4.9 Vent options, vent valve connection and control
CAUTION: RATE OF INCREASE IN PRESSURE
Risk of damage to equipment. If you vent the pump when it is at full rotational speed
and the rate of increase in pressure is too high, the pump can get damaged and its life
can decrease. We recommend to limit the rate of increase in pressure (refer to
Maximum allowed rate of increase in pressure during venting: pressure against time
(pump initially at full speed) on page 23
) or open the vent valve only after the pump
speed has decreased to 50% of the full rotational speed.
To keep the cleanliness of the vacuum system, we recommend you to vent the pump
before you set the pump (or vacuum system) to off, when the speed of the pump is
between full rotational speed and 50% of the full rotational speed. Between this speed,
the rotor spins sufficiently fast to suppress the back
‑
streaming of hydrocarbon oil from
the backing pump.
Do not connect the vent valve to the backing pipeline to prevent the contamination.
Connect the inlet of the vent valve to the vent gas supply. Refer to
and vent control data on page 22
for the vent gas specification.
To do vent, obey one of the methods given in
to
Alternative valve connected to the vacuum system on page 54
4.9.1 Manual vent valve
A manual vent valve is supplied with the pump. Do not open the manual vent valve too
quickly, as it is not possible to precisely control the rate of increase in pressure using the
manual vent valve. We recommend you to open the manual vent valve only after the
speed of the pump decreases to 50% of the full rotational speed.
4.9.2 TAV5 or TAV6 solenoid vent valve
The TAV5 and TAV6 solenoid valves are available as an accessory. Refer to
. You can use the solenoid valves as follows:
▪
Use a TAV5 or TAV6 solenoid valve in the place of the manual vent valve on the
pump
▪
Use a TAV5 or TAV6 solenoid valve connected to a convenient flange on the
vacuum system
If the vent valve is connected to the vacuum system, select a point upstream of
the pump to prevent the back
‑
streaming of oil from the backing pump.
If you use the TAV5 vent valve, you can hard
‑
vent the pump only when it is at full speed
(if the vacuum system has a volume of five litres or more).
If you use the TAV6 vent valve, you can hard
‑
vent the pump only when it is at full speed
(if the vacuum system has a volume of 10 litres or more).
Install an applicable vent restrictor and vent the pump when it is at full speed or use the
controlled venting option when:
▪
the volume of the vacuum system is less than 5 litres (when using a
TAV5 vent valve) or
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B85200880_D - Installation
