Pfeiffer Vacuum UNO User manual

Rotary Vane Pumps
PD 0010 BE/C (0511)
UNO/DUO 250 A
Betriebsanleitung • Operating Instructions

2
Index
Modifications reserved
1. Safety Precautions .................................. 3
1.1. For Your Orientation........................................................... 3
1.2. Pictogram Definitions........................................................ 3
2. Understanding The Pumps...................... 4
2.1. Main Features..................................................................... 4
2.2. Differences Between The Pump Types.......................... 4
3. Installation ............................................... 5
3.1. Preparations For Installation............................................ 5
3.2. Pump Assembly And Location......................................... 5
3.3. Connecting The Vacuum Side.......................................... 5
3.4. Connecting The Exhaust Side.......................................... 5
3.5. Connecting To The Mains Power Supply....................... 6
3.6. Special Models................................................................... 9
4. Operations .............................................. 10
4.1. Filling Up And Checking The Operating Fluid.............. 10
4.1.2.Operating Fluid F5 ............................................................ 10
4.2. Switching The Pump ON And OFF................................. 11
4.3. Operating The Pump With Gas Ballast Valve.............. 11
4.3.1.Standard Model................................................................ 11
4.3.2 Corrosive Gas Model ....................................................... 11
4.4. Pumping Off Dry Gases................................................... 12
4.5. Pumping Off Vapours....................................................... 12
5. What To Do In Case Of Breakdown...... 12
6. Maintenance .......................................... 13
6.1. Changing The Operating Fluid........................................ 13
6.2. Cleaning The Oil Filter ..................................................... 13
6.3. Re-Setting The Silencer ................................................. 14
6.4. Cleaning The Gas Ballast Valve..................................... 15
6.5. Cleaning The Silencer..................................................... 15
6.6. Shutting Down For Longer Periods............................... 17
7. Service .................................................... 18
8. Technical Data ....................................... 19
8.1. Dimensions........................................................................ 20
9. Accessories............................................ 20
10. Spare Parts ............................................. 20
Declaration Of Contamination .................... 21
Declaration Of Conformity ........... (last page)
Page
Please note:
Current operating instructions are also available via
www.pfeiffer-vacuum.net.

3
Danger of damage to the pump or system.
CAUTION
☞Read and follow all the instructions in this manual.
☞Inform yourself regarding:
☞Hazards which can be caused by the pump;
☞Hazards which can arise in your system;
☞Hazards which can be caused by the medium being
pumped.
☞Avoid exposing any part of your body to vacuum.
☞Observe all safety and accident prevention regulations.
☞Check regularly that all safety requirements are being
complied with.
☞Do not carry out any unauthorised conversions or
modifications on the pump.
☞When returning the pump to us please note the shipping
instructions in Section 7.
1.1. For Your Orientation
Instructions in the text
➡Operating instructions: Here, you have to do something
Symbols Used
The following symbols are used throughout in the illustrations:
Vacuum-flange
Exhaust flange
Gas ballast
Power connection
Position-Numbers
Identical pump and accessory parts have the same position
numbers in all illustrations.
Danger of injury
from moving parts.
WARNING
Danger of personal injury.
WARNING
1. Safety Precautions
1.2. Pictogram Definitions
Important note.
☞
PLEASE NOTE
Danger of burns from touching hot parts.
WARNING
Danger of an electric shock.
WARNING
Danger of poisoning.
DANGER

4
2.1. Main Features
2. Understanding Pumps
2.2. Differences Between The Pump Types
Type Stage Nominal Attainable
flow rate Final Pressure
at 50 Hz (Total, without
Gasballast)
UNO 250 A one stage 267 m3/h < 5.0 •10-2 mbar
DUO 250 A two-stage 267 m3/h < 3.0 •10-3 mbar
The UNO 250 A is a single stage and the DUO 250 A is a two
stage rotary vane pump.
Special features:
– Pressurised oil lubrication
– Hydraulically controlled high vacuum safety valve
– Optional: Oil filter systems, Condensate separator,
Operational monitoring systems.
Proper Use
– Rotary Vane Vacuum Pumps may only be used to generate
vacuum.
– Installation, start-up, operating and maintenance
instructions must be observed.
– Accessories other than those named in this manual may
not be used without the agreement of Pfeiffer Vacuum.
Special Models
Helium tight model:
– Operating Fluid P3
– Leak rate < 1 •10-5 mbar l/s
– Additional radial shaft seal (total of 3) with sealing oil
chamber (oiler)
– Option: Special gas ballast valve for inert gas inlet (N2) to
prevent atmospheric air entering the system.
Korrosivgasausführung:
– Operating fluid F5
– Leak rate < 1 •10-5 mbar l/s
– Additional radial shaft seal (total of 3) with sealing oil
chamber (oiler)
– Vanes and sight glasses made from special materials.
– Option: Special gas ballast valve for inert gas inlet (N2) to
prevent atmospheric air entering the system.
Improper Use
The following are regarded as improper:
– The pumping of corrosive gases (except with corrosive
gas processes version).
– The pumping of gases which are contaminated with
particles, dust and condensate. Avoid condensation and
sublimation; take note to the vapour compatability.
– The pumping of explosive gases.
– Operating the pump in locations where there is an explosi-
on hazard.
– The Rotary Vane Vacuum Pumps may not be used for the
purpose of generating pressure.
– The pumping of liquids.
– Uses not covered above, and, in particular:
– Connection to pumps and units which is not permitted
according to their operating instructions.
– Connection to units which contain touchable and voltage
carrying parts.
Improper use will cause any rights regarding liability and
guarantees to be forfeited.
Rotary Vane Vacuum Pumps UNO 250 A, DUO 250 A
1 Vacuum flange,
2 Exhaust flange,
3 Motor,
5 Control voltage connection (for pump monitoring)
15 Casing
18 Baffle Plate
28 Support Stand
42 Operating fluid filler screw
43 Operating medium drain screw
44 Sight glass
45 Gas ballast valve, complete;
46 Screw plug
182 Pressure gauge
183 Cover for filter cleaning
205 Screw plug for adjusting the silencer
15 205 42 183 46 1 2 182 45
44 43 18 5 28 3

5
3.4. Connecting The Exhaust Side
Pressure can rise to dangerous levels in
exhaust lines.
Lay exhaust lines without built-in shutoff
devices. If a shut-off device is installed for
internal operating reasons or if there is a risk of
excess pressure developing in the lines, official accident
prevention regulations must be complied with.
The exhaust line diameter should not be less than 63 DN.
The line from the pump must be laid with a downward
gradient so that condensate is prevented from flowing back
into the pump. Otherwise a trap must be installed.
Auspuffleitung nicht kleiner als DN 100 von der Pumpe aus
fallend verlegen, damit kein Kondensat in die Pumpe
zurückläuft. Andernfalls Abscheider einbauen.
Der Auspuffdruck darf 1,5 bar nicht überschreiten.
Expelled gases and vapours can represent a
hazard to health and/or the environment.
For this reason the relevant regulations must
always be complied with when working with
toxic substances. Only officially approved filters
may be used for the separation of such substances. This also
applies when handling toxic or chemically unstable gases
and to gases susceptible to polymerisation or to the formation
of peroxide (see 9. Accessories).
WARNING
CAUTION
3. Installation
3.1. Preparations For Installation
Do not carry out any unauthorised conversions
or modifications on the pump.
Fill up with operating fluid before operating the
first time (included in a separate pack in the
delivery consignment). When transporting use
only the eyebolts provided for the purpose.
3.2. Pump Assembly And Location
➡Where stationary installation is involved, anchor the pump
on site.
➡Sight glass 44 on the front side must be visible and gas
ballast valve readily accessible.
When filled with operating fluid, do not tilt the
pump otherwise operating fluid could escape
via the exhaust opening.
➡When installing the pump in a closed housing, ensure
there is sufficient air circulation.
CAUTION
CAUTION
WARNING
3.3. Connecting The Vacuum Side
➡Keep the connection between the vacuum chamber and
pump as short as possible.
➡Remove all scaling and loose particles from welded lines
prior to assembly.
– To protect the pump, separators, filters and cooling traps
etc.(see Section 9. Accessories) can be fitted upstream of
the pump. However, the conductance value of the
accessory causes a reduction in volume flow rate.
Where rotary vane vacuum pumps are
anchored, no forces from the piping system
should be allowed to act on the pump.
Suspend, decouple or support all piping
concerned with the pump.
CAUTION
44
Maximum angle of inclination to each side 10Þ
Maximum erection height 2000 m N.N.
Ambient temperature maximum 40 °C and minimum 12 °C
Maximum relative humidity 85%

6
3.5. Connecting To The Mains Power Supply
Power connections must comply with local
regulations. Voltage and frequency information
given on the rating plate must correspond to
the mains voltage and frequency values.
When the electrical connections have been
completed, carry out the earthed conductor
test.
The pump must be disconnected from the power before
opening the terminal box.
When switching on for the first time, check the direction of
rotation:
Checking The Direction Of Rotation
Check the direction of rotation of the pump
before filling up with operating medium.
➡Remove blank flange on the exhaust flange,
– do not take off sieve strainer from vacuum flange 1 and
exhaust flange 2.
➡Switch on pump for a short time (max. 3 seconds).
Motor/motor fan must turn clockwise (see arrow P on
motor fan cover).
➡If direction of rotation is incorrect: Interchange two
phases on the connecting cable.
CAUTION
WARNING
Power section with motor to be protected
Checking The Direction Of Rotation
P
Three phase motors with PTC
Pumps fitted with these motors are used primarily in systems
or in closed rooms. The motors of these pumps are fitted with
three PTCs which are built into the stator windings. The
connection of a tripping unit will protect the pump against
overloading (see connection example).
Tripping unit:
PTC tripping unit with two switchover contacts at the output
manufactured by Ziehl, type MSR 220 F (see Section 9,
„Accessories“), AEG type TMA 4R or Siemens type 3 UN8 004.

7
N
L1
M
3
L2
L3
F1 - F3
K1
10 11
AC 220 ... 240 V
Us F4
UVW
S1
S2
k1
K1
H1
S3
2)
A1 A2 T1 T2 Y2Y1 24 21 22 14 1211
2) 2) 1) 1) 1)
PP1008/k
T1...T3
3)
Connection example for water cooled canned motors with Tripping unit (typ MSR 220 F, order no.: P 4768 051 FQ
USControl Voltage
S1 Pressure key „OFF“
S2 Pressure key „ON“
S3 Control switch (reset key)
K1 Motor contactor
F1 ... F4 Fuses
T1... T3 Temperature sensors
H1 Signal lamp
M Motor, 3-phase
1) Only for units with two relais
outputs
2) Only for type MSR
3) Only for order no. P 4768 051 FQ
Tripping Units Type MSR save the switch-off occuring on thermal overload and it is necessary to manually reset via the integrated key or via the
externally connected key S3 to switch back on. Switching on via the mains is automatically recognised as a reset.
Voltage see rating plate
The Three Phase Current Motor Circuit
The three phase motor winding consists of three identical
coils.
Delta Connection
The three coils are connected in series with the connection
point connected to the mains. The voltage of each coil is the
same as the mains voltage whereas the mains current is the
cube root of the coil current. Delta connections are denoted
by the symbol ∆∆.
The voltage between the mains supply lines is called mains
voltage. The mains current is the current which flows in the
supply lines.
Star Connection
The ends of the three coils are connected at the star center.
The terminal voltage is the cube root of the coil voltage; the
mains and the coil current are the same. Star connections are
denoted by the symbol Y.
A star connection three phase motor for 400 V mains voltage
has a coil voltage of 230 V.
W2 U1
L1
V2 V1
W1 U2
L3 L2
W2 U2 V2
U1 V1 W1
L1 L2 L3
W2
U1
L1
V2
V1
W1
U2
L3 L2
W2 U2 V2
U1 V1 W1
L1 L2 L3
Motor coil and connecting plate of Delta Connection Motor coil and connecting plate of Star Connection

8
Helium tight and corrosive gas models UNO/DUO 250 A
45 Gas ballast valve
118 Radial shaft seal
122 Armature
126 O-ring
128 O-ring
132 Support washer
133 Radial shaft seal
134 Double supporting ring
135 Spacer
136 Oiler
138 O-ring
168 O-ring
169 Locking screw for connecting the gas ballast valve
(when no valve is fitted)
45/169
122
132
133
135
126
128
118
134
136
168
138
Important: The instructions in 4.1.2. must be
observed when working with synthetic
operating medium F5.
CAUTION
Oiler 136 should always be filled to the half way
mark, maximum, (when the pump is cold); top
up as necessary. When the pump becomes
warm, the lubricant expands and can spill over
if the oiler is too full.
CAUTION

9
3.6. Special Models
Helium Tight Models
– Helium tight models are distinguished by their high level
tightness to the atmosphere.
– Helium tight models are operated, as standard, with opera-
ting medium P3.
– The rotor shaft is sealed with an additional radial shaft
seal. The cavity between the radial shaft seals 133 is filled
with operating medium and is supplied by the oiler 136.
– If the gas ballast valve 45 is not available, the opening
should be closed with the locking screw 169 or a special
gas ballast valve with dosing device and hose connection
for flushing gas is available (on request).
Corrosive Gas Models
– Corrosive gas models are manufactured with special
materials.
– The rotor shaft of both versions is sealed with an
additional radial shaft seal. The cavity between the radial
shaft seals 118 and 133 is filled with operating medium and
is supplied by the oiler 136.
– If the gas ballast valve 45 is not available, the opening
should be closed with the locking screw 169 or a special
gas ballast valve with dosing device and hose connection
for flushing gas is available (on request).
– Corrosive gas models are operated, as standard, with
synthetic operating medium F5.

10
4.1. Filling Up And Checking The Operating
Fluid
Standard version pumps are tested with opera-
ting fluid P3. Guarantees relating to attainment
of final pressures and trouble free functioning
apply only providing this operating fluid is used.
The delivery consignment contains sufficient operating fluid
for one filling (valid only for P3).
Pumps for special applications (e.g. for pumping corrosive
gases) can be operated with special operating fluids such as
F5 and other Pfeiffer Vacuum operating fluids. The use of
such operating fluids requires prior authorisation from the
manufacturer.
P3 must be disposed of in accordance with local waste dispo-
sal regulations.
➡Remove operating fluid filler screw 42.
➡Fill up with operating fluid included in the consignment
(only for P3); refer to rating plate for correct quantity.
➡Replace operating fluid filler screw 42; be careful with the
O-ring.
CAUTION
➡Check operating fluid level only when the pump is warm
and running and vacuum connection 1 and gas ballast
valve are closed.
➡The level of operating fluid must always be between the
top and the middle of the sight glass 44.
➡Topping up operating fluid is possible when the pump is
running and in final vacuum operations.
➡In non-stop operations check operating fluid daily,
otherwise whenever the pump is switched on.
4. Operations
Rotary Vane Vacuum Pumps UNO/DUO 250 A
1 Vacuum flange,
2 Exhaust flange,
3 Motor,
5 Socket for control voltage
15 Casing
28 Support stand
42 Operating fluid filler screw
43 Operating medium drain screw
44 Sight glass
45 Gas ballast valve, complete;
182 Pressure gauge
183 Cover for filter cleaning
15 42 1 2 182 45
44 43 18 5 28 3
Sight glass 44
Operating fluid
level for the first
filling and during
operation
4.1.2. Operating Fluid F5
Only the synthetic operating fluid F5 may be used for corrosi-
ve gas model pumps. The use of other operating fluid must be
cleared by the manufacturer.
When working with synthetic operating media,
the manufacturer’s directions must be
observed.
If ‘’F5’’ is heated above 250°C, toxis vapours
which can harm the airways are given off.
Do not allow ‘’F5’’ to come into contact with tobacco products
(danger of poisoning when ignited). The precautions
necessary in the handling of chemicals must be observed.
Operating fluids containing toxic or aggressive
substances require special treatment. The
instructions for handling such media must be
observed.
Never fill into pumps which contain mineral oil
residues.
If there is a noticeable loss of operating fluid,
the radial shaft seals should be checked.
If operating fluid is leaking out underneath the
casing 15 from the opening between the
support stand 28 and motor 3, the radial shaft
seal must be replaced. Please contact your local Pfeiffer-
Service (see Section 7.).
☞
PLEASE NOTE
CAUTION
DANGER
WARNING

11
4.2. Switching The Pump ON And OFF
When operating the pump gets hot.
The pump can be switched ON and OFF in any pressure
range. On switching off, the built-in high vacuum safety valve
to the vacuum plant closes automatically and vents the pump.
Minimum start-up temperature, in compliance with German
Industrial Standard DIN 28 426: + 12 °C.
On switching OFF (intake pressure < 750 mbar) the built-in
high vacuum safety valve to the vacuum chamber closes
automatically and the pump is vented.
WARNING
4.3. Operating The Pump With Gas Ballast
If condensable vapors are pumped off, the pump must always
be operated with gas ballast. If the condensation exceeds the
water vapor capacity of the pump, a condenser should be
connected upstream. If no condenser is connected, the
condensate produced due to the difference in temperature
between the pump housing and pump body must be drained
at drain plug 43. The condensate produced inside the pump
can be observed at sight glass 44 as a rising operating fluid
level.
4.3.1. Standard Model
Gas ballast valve 45 is fitted with a sliding sleeve which, when
pushed towards the pump, opens the valve and when pushed
away from the pump, shuts the valve. Intermediate settings
are not possible.
4.3.2 Corrosive Gas Model
Gas ballast valve 45 is fitted with a dosing device and a
flushing gas connection. It has a sliding sleeve which opens
the valve when pushed towards the pump and shuts the valve
when pushed away from the pump. The dosing device is
closed when the groove in the dosing screw is in the horizon-
tal position; in the vertical position the dosing device is fully
open. A flow meter enables any intermediate gas volume
setting between fully open and fully closed to be made.
Flushing gas must be connected when
operating corrosive gas version pumps. The gas
ballast valve must be open. Flushing gas
pressure may not exceed 1.5 bar. Our
specialists would be pleased to give advice
regarding the type and volume of flushing gas required.
☞
PLEASE NOTE
Gas ballast valve standard model
28 Support stand
45 Gas ballast valve with sliding sleeve
182 Pressure gauge
182 45
28
When the pump is at operating temperature, the pressure
gauge 182 indicates a operating fluid pressure between 0.8
and 2.5 bar. At a cold start (approx. 12°C), the pressure in the
pressure gauge may rise up to max. 6 bar. When the pump
temperature rises, the pressure drops to normal.
With operating medium F5, the pressure of the pump at
working temperature is set between 3 and 5 bar. When cold
starting, pressure rises upto 15 bar.
In continuous operation the level of operating fluid must be
checked daily at the sight glass 44 and the pressure at
pressure gauge 182.

12
4.4. Pumping Off Dry Gases
No special measures are necessary. The gas ballast valve
may remain closed.
5. What To Do In Case Of Breakdown?
Problem Possible Causes Remedy
Pump doesn't attain final pressure Pump dirty Operate pump for a longer period with open
Operating fluid dirty gasballast valve or change operating fluid
Leak in system Repair leak
Unusual operating noises Damaged pump stages Request repair by Pfeiffer Vacuum Service
Damaged coupling piece Request repair by Pfeiffer Vacuum Service
Oil leaking from the foot of the pump Radial shaft seal defective Request repair by Pfeiffer Vacuum Service
Pump doesn't start Ambient temperature < 12 °C Warm up pump
Dirty pump stages Request cleaning by Pfeiffer Vacuum Service
Damaged pump stages Request repair by Pfeiffer Vacuum Service
Further repairs can only be carried out by trained specialists in accordance with Service Instructions.
Gasballast valve helium tight and corrosive gas models
4.5. Pumping Off Vapours
To prevent their condensation in the pump,
vapours should only be pumped off with the
pump at operating temperature and the gas
ballast valve 45 open.
Observe pump water vapour tolerance levels
(see Section 8.0 Technical Data). When the process has been
completed, allow the pump to continue running for approx. 30
minutes for operating medium cleaning purposes.
CAUTION

13
➡Drain off remaining operating fluid.
➡In the case of serious contamination, the operating fluid
will have to be changed several times.
➡Screw in operating fluid drain screw 43 with O-ring.
When carrying out servicing work, take the following
precautions:
Always ensure the pump cannot be switched
on when carrying out any work on the pump. If
necessary, remove the pump from the system to
carry out inspection work.
➡Only dismantle the pump as far as is necessary in order to
repair defects.
➡Dispose of used operating fluid in compliance with local
regulations.
➡When working with synthetic operating media, toxic
substances and substances contaminated with corrosive
gases, the relevant instructions governing their use must
be observed.
➡Only use benzine or similar agents for cleaning pump
parts. Do not use soluble cleaning agents.
6.1. Changing The Operating Fluid
The rate of deterioration of the operating fluid depends on the
pump applications.
➡The level of deterioration of organic operating fluids (for
example P3) can be read off from the colour scale in
accordance with DIN 51578 on the supplementary sheet
PK 800 219 BN/B, on request.
– The colour scale enables precise colour determination.
➡Fill a specimen in a test tube or some similar vessel and
test by holding against the light.
➡Where the discolouration is dark yellow to red brown
(equivalent to 4 ... 5 on the scale) change operating fluid.
Where organic operating fluids, for example P3,
are involved, the operating fluid should be
changed every 8000 h; at least once a year!
Replacing The Operating Fluid
➡Switch off the pump.
➡Unscrew operating fluid drain screw 43 and drain
operating fluid.
The operating fluid temperature can be as high
as 80 °C. During maintenance and repair work,
process related toxic gases and vapours can
escape from the operating fluid which may
become contaminated with harmful substances
(radioactive, chemical etc.).
Disposal of used operating fluid is subject to the relevant
regulations.
➡Screw in operating fluid drain screw 43.
➡Allow pump to run for about 10 seconds with open vacuum
flange.
WARNING
CAUTION
WARNING
6. Maintenance
6.2. Cleaning The Oil Filter
Also clean the oil filter 181 every time you chan-
ge the pump fluid.
➡Unscrew screws 184 and remove the cover 183, take care
with the o-ring.
➡Unscrew screws 185 and lift the oil filter 181 out of the
pump on flange 186.
➡Dismantle the oil filter as shown below and clean the star-
shaped filtering sieve 187 in benzine (naphtha) or similar
cleaning agent.
➡Reassemble in reverse order.
Filling in operating fluid
➡Check the drain plug 43 for tight seat.
➡Remove operating fluid filler screw 42.
➡Fill up the new operating fluid; refer to rating plate for
correct quantity (UNO 250 A --> 30 l, DUO 250 A --> 23 l).
➡Replace operating fluid filler screw 42; be careful with the
O-ring.
➡Check operating fluid level at the sight glass as per
section 4.1..
Operating fluid can contain substances from
the medium pumped. Operating fluid must be
disposed of in accordance with the local
respective regulations.
Please request safety instruction data sheets for operating
fluids from Pfeiffer Vacuum.
WARNING
☞
PLEASE NOTE

14
6.3. Re-Setting The Silencer
If the silencer 13 is not functioning, a knocking noise
becomes audible at end vacuum. This does not cause
damage to the pump but it may be disturbing in quiet rooms.
Setting can be carried out while the pump is running and the
intake socket and gas ballast valve are closed, using a normal
screwdriver:
➡The pump must have reached its operating temperature.
➡Remove locking screw 46 (UNO 120A) or operating fluid
filler screw 42 (DUO 250 A).
➡Using a screwdriver, open the valve spindle 47 approx. 3
turns (flushing) for some seconds and then close it again
completely (clockwise).
➡Slowly open the valve spindle 47 (1/2 to a complete turn)
until the knocking noise is no longer audible.
➡Replace locking screw 46 or operating fluid filler screw 42
paying attention to the O-ring.
42 46
Adjusting the silencer
42 Screw plug of the silencer (DUO 250 A)
46 Screw plug of the silencer (UNO 250 A)
Dismantling and cleaning the oil filter
1 Vacuum flange,
2 Exhaust flange,
42 Operating fluid filler screw
43 Operating fluid drain screw
44 Sight glass
45 Gas ballast valve, complete;
181 Ölfilter, komplett
183 Cover for filter cleaning
184 Screw (4 pieces) 185
186
187
188
189
190
205 42 184 183/ 1 2 45
191
44
43
181
185 Screw
186 Flange
187 Star-shaped filtering sieve
188 Spacer sleeve
189 Washer
190 Screw
191 O-ring
205 Screw plug for adjusting the silencer

15
Dismantling and assembling the Helium Tight and Corrosive
Gas Models
➡Unscrew valve housing 68 at hexagon nut, take care with
the O-ring 31; if necessary proceed as follows:
– Remove circlip 59 and pull off sleeve 61, insert round
steel bar into boring and remove valve housing 68
taking care with the O-ring 31.
➡Remove circlip 67 and dosing insert 66 from dosing valve
body 64.
➡Clean all parts.
➡Check O-rings 65 and 69 for wear and replace if necessary.
➡Lightly oil O-rings with operating fluid.
➡Re-assemble the parts in reverse order.
6.4. Cleaning The Gas Ballast Valve
Gas ballast valve 45 can only get dirty if the ambient air
sucked in is dusty.
Dismantling and assembling the Standard Model
➡Unscrew valve housing 68 at hexagon nut, take care with
the O-ring 31; if necessary proceed as follows:
· Remove circlip 59 and pull off sleeve 61, insert round
steel bar into boring and unscrew valve housing 68
taking care with the O-ring 31.
➡Clean all parts.
➡Check both o-rings 60 for wear and replace if necessary.
➡Lightly lubricant o-rings with operating fluid.
➡Re-assemble the parts in reverse order.
6.5. Cleaning The Silencer
Dismantling and assembling
➡Remove the silencer 47 ... 50 and 129 in axial direction and
clean it.
➡Check o-rings 48 and 49, valve spindle 47 and valve seat in
13 for wear, replace if necessary.
➡Reassemble in reverse order.
Carefully push o-ring 48 into the groove in part 47 and light-
ly lubricate with operating fluid. The o-ring 49 must be
fitted around part 129.

16
47
48
50
49
129
51
52
56
54
55
51
52
53
179
58
57
174 31 28 34
61
59
68
60
174 28 31 68 66 62
34 70 69
63
64
65
67
59
Gas balllast devices and silencer Gas ballast inlet valve 45 for standard models
Gas ballast inlet valve 45 for
helium-tight and corrosive gas models
13 Silencer
14 Non-return valve
28 Support stand
31 O-ring
34 Cover
47 Valve spindle
48 O-ring
49 O-ring
50 Valve housing
51 Plate spring
52 Screw
53 O-ring
54 Screw
55 Insert
56 Screw
57 O-ring
58 Centering sleeve
59 Circlip
60 O-ring
61 Sleeve
62 Flushing gas connection
63 O-ring
64 Dosing valve unit
65 O-ring
66 Dosing insert
67 Circlip
68 Valve housing
69 O-ring
70 Rohr
129 Centering ring
174 Screw connection
179 Housing non-return valve

17
6.6. Shutting Down For Longer Periods
Should the pump have to be shut down for an longer period,
the complete pumping system must be adequately protected
against corrosion.
➡Switch off pump.
➡Unscrew operating fluid drain screw 43 and drain
operating fluid as per Section 6.1.
➡Screw in operating fluid drain screw 43; keep an eye on
the position of the O-ring.
➡Allow pump to run for about 10 seconds with open vacuum
flange. .
➡Drain off remaining operating fluid.
➡Fill up pump with fresh operating fluid:
Filling: UNO 250 A --> 21 l
DUO 250 A --> 18 l
If this amount of operating fluid is filled in, the level is
extremely high but this is necessary to protect all parts of the
pump against corrosion.
Before operating, the operating fluid must be
reduced to its normal level.
CAUTION

18
7. Service
Do Make Use Of Our Service Facilities
In the event that repairs are necessary to your pumping
station, a number of options are available to you to ensure
any system down time is kept to a minimum:
– Have the pump repaired on the spot by our Pfeiffer
Vacuum Service Engineers;
– Return the individual components to the manufacturer for
repairs;
– Replace individual components with a new value
exchange units.
Local Pfeiffer Vacuum representatives can provide full
details.
Before Returning:
➡When returning the pump please use original factory
packing.
➡Dismantle all accessories.
➡Drain operating fluid.
➡If the pump is free of harmful substances, please attach a
clearly visible notice: “Free of contamination” (to the unit
being returned, the delivery note and accompanying
paperwork).
Harmful substances" are substances and preparations as
defined in current legislation. Pfeiffer Vacuum will carry out
the decontamination and invoice this work to you if you have
not attached this note. This also applies where the operator
does not have the facilities to carry out the decontamination
work. Units which are contaminated microbiologically, explo-
sively or radioactively cannot be accepted as a matter of
principle.
Fill Out The Contamination Declaration
➡In every case the "Contamination Declaration" must be
completed diligently and truthfully.
➡A copy of the completed declaration must accompany the
unit; any additional copies must be sent to your local Pfeif-
fer Vacuum Service Center.
Please get in touch with your local Pfeiffer Vacuum represen-
tatives if there are any questions regarding contamination.
Decontaminate units before returning or possi-
ble disposal. Do not return any units which are
microbiologically, explosively or radio-
actively contaminated.
Returning Contaminated Units
If contaminated units have to be returned for
maintenance/repair, the following instructions concerning
shipping must be followed without fail:
➡Neutralise the pump by flushing with nitrogen or dry air.
➡Seal all openings to the air.
➡Seal pump or unit in suitable protective foil.
➡Ship units only in appropriate transport containers.
WARNING
Repair orders are carried out according to our
general conditions of sale and supply.
➡If repairs are necessary, please send the unit together
with a short damage description to your nearest Pfeiffer
Vacuum Service Center.
☞
PLEASE NOTE

19
Single stage Unit UNO 250 A
Two stage DUO 250 A
Connection nominal diameter
Inlet ISO-F DN 100 DN 100
Outlet ISO-F DN 100 DN 100
Rated volume flow rate at
50 Hz m3/h 267 267
60 Hz m3/h 320 320
Volume flow rate
50 Hz m3/h 250 250
60 Hz m3/h 300 300
Final pressure
total without gas ballast mbar < 5.0 •10-2 < 3.0 •10-3
total with gas ballast mbar < 1 < 6.0 •10-3
Auspuffdruck min mbar > 250 > 250
Auspuffdruck max mbar < 1500 < 1500
Water vapour compatibility
50 Hz mbar 33 25
60 Hz mbar 33 25
Water vapour acceptable capacity
50 Hz g/h 5100 4350
60 Hz g/h 6000 5200
Emission sound pressure level
without gas ballast dB(A) 75 75
Operating fluid, amount l 30 23
Max. admissible operating temperature 1) °C 90 90
Nominal rotation speed of pump
at 50 Hz 1/min 975 975
at 60 Hz 1/min 1175 1175
Nominal motor power for
three phase motor
with temperature sensor at 50 Hz kW 7,5 7,5
at 60 Hz kW 7,5 7,5
Weight pump with
three-phase motor. kg 375 410
1) The maximum admissible operating temperature of 90 °C is valid for an ambient temperature of 25 °C and
operating fluid P3, without gas ballast.
Operating temperatures in the range of 110 ... 115 °C could be caused by increased ambient temperature to
max. 40 °C (for operating fluid P3).
8. Technical Data

20
8.1. Dimensions
9. Accessories
10. Spare parts
A comprehensive range of accessories can be found in the
Pfeiffer Vacuum catalogue, to:
– extend the application range of the pumps and
– protect the pump from wear, when used under extreme
operating conditions.
The tripping device to protect against overloading the pump
can be ordered under the order number P 4768 051 FQ.
When ordering accessories and spare parts please be sure to state the full part number. When ordering spare parts please state
additionally the unit type and unit number (see rating plate). Please use this list as an order form (by taking a copy).
Pos. Description Quantity Size Number Comment Order Quantity
Set of seals, Standard-version 1 PK E00 016 -T
Set of seals, C- und H-version 1 PK E00 017 -T
1 Sight glass, standard-version 1 R 15’’ PK 213 140
1 Sight glass, C- and H-version 1 R 15’’ PK 214 131 AX
2 Gas ballast valve, standard-version 1 PK 216 136 -U
2 Gas ballast valve, C- and H-version 1 PK 216 142 -U
5 Socket with PCB 1 PK 215 306 -X
29 Sieve insert 2 DN 100 ISO PK 300 044 -X
Tripping unit P 4768 051 FQ