7. Fault nding
7.1 The pump has f
ailed to start or has stopped
▪ The electrical supply fuse has blown.
▪ The ambient temperature is too high.
▪ The cooling air supply is insucient or is too hot.
▪ The process gas is too hot or the throughput is too high.
▪ The fan is not working or is not connected.
▪ The motor is faulty.
7.2 The pump has failed to achieve the required performance
▪ Gas ballast may be selected. To close gas ballast, turn the control a quarter turn so
that the valve snaps shut. Use this seng to achieve the best possible vacuum. If
the pump has been used to pump condensable vapours or is to pump a large
chamber that has been exposed to atmospheric air (water vapour), it may be
necessary to run for at least an hour on gas ballast.
▪ If the electrical supply voltage is more than 10% below the lowest voltage specied
on the user interface panel, the pump may operate but deliver a degraded vacuum
performance.
▪ There is a leak in the system.
▪ Tip seals may need further run‑in, typic
ally 24 hours, with some requiring up to a
maximum of 100 hours.
▪ The pressure measurement technique or gauge head is unsuitable or gives an
incorrect indicaon of pressure.
▪ The vacuum ngs are dirty or damaged. Replace the ngs.
▪ The inlet strainer is blocked. Clean or replace the strainer.
▪ The c
onnecng pipelines are too long or too small in diameter, conductance.
▪ There is high pressure or a blockage in the exhaust line.
▪ The pump contains traces of process vapours, Run 12 hours with gas ballast.
▪ The pump is outside the specied range of operang condions.
▪ The p seals need replacing.
▪ The pump is in standby mode.
7.3 The pump has poor ulmate vacuum
If the pump exhibits poor ulmate vacuum, refer to Figure: Poor ulmate vacuum ow
chart on page 44.
Page 43
A73501880_G - Fault nding
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