being used to supply flammable
gases to the process, you should assume a
flow rate for flammable gases that could arise
if the mass flow controller is fully open. The
inert gas purge flow rate should be continually
measured and if the flow rate falls below that
required, then the flow of flammable gases or
vapours to the pump must be stopped.
We recommend you obtain and read Vacuum
Pump and Vacuum System Safety publication
no P300-20-000 available from BOC Edwards
or your supplier.
4.6 Remote operation using 15 way D
connector
It is possible to operate the pump remotely using the
15 way D type connector fitted on the panel at the
side of the pump. (Refer to Figure 1).
The 15 way D connector is insulated to ensure that
it remains protected in the event of a single fault
condition.