GA01201_1002 - 07/2005
10
Description
The gas ballast valve is opened (position I) and closed (position 0) by tur-
ning the gas ballast knob (7/5) on the front.
To enable the TRIVAC B to be used at intake pressures as high as 1,000
mbar, a special lubricating system was developed featuring force-lubricati-
on of the sliding bearings.
An oil pump (3/6) pumps the oil from the oil reservoir (3/5) into a pressure-
lubrication system which supplies oil to all bearing points (3/2). From there
the oil enters the pump chamber area (2/6) of the vacuum pump.
The oil pump is fitted in the front end plate on the coupling side of the pump
module. The oil suction line is placed low, resulting in a large usable oil
reservoir.
The oil is separated from the gas in the TRIVAC B in two steps as descri-
bed above. First, small droplets are coalesced into large drops in the inter-
nal demister (2/11) fitted above the exhaust valve (2/10). Then, the large
drops fall into the oil reservoir as the exhaust gas is diverted by the inner
walls of the oil case. Thus a low loss of oil is obtained. This and the large
usable oil reservoir ensure long intervals between oil changes even at high
intake pressures.
The vacuum is maintained by the TRIVAC B by an integrated hydropneu-
matic anti-suckback valve (2/3) which is controlled via the oil pressure.
During operation of the TRIVAC B the control piston (4/3) remains sealed
against a spring (4/2) by the oil pressure. The valve disc (4/6) of the anti-
suckback valve is held at the lower position by its own weight (valve open).
When the pump stops (because it has been switched off or because of a
failure), the oil pressure drops and the spring (4/2) presses the control
piston (4/3) up. Thus a connection is provided between the oil case or the
oil reservoir (4/1) and the piston (4/4) of the anti-suckback valve. Due to the
pressure difference between the oil case and the intake port the oil presses
the piston (4/4) up and the valve plate (4/6) against the valve seat (4/5). The
quantity of oil in the oil reservoir (4/1) prevents the entry of air into the inta-
ke port (2/1) at the beginning of this process.
After the oil has flowed out from the reservoir and when the valve plate rests
on the valve seat, air follows in, which vents the pump chamber and forces
the valve disc (4/6) against its seat. This effectively prevents backstreaming
of oil. The anti-suckback valve (2/3) operates independently of the opera-
ting mode of the pump, i.e. also with gas ballast.
Lubrication system
Seperation of oil and gas
Anti-suckback valve
