Sera 409.2 Series User manual

* available until 31.12.2016
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2Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
Content
1. General .........................................................................................................................................................4
1.1 General user information.................................................................................................................4
1.2 Symbols and notes used in these operating instructions ................................................................4
1.3 Notes attached to the product .........................................................................................................4
1.4 Quality instructions..........................................................................................................................5
2. Safety instructions ...................................................................................................................................... 5
2.1 Personnel qualication and training ................................................................................................5
2.2 Dangers in case of inobservance of the safety instructions ............................................................5
2.3 Safety conscious working................................................................................................................5
2.4 Safety instructions for owner / operator ..........................................................................................6
2.5 Safety instructions for maintenance, servicing and installation work ..............................................6
2.6 Arbitrary modication and production of spare parts.......................................................................6
2.7 Improper operations ........................................................................................................................6
2.8 Intended use ...................................................................................................................................6
2.9 Operating conditions .......................................................................................................................7
2.10 Personal protection for maintenance and service .........................................................................7
2.11 Utilities/Lubricants .........................................................................................................................7
2.12 Foreseeable misuse......................................................................................................................8
2.12.1 Transport ....................................................................................................................................8
2.12.2 Assembly and installation...........................................................................................................8
2.12.3 Start-up ......................................................................................................................................8
2.12.4 Operation ...................................................................................................................................8
2.12.5 Maintenance/Repair ...................................................................................................................9
2.12.6 Cleaning .....................................................................................................................................9
2.12.7 Shut-down ..................................................................................................................................9
2.12.8 Disassembly...............................................................................................................................9
2.12.9 Disposal .....................................................................................................................................9
3. Transport and storage...............................................................................................................................10
3.1 General .........................................................................................................................................10
3.2 Transport .......................................................................................................................................10
3.3 Storage..........................................................................................................................................10
4. Product description................................................................................................................................... 11
4.1 Types............................................................................................................................................. 11
4.1.1 Type key..................................................................................................................................... 11
4.1.2 Type plate...................................................................................................................................12
4.2 Materials........................................................................................................................................12
4.3 Viscosity, pumped medium............................................................................................................ 12
4.4 Dosing range.................................................................................................................................12
4.5 Noise measurement ......................................................................................................................12
4.6 Assembly groups of the piston diaphragm pump .......................................................................... 13
4.7 Functional description ...................................................................................................................14
4.7.1 General ......................................................................................................................................14
4.7.2 Stroke mechanism .....................................................................................................................14
4.7.3 Driving motor..............................................................................................................................14
4.7.4 Stroke length adjustment ...........................................................................................................14
4.7.5 Assembly pump..........................................................................................................................17
4.7.6 Pump body .................................................................................................................................18
4.7.7 Suction-/Pressure valve .............................................................................................................19
4.7.8 Stroke frequency transmitter (option).........................................................................................19
4.7.9 Diaphragm rupture monitoring ...................................................................................................20
5. Technical Data ...........................................................................................................................................22
5.1 Output data ...................................................................................................................................22
5.2 Motor data ....................................................................................................................................23
5.3 Dimensions ...................................................................................................................................24

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TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
6. Assembly / Installation.............................................................................................................................26
6.1 Provide for an overpressure protection .........................................................................................28
6.2 Preventing a backow of the pumped medium .............................................................................29
6.3 Eliminating undesired siphoning ...................................................................................................29
6.4 How to ensure suction free from air ..............................................................................................30
6.5 Install the empty-tank alarm ..........................................................................................................30
6.6 How to avoid an emptying of the suction line................................................................................31
6.7 Line strainer ..................................................................................................................................31
6.8 Suction via a siphon vessel...........................................................................................................32
6.9 In case of easily degassing pumped media ..................................................................................32
6.10 Dosing of suspensions ................................................................................................................33
6.11 Damping of the pulsation.............................................................................................................33
7. Electrical connection / Interfaces ............................................................................................................ 35
7.1 Motor connection...........................................................................................................................35
7.2 Direction of rotation .......................................................................................................................35
7.3 Terminal box.................................................................................................................................. 35
7.4 Motor protection ............................................................................................................................35
8. Operation in explosion-hazardous areas................................................................................................ 36
8.1 Identication ..................................................................................................................................36
8.2 Installation .....................................................................................................................................36
8.3 Potential equalization ....................................................................................................................36
8.4 Start-up .........................................................................................................................................36
8.5 Operation ......................................................................................................................................37
8.5.1 Degassing of the pumped medium ............................................................................................37
8.5.2 Temperature indications .............................................................................................................37
8.6 Maintenance..................................................................................................................................37
9. Start-Up ......................................................................................................................................................38
9.1 Driving Motor.................................................................................................................................38
9.2 Initial start / Restart .......................................................................................................................38
10. Operation..................................................................................................................................................39
10.1 General .......................................................................................................................................39
10.2 Setting the delivery rate ..............................................................................................................39
11. Maintenance.............................................................................................................................................40
11.1 Working materials........................................................................................................................41
11.2 Drive unit .....................................................................................................................................42
11.2.1 Drive motor ...............................................................................................................................42
11.2.2 Oil change ................................................................................................................................42
11.3 Dosing unit................................................................................................................................... 43
11.3.1 Overview of the tightening torques ...........................................................................................43
11.3.2 Changing the Diaphragm.......................................................................................................... 44
12. Spare and wearing parts ........................................................................................................................51
12.1 Wearing parts..............................................................................................................................51
12.2 Spare parts..................................................................................................................................51
12.3 List of spare and wearing parts ...................................................................................................52
13. Fault analysis and corrective action......................................................................................................54
14. Shut-down................................................................................................................................................56
15. Disposal....................................................................................................................................................56
15.1 Dismantling and transport ...........................................................................................................56
15.2 Complete disposal.......................................................................................................................56
16. Clearance Certicate...............................................................................................................................57
17. Appendix ..................................................................................................................................................59

4Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
Before commissioning and during operation of the sera dosing pump the respective regulations valid at the place of
installation are to be observed.
The sera dosing pump is delivered ready for installation. Carefully read these instructions and especially the safety
instructions herein contained before installation and initial start-up of the pump.
1. General
1.1 General user information
1.2 Symbols and notes used in these operating instructions
Special notes in these operating instructions are marked with text and danger symbols.
Designation of the note Danger type Denition of the note
(Text and symbol)
Danger of fatal injury Risk of injury Damage to property
(in the operating instructions)
DANGER! XXX
Identies an imminent danger
that results in fatal or severe injuries if not
avoided.
WARNING! XXX
Designates a potentially dangerous situation
There might be danger to life or serious injury and
damage to property if it is not avoided.
CAUTION! X X
Designates a potentially dangerous situation
There might be slight or minor injury or damage to
property if it is not avoided.
ATTENTION! X
Designates a potentially dangerous situation
that could lead to damage to property if not
avoided.
NOTE! Designates information which helps to make work
easier and is useful for trouble-free operation.
1.3 Notes attached to the product
Symbols which are directly attached to the pump, e.g. arrows for direction of rotation or symbols for uid connections
are to be observed and kept in legible condition.

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TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
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2. Safety instructions
1.4 Quality instructions
2.1 Personnel qualication and training
2.2 Dangers in case of inobservance of the safety instructions
Observance of these operating instructions and, in particular, the safety instructions, helps to
■avoid dangers to persons, machines and environment.
■increase reliability and service life of the product and the complete system.
■reduce repair cost and downtime.
The sera quality management and quality assurance system for pumps, systems, valves and ttings and compres-
sors is certied according to ISO 9001:2008.
The sera product meets the valid safety and accident prevention regulations.
Always keep these operating instructions within reach at the place of installation.
ATTENTION!
Pay attention to the safety data sheet of the medium! The owner must take cor-
responding accident prevention measures to protect operating personnel from
danger through the delivery media used!
WARNING!
The personnel for operation, maintenance, inspection and installation must be suitably qualied for their tasks. The
owner must clearly dene responsibility and supervision of the personnel.
If the personnel do not have the knowledge required, then personnel is to be trained and instructed correspondingly.
Such training can be provided by the manufacturer / supplier upon order of the owner. In addition, the owner has to
ensure that personnel have understood the operating instructions completely.
Inobservance of these safety instructions can result in danger to persons, hazards to the environment and damage
to the product.
Inobservance of the safety instructions may lead to:
■Failure of important functions of the product/system.
■Inobservance of prescribed methods for maintenance and servicing.
■Danger to persons through electrical, mechanical and chemical inuences.
■Hazards to the environment through leaking dangerous media.
2.3 Safety conscious working
The safety instructions specied in this operating manual, the national regulations for accident prevention, the safety
regulations for the pumped medium valid at the place of installation as well as internal working-, operating-, and safety
instructions of the owner are to be observed.

6Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
2.5 Safety instructions for maintenance, servicing and installation work
2.6 Arbitrary modication and production of spare parts
2.8 Intended use
The owner must ensure that any maintenance-, servicing- and installation work is only entrusted to authorized and
suitably qualied personnel who have carefully read and understood the operating instructions.
Only those spare parts and operating supplies are to be used which meet the requirements of the specied opera-
ting conditions.
Threaded joints and connections may only be disconnected when the system is not under pressure.
Modications of or changements to the pump are only permitted after previous agreement of the manufacturer. Origi-
nal spare parts and accessories which were approved by the manufacturer are essential for safety reasons.
If the pumps (e.g. drive motor) are modied without au-thorization of the manufac-
turer or spare parts are used which are not approved, any warranty claim becomes
null and void.
CAUTION!
The sera product is only to be deployed according to the intended purpose stated in the product description and the
acceptance test certicate.
If the product is to be used for other applications, then the suitability of the product for the new operating conditions
must be discussed with sera beforehand!
Criteria for operation in accordance with the intended use:
■Observe characteristics of the medium (please see safety- and product data sheet of the delivery
medium – the safety data sheet is to be provided by the supplier / owner of the medium).
■Resistance of the materials which come into contact with the medium.
■Operating conditions at the place of installation.
■Pressure and temperature of the medium.
■Voltage supply.
2.7 Improper operations
Operating safety of the supplied product is only guaranteed if the product is used as intended, according to the
descriptions in Chapter 2.8 of these operating instructions.
2.4 Safety instructions for owner / operator
Leaking hazardous delivery media and operating supplies are to be disposed off in such a way that any danger to
persons and the environment is excluded. The legal regulations are to be observed.
Danger caused by electrical energy is to be avoided.

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TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
2.10 Personal protection for maintenance and service
The provisions of the German Ordinance on Hazardous Substances (GefStoffV) (§14 Safety Data Shee) and relevant
national safety regulations for the pumped medium must strictly be adhered to.
In case of accidents check whether the following substances are emitted:
■Leaking uids.
■Leaking vapours.
■Noise emissions (sound level).
Emissions are to be monitored by corresponding controly systems of the total installation.
Wear protective clothing, gloves, breathing mask and a face protecting mask.
ATTENTION!
Personal protective equipment must be provided by the owner!
NOTE!
NOTE!
If not agreed otherwise in the contract conditions, the sera dosing pump will always be supplied with the necessary
utilities. (For type and quantitiy of utilities/lubricants, see Chapter 11.1 „Working materials“).
2.11 Utilities/Lubricants
2.9 Operating conditions
■Ambient temperature: 0°C to 40°C
■Climate: relative air humidity < 50%
■Installation altitude: max 1000m above sea level
■Pump design data for dosing and its temperature can be found in the order conrmation.

8Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
■Power supply not fuse protected (no fuse/fuse too large, power supply not conforming to standards).
■No or improper fastening material of the pump.
■Improper connection of the pressure pipes, wrong material i.e. PTFE tape and unsuitable connection pieces.
■Liquid pipes confused.
■Threads overturned/damaged.
■Pipes bent during connection in order to compensate for alignment errors.
■Supply voltage connected without earthed conductor.
■Socket for safe disconnection of the power supply difcult to reach.
■Wrong connecting cables for supply voltage (cross-section too small, wrong insulation).
■Parts damaged (e.g. vent valve, ow meter broken off).
■Wrongly dimensioned pressure and suction pipe.
■Incorrect dimensioned and improperly fastened pump panel (panel broken off).
2.12.2 Assembly and installation
2.12 Foreseeable misuse
The following misuse is assigned to the life cycles of the machine.
Misuse can result in danger to the operating personnel!
DANGER!
■Tipping behavior during transport, loading and unloading ignored.
■Weight for lifting underestimated.
2.12.1 Transport
■Fault message ignored ► faulty dosing / process error.
■Pipes hit, pulsation damper not used ► damage to the pipes, medium is leaking.
■Pumped medium contains particles or is contaminated.
■External fuse bridged ► no cut off in case of an error.
■Ground wire removed ► no cut off by fuse in case of an error, supply voltage directly at the housing.
■Insufcient lighting of the working place.
■Suction height too high, pump capacity too low ► process error.
■Arbitrary modication of the pump (valves, internal fuse, …).
2.12.4 Operation
■Cover on vent openings (e.g. motor).
■Suction or pressure pipes closed (i.e. foreign matters, particle size, stop valves).
■Start-up with damaged system.
2.12.3 Start-up
■Wrong setting of the hydraulic compensating valve
■Setting of the hydraulic compensating valve misadjusted.

9
TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
■Works carried out which are not described in the operating instructions (works on the stroke mechanism and
the assembly pump, electronics opened).
■Prescribed maintenance schedules ignored.
■Use of wrong spare parts/oils (e.g. no sera original spare parts, wrong viscosity).
■Improper mounting of spare and wearing parts (e.g. wrong tightening torque for pump body).
■Oil level not checked.
■Use of cables with damaged insulation.
■No shut down / no protection against a restart before maintenance work.
■Pumped medium or utilities during an oil change insufciently removed.
■Restart without sufcient fastening.
■Valves confused.
■Sensor pipes confused.
■Pipes not connected (e.g. suction- and pressure pipes, gas pipes).
■Gaskets damaged, medium is leaking.
■Gaskets not tted, medium is leaking.
■Wearing of unsuitable protective clothing / no protective clothing at all.
■Operation of an uncleaned system.
■Pumped medium contaminated with oil.
■Poorly ventilated room.
2.12.5 Maintenance/Repair
■Wrong rinsing medium (material changed, reaction with the medium).
■Wrong cleaning agent (material changed, reaction with the medium).
■Cleaning agent remains in the system (material changed, reaction with the medium).
■Protective clothing insufcient or missing.
■Use of unsuitable cleaning utensils (material changed, mechanical damage by high pressure cleaner).
■Untrained personnel.
■Vent openings clogged.
■Parts torn off.
■Sensors damaged.
■Non-observance of the safety data sheet.
■Control elements actuated.
■Poorly ventilated room.
2.12.6 Cleaning
■Pumped medium not completely removed.
■Disassembly of pipes with the pump running/with residual pressure.
■Disconnection of the electrical connections in a wrong sequence (ground wire rst).
■Disconnection from the power supply not ensured ► danger through electricity.
■Poorly ventilated room.
2.12.7 Shut-down
■Residues of the pumped medium and utilities in the system.
■Use of wrong disassembly tools.
■Wrong or no protective clothing at all.
■Poorly ventilated room.
2.12.8 Disassembly
■Improper disposal of the pumped medium, utilities and materials.
■No marking of hazardous media.
2.12.9 Disposal

10 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
sera products are checked for perfect condition and function previous to shipment.
Check for transport damage immediately after arrival of goods. If damage is found, this is to be reported immediately
to the responsible carrier and the manufacturer.
The packaging material must be disposed of appropriately!
NOTE!
3. Transport and storage
3.1 General
An undamaged packaging protects the unit during storage and should only be opened when the product is installed.
Proper storage increases the service life of the product and includes prevention of negative inuences such as heat,
moisture, dust, chemicals etc.
The following storage specications are to be obsered:
■Storage place: cool, dry, dustfree and slightly ventilated
■Storage temperature between +2°C and +40°C
■Relative air humidity not more than 50 %.
■The maximum storage time for the standard system is 12 months.
If these values are exceeded, metal products should be sealed in foil and protected from condensation water with a
suitable desiccant.
Do not store solvents, fuels, lubricants, chemicals, acids, disinfectants and similar in the storage room.
3.3 Storage
3.2 Transport
Select a hoist which is adapted to the weight of the pump and at-
tach it to the motor ange of the pump.

11
TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
4. Product description
4.1 Types
4.1.1 Type key
Type of drive (combinations possible)
Ccontrollable
Sself ventilating
Mnot adjustable
Rgenerally adjustable
FMotor suitable for frequency converter operation
iFrequency converter, mounted on the motor
PPole-changing motor
KStroke mechanism with side drive shaft and connected to the drive via a clutch
Ztwin design
XStroke mechanism with two opposite pump heads, combined suction and pressure side
YStroke mechanism with two opposite pump heads
Series
204 (solenoid driven pumps)
409 (motor driven pumps)
410 (motor driven pumps)
411 (motor driven pumps)
509 (motor driven pumps)
510 (motor driven pumps)
511 (motor driven pumps)
Revision index
max. Nominal capacity (litre/hour (each pump head))
Displacer (type of construction)
(without) Double diaphragm
eSingle diap hragm
ML Multy-layer diaphragm
12345
KM Piston Diaphragm
R 409 .2-70 KM (Example)

12 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
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4.1.2 Type plate
Each sera dosing pump is factory provided with a type plate.
The following information can be found on this type plate.
4.2 Materials
The materials used are stated in the order conrmation and the product description.
4.3 Viscosity, pumped medium
The diaphragm pump is suitable for uids with viscosities < 100 mPas.
4.4 Dosing range
The delivery rate of the diaphragm pump can be set manually via the stroke length adjustment (0…100%).
The linear dosing range is between 20% and 100%.
4.5 Noise measurement
According to DIN 45635 the sound pressure level measured of the diaphragm pumps is between 50 and 65 dB (A).
Type
No.
P
1
min/max
P
2
max
bar
bar
nN
Hydrfl
QNl/h
1/min
cm
3
1
2
3
4 5
7
6
No. Designation
1Pump type
2Serial number of the pump
3
Minimum/maximum permissible pressure in the pump inlet
Minimum/maximum permissible pressure in the inlet cross section which the pump can be used for.
Please consider that pressure depends on rotation speed, delivery rate, temperature and static pressure
at the inlet.
4
Maximum permissible pressure in the pump outlet
Maximum permissible pressure in the outlet cross section which the pump can be used for. Please consi-
der that pressure depends on rotation speed, delivery rate, temperature and static pressure at the outlet.
5Buffer uid
Quantity of buffer uid in the diaphragm ring (in the case of double diaphragm pumps).
6Nominal stroke frequency
7
Nominal delivery rate
Delivery rate which the pump was ordered for, based on the nominal rotation speed nN, the nominal deli-
very height p2max. and the delivery medium stated in the supply contract.

13
TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
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4.6 Assembly groups of the piston diaphragm pump
No. Designation Remark
1Attached frequency converter option
2Drive motor for frequency converter operation option
3Drive motor
4Blind plug (M-design)
5Manual stroke length adjustment
6Manual stroke length adjustment with position indicator option
7Stroke length adjustment with actuator option
8Stroke frequency transmitter (with inductive-contact) option
9Suction valve
10 Assembly pump
11 Pump body with diaphragm rupture signal
12 Pressure valve
not illustrated
Actuator for explosion-hazardous area option
EExeIIT4 - motor option
Diaphragm rupture electrode pressure switch option
1
2
3
4
5
7
9
8
6
11
12
10

14 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
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Piston diaphragm pumps consist of the following (main) components:
■Drive motor
■Stroke mechanism
■Stroke length adjustment
■Assembly pump
■Pump body
■Suction and Pressure valve
■Diaphragm rupture monitoring
4.7 Functional description
4.7.2 Stroke mechanism
Piston diaphragm pumps of this type series use a rotary cam
drive to transmit the rotation of the drive motor to the displace-
ment body.
In case of the rotary cam drive, the eccentric (2) provides the
pressure stroke while the suction stroke is performed by a pres-
sure spring (return spring) (3).
The effective stroke length can be changed by means of an
adjustable scale knob (1) which prevents the connecting rod
from following the rotary cam up to the rear dead centre during
suction stroke (see stroke length adjustment).
4.7.1 General
sera dosing pumps are run-dry safe oscillating displacement pumps that are characterised by high tightness of the
dosing head. The uid is conveyed by a deformable diaphragm.
4.7.3 Driving motor
sera - dosing pumps are driven either by a three-phase motor.
(Information about connecting the drive motor, see Chapter „Electrical connection / Interfaces“).
4.7.4 Stroke length adjustment
The delivery rate of the pump is set by changing the stroke length. The stroke length is innitely variable between
0% and 100%.
A linear dosing behaviour is achieved with stroke length adjustments between 20% and 100%.
3
1
2

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TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
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4.7.4.1 Manual stroke length adjustment (standard)
The effective stroke length of the connecting rod is changed
by turning the scale knob.
The stroke length should be adjusted during operation of
the pump.
The set stroke length can be read off a scale, e.g. 75% (see
Fig.).
With the 20-steps adjustment on the scale knob, the stroke
length can be set individually with a tolerance of 0.5%.
+ l/h- l/h
4.7.4.2 Manual stroke length adjustment by a dial scale with indication of
percent (option)
The stroke length is adjusted by turning the hand wheel.
The stroke length shuold be adjusted during operation of
the pump.
The set stroke length can be read off the percent scale (the
example shows a set stroke length of 65%).
In delivery state, the stroke length adjustment is factory set
to 50%.
+ l/h- l/h
The dial scale with indication of percent may become misadjusted during
transport.
If the indicator does not match the 50% setting, then the percent scale must
be re-adjusted during operation (!) of the pump!
ATTENTION!
Adjusting the percent scale:
■Switch on the piston diaphragm pump.
■Loosen setscrew (1).
■Remove percent scale (2) from the hand wheel (3).
■Manually turn the percent scale to 0% setting.
■Use the hand wheel to set the stroke length to 0%.
Turn hand wheel clockwise until there is no further stro-
ke movement (connecting rod does no longer hit the
adjusting spindle (4)).
■Insert percent scale again.
■Use the setscrew to secure the percent scale to the
hand wheel.
■Adjust desired stroke length.
3
2
4
1

16 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
4.7.4.4 Automatic stroke length adjustment by means of an electrical actua-
tor with integrated positioner (PMR3)
same as Chapter 4.7.4.3, additionally:
■PMR3 positioner
This PMR3 positioner which is integrated in the actuator enables an actuator setting from 0…100% that is
proportional to the connected input signal.
As an option, the actuator can also be provided with a collective interference signal.
Information on the electrical connection is given inside the cover of the actuator.
4.7.4.3 Automatic stroke length adjustment by means of an electrical actua-
tor
The electrical actuator is directly mounted to the stroke me-
chanism (1) of the dosing pump. A clutch transmits the rota-
ry motion of the actuator drive shaft to the adjusting spindle.
The axial displacement is compensated in the clutch (2).
In case of dosing pumps with electrical actuator, a manual
adjustment of the stroke length on the pump is no longer
possible.
(Exception: actuator with hand wheel)
The actuator is equipped with two integrated limit switches
as well as a position potentiometer for position feedback as
standard.
Both limit switches are factory set so that the drive will
switch off at a stroke length of 0% and 100%, even if a con-
trol voltage is applied.
This guarantees that adjustments can only be made within
the permissible range. The position potentiometer is driven
by a safety clutch which prevents damage caused by incor-
rectly adjusted limit switches.
Activation is performed by appropriate control units
(see sera - accessories)
2
1
The set stroke length can be read off on the pump (percent scale)
Information on the electrical connection is given inside the cover of the actuator.
The adjustment is only possible when the pump is running.
ATTENTION!
4.7.4.5 Automatic stroke length adjustment by means of an electrical actua-
tor (Ex-design)
Pay attention to the documents attached to the actuator.

17
TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
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4.7.5 Assembly pump
The stroke movement of the mechanically linked piston (4) is
transferred hydromechanically to the intermediate diaphragm
and thus to the pumped medium (7).
The multi-layer diaphragm (6) touches the spherical cap (pump
body (8) or diaphragm ring) when the pressure stroke nishes
in the front dead centre.
The compensating valve (1) ensures an optimum quantity of
hydraulic uid (5) between diaphragm and piston.
The so-called blow valve (2) and the hydraulic discharge val-
ve (3) are the most important components of the compensa-
ting valve. Both valves are spring-loaded and can be adjusted
according to the operating conditions (see Chapter „Setting the
compensating valve“).
Minimum quantities of uid may leak on the piston which are
compensated for by the adjustable blow valve at each suction
stroke.
The leaking uids are returned to the store tank (9) via a return
pipe (10).
During the operation the pump`s
hydraulic uid may change the
color. This will not affect the life
time respectively the safety of
the pump.
NOTE!
Thus, the system is closed and no more hydraulic uid may
leak out; during normal operation there is no need to replenish
hydraulic uid.
The blow valve always sucks in a greater quantity of hydraulic
uid than is leaking out at the piston during each suction stroke.
The excess quantity is returned into the store tank via the hy-
draulic discharge valve at the end of a pressure stroke when
the diaphragm touches the calotte.
If a stop valve is closed in the pressure pipe during operation
of the pump, the complete stroke volume of hydraulic uid is
returned into the store tank to protect the pump from overload.
The hydraulic discharge valve
protect the pump, not the sys-
tem!
ATTENTION!
If the pressure in the pressure pipe falls below the set pressure
of the hydraulic discharge valve, the blow valve sucks in hy-
draulic uid until the optimum volume has been reached.
This process can take up to several minutes, depending on the
operating conditions.
The open system of the hydraulic discharge valve starts at the
set pressure.
1
3
2
4
5
6
7
8
With a blocked pressure line can the piston diaphragm pump generate the counterpressure, which can lie up to a
certain value about the set pressure of the hydraulic discharge valve. The height of the achievable possible coun-
terpressure over the set pressure is dependent on the respective pump design.
Blow- and hydraulic discharge valve are set to the pressure specied in the order conrmation before shipment.
9
10

18 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
2
1
3
4.7.6 Pump body
4.7.5.1 Multi-layer Diaphragm
The multi-layer diaphragm consists of a package
of a total of three individual diaphragms:
■Working diaphragm (medium-contacted) (1)
■Signal diaphragm (slotted) (2)
■Protection diaphragm (with notch) (3)
The notch (4) of the protection diaphragm indicates the
correct mounting position changing the diaphragm set (see
Chapter „Replacing the diaphragm“).
The direction of the notch (4)
does not matter.
NOTE!
1
4
3
2
The hydraulic discharge valve is not a safety valve according to the pressure
equipment directive 97/23EC.
NOTE!
The diaphragm rupture signalization is integrated in the pump body (see g. „Diaphragm rupture monitoring“).
Depending on the applied backpressure, movements of the plastic pump body in elastic materials are possible.
This does not affect the pumps’s service life or operational reliability.

19
TA 435 Rev. 11 en 03/2016 Subject to technical modications!
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
4.7.7 Suction-/Pressure valve
The pump valves are ball valves that only work properly in a
vertical position. The condition of the valves has a deciding ef-
fect on the operating capability of the pump.
Valves must be exchanged as complete units.
When replacing the valves it is important to check the ow di-
rection (1).
Pressure valve above; Suction
valve below!
ATTENTION!
4.7.8 Stroke frequency transmitter (option)
Technical data Wiring diagram
Rated voltage: 10 - 60 V DC
+
-
1 BN
4
schwarz
3 BU
V
10 - 60 V DC
BK
Constant cur-
rent:
< 200 mA
short circuit-proof
Connection
mode: plug connector with 2 m cable
LED (green): indicates supply voltage
LED (yellow): indicates switching status
When switching inductive loads (protectors, relays, etc.), surge protectors (va-
ristors) must be tted owing to the high self-induction voltage.
ATTENTION!
When the pump is deployed in exlosion-hazardous areas a NAMUR type stoke
frequency transmitter (II2G EExia IICT6, gem. ATEX95) is to be provided.
WARNING!
sera dosing pumps are oscillating displacement pumps with an
exactly dened stroke volume per each pump stroke.
If these dosing pumps should be used for automatic lling pro-
cesses or charge dosing, then the single pump strokes must be
determined and converted into electrical signals.
For this purpose, a stroke frequency transmitter (inductive
contactor (1)) is added to the pump (the option cannot mounted
additionally) and reports each single pump stroke to the eva-
luation unit (e.g. preselection counter, SPC-control unit, etc.).
1
1

20 Subject to technical modications! TA 435 Rev. 11 en 03/2016
Piston diaphragm pump
409.2
Operating instructions
www.sera-web.com
4.7.9 Diaphragm rupture monitoring
sera diaphragm pumps are equipped with a diaphragm rupture monitoring.
4.7.9.1 Visual diaphragm rupture monitoring by manometer (only local si-
gnalling)
Standard execution
In case of a rupture of the working diaphragm, the medium under pressure
ows through a bore in the pump body to the signalling manometer and
causes a pointer deection.
■Switch off the pump immediately.
■Replace the diaphragm.
■Clean the diaphragm rupture monitoring.
If the pump is operated with a backpres-
sure that is only slightly higher than the
permissible minimum pressure of p2=1bar,
then the deection of the pointer on the
manometer will also be slight!
NOTE!
During normal operation with intact membrane, the
manometer shows 0bar.
4.7.9.2 Diaphragm rupture monitoring by pressure switch
In case of a rupture of the working diaphragm, a pressure is generated
on the pressure switch. The present signal must be evaluated and further
processed in such a way that the pump is switched off instantly.