BOC E2M28, Инструкция по эксплуатации

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E2M28 and E2M30 Rotary Vacuum Pumps
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Issue K 24 Jul 05
4.1.3 Gas purges
Switch on the inert gas purge to remove air from the pump and the exhaust pipeline before the process
starts. Switch off the purge flow at the end of the process only after any remaining flammable gases or
vapours have been purged from the pump and exhaust pipeline.
If liquids that produce flammable vapours could be present in the pump foreline, then the inert gas purge
to the 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 you calculate 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 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.
Continually measure the inert gas purge flow rate: if the flow rate falls below that required, you must
stop the flow of flammable gases or vapours into the pump.
Note: We recommend that you obtain and read the Vacuum Pump and Vacuum System Safety manual
(publication number P300-20-000), available from BOC Edwards or your supplier.
4.2 Gas-ballast control
Use the gas-ballast control (Figure 1, item 3) to change the flow of gas-ballast into the low vacuum stage
of the pump, and to provide an additional oil-feed to the pump mechanism.
Use the gas-ballast control closed:
• To achieve ultimate vacuum.
• To pump dry gases.
Turn the gas-ballast control six turns anti-clockwise to open it fully. Use the gas-ballast control open:
• To pump high concentrations of condensable vapour.
• To decontaminate the oil.
When you operate the pump with the gas-ballast control open, there will be an increased rate of oil loss
from the pump. Ideally, a mist filter and oil return kit should be used on clean applications.
WARNING
If you use inert gas purges to dilute dangerous gases to a safe level, ensure that the pump
is shut down if an inert gas supply fails.
WARNING
You must obey the instructions and take note of the precautions given below, to ensure
that pumped gases do not enter their flammable ranges.