Endress+Hauser Cleanfit P CPA471 User manual

BA00217C/07/EN/13.12
71161810
Operating Instructions
Cleanfit P CPA471
Retractable process assembly

Cleanfit CPA471
Endress+Hauser 3
Table of contents
1 Safety instructions . . . . . . . . . . . . . . . . 4
1.1 Designated use . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Installation, commissioning and operation . . . . . . . . 4
1.3 Operational safety . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Notes on safety icons and symbols . . . . . . . . . . . . . . 5
2 Identification . . . . . . . . . . . . . . . . . . . . 6
2.1 Nameplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Order code and device version . . . . . . . . . . . . . . . . . 6
2.3 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Installation . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Incoming acceptance, transport, storage . . . . . . . . . . 7
3.2 Installation conditions . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Installation instructions . . . . . . . . . . . . . . . . . . . . . 12
3.4 Sensor installation . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.5 Post-installation check . . . . . . . . . . . . . . . . . . . . . . 18
4 Operation . . . . . . . . . . . . . . . . . . . . . . 19
4.1 First commissioning . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Operating elements . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3 Manual operation . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.4 Pneumatic operation . . . . . . . . . . . . . . . . . . . . . . . 20
5 Maintenance. . . . . . . . . . . . . . . . . . . . 21
5.1 Cleaning the assembly . . . . . . . . . . . . . . . . . . . . . . 21
5.2 Cleaning the sensor . . . . . . . . . . . . . . . . . . . . . . . . 21
5.3 Cleaning agents . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.4 Replacing seals . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6 Accessories. . . . . . . . . . . . . . . . . . . . . 25
6.1 Installation accessories . . . . . . . . . . . . . . . . . . . . . . 25
6.2 Limit position switches . . . . . . . . . . . . . . . . . . . . . 26
6.3 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7 Trouble-shooting . . . . . . . . . . . . . . . . 28
7.1 Replacing damaged parts . . . . . . . . . . . . . . . . . . . . 28
7.2 Spare part kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.3 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.4 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
8 Technical data . . . . . . . . . . . . . . . . . . 33
8.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.2 Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.3 Mechanical construction . . . . . . . . . . . . . . . . . . . . 34
Index . . . . . . . . . . . . . . . . . . . . . . . . . 35

Safety instructions Cleanfit CPA471
4Endress+Hauser
1 Safety instructions
1.1 Designated use
The manually or pneumatically operated retractable assembly Cleanfit P CPA471 is designed for
installing pH/ORP sensors in tanks and pipes.
Its mechanical design permits its use in pressurized systems (see "Technical data").
Any other use than the one described here compromises the safety of persons and the entire
measuring system and is not permitted.
The manufacturer is not liable for damage caused by improper or non-designated use.
1.2 Installation, commissioning and operation
Please note the following items:
• Installation, commissioning, operation and maintenance of the measuring system must only be
carried out by trained technical personnel.
Trained personnel must be authorized for the specified activities by the system operator.
• Electrical connection must only be carried out by a certified electrician.
• Technical personnel must have read and understood these Operating Instructions and must
adhere to them.
• Before commissioning the entire measuring point, check all the connections. Ensure that
electrical cables and hose connections are not damaged.
• Do not operate damaged products and secure them against unintentional commissioning.
Mark the damaged product as being defective.
• Measuring point faults may only be rectified by authorized and specially trained personnel.
• If faults can not be rectified, the products must be taken out of service and secured against
unintentional commissioning.
• Repairs not described in these Operating Instructions may only be carried out at the
manufacturer’s or by the service organization.
1.3 Operational safety
The assembly has been designed and tested in accordance with the latest industry standards and left
the factory in perfect functioning order.
Relevant regulations and standards have been met.
As the user, you are responsible for complying with the following safety conditions:
• Installation instructions
• Local prevailing standards and regulations.

Cleanfit CPA471 Safety instructions
Endress+Hauser 5
1.4 Notes on safety icons and symbols
The structure, signal words and safety colors of the signs comply with the specifications of
ANSI Z535.6 ("Product safety information in product manuals, instructions and other collateral
materials").
Safety message structure Meaning
DANGER
!
Cause (/consequences)
Consequences if safety message
is not heeded
• Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid the situation will result in a fatal or serious
injury.
WARNING
!
Cause (/consequences)
Consequences if safety message
is not heeded
• Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid the situation can result in a fatal or serious
injury.
CAUTION
!
Cause (/consequences)
Consequences if safety message
is not heeded
• Corrective action
This symbol alerts you to a dangerous situation.
Failure to avoid this situation can result in minor or medium
injury.
NOTICE
Cause/situation
Consequences if safety message
is not heeded
• Action/note
This symbol alerts you to situations that can result in damage to
property and equipment.

Identification Cleanfit CPA471
6Endress+Hauser
2 Identification
2.1 Nameplate
The nameplate contains the following information:
• Manufacturer data
•Ordercode
• Extended order code
• Serial number
• Operating conditions
• Safety icons
Compare the order code on the nameplate with your order.
2.2 Order code and device version
Enter the following address in your browser to access the product page:
www.products.endress.com/cpa471
1. You can choose from the following options on the product page located on the right:
2. Click "Configure this product".
3. The configurator opens in a separate window. You can now configure your device and receive
the complete order code that applies for the device.
4. Afterwards, export the order code as a PDF or Excel file. To do so, click the appropriate button
at the top of the page.
2.3 Scope of delivery
The scope of delivery comprises:
• Cleanfit assembly (ordered version)
• Operating Instructions (English)
If you have any questions, please contact your supplier or your local sales center.

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Endress+Hauser 7
3 Installation
3.1 Incoming acceptance, transport, storage
• Make sure the packaging is undamaged!
• Inform the supplier about any damage to the packaging.
Keep the damaged packaging until the matter has been settled.
• Make sure the contents are undamaged!
• Inform the supplier about damage to the contents. Keep the damaged products until the matter
has been settled.
• Check that the order is complete and agrees with your shipping documents.
• The packaging material used to store or to transport the product must provide shock protection
and humidity protection. The original packaging offers the best protection. Also, keep to the
approved ambient conditions (see "Technical data").
• If you have any questions, please contact your supplier or your local sales center.
3.2 Installation conditions
3.2.1 Notes on installation
The assembly is designed for installation on tanks and pipes. Suitable nozzles must be available for
this.
When using standard glass sensors, only installation positions are permitted in which the
middle axis of the assembly lies at an angle greater than 15° from the horizontal (→å1).
Otherwise, there will not be a reliable contact between the inner side of the pH membrane and
the inner terminal leads via the electrolytes. Limited permissible angle of the installation
position is above 75° from the horizontal, air bubbles can accumulate in the chamber.
When using an ISFET Tophit sensor, there are, in principle, no restrictions for the installation
position. An installation angle of 0 to 75° is, however, recommended. An overhead installation
is possible.
a0008528
Fig. 1: Installation angles for glass sensors (X) and ISFET sensors (Y)
A Inadmissible installation angle
B Limited permissible angle (air bubbles can build up in the chamber)
C Recommended installation angle
90° 75°
15°
0°
0°
15°
75°
A
A
BC
C
90° 75°
0°
0°
75°
B
C
C
XY

Installation Cleanfit CPA471
8Endress+Hauser
a0007565
Fig. 2: Installation examples with recommended installation angle (glass electrodes)
ATank
BPipebend
CHorizontalpipe
D Ascending pipe
NOTICE
Wrong connection affects process safety
• For all assemblies with stainless steel pressure cylinders, we recommend to use a flanged version
when installing with inclined orientation. Otherwise, the weight of the assembly could affect
the safety of the process connection.
• Avoid a siphon effect1) at the rinse chamber outlet when installing with inclined orientation. The
inlet to the rinse chamber must be from below.
The minimum diameter for direct installation in pipework is DN 80. This diameter is required
so that the assembly has sufficient distance from the pipe wall when brought into the
"Measuring" position.
Use a flow assembly to install the assembly in smaller pipe diameters (see Accessories).
When designing the installation nozzle, please observe the total immersion depth in operation
(sensor holder not inserted). Ensure that the sensor is always immersed in the medium during
operation (see "Dimensions").
>15°
>15°
>15°
>15°
AB
CD
1) Siphon effect: line emptied by vacuum

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3.2.2 Dimensions
a0008304
Fig. 3: Long version for gel sensors
*Stroke
a0008306
Fig. 4: Short version for KCl sensors
*Stroke
80 (3.15)
67 (2.64)*
295 (11.6)
438 (17.2)
95 (3.74)
40
(1.57)
Ø 24.8 (0.98)
Ø 18 (0.71)
mm (inch)

Installation Cleanfit CPA471
10 Endress+Hauser
The short version with flange DN 50 is suitable for compact block flanges only. Flanges with
nozzle require the long version.
Use liquid KCl electrodes with the short version only!
3.2.3 Process connections
a0008305
Fig. 6: Process connections (short version)
A G1¼ internal thread with union nut
B DN 50 dairy fitting
C NPT 1" external thread
D Triclamp 2"
a0008307
Fig. 5: Short version for gel sensors
*Stroke

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a0008303
Fig. 7: Process connections (long version)
A DN 50 flange
B G1¼ internal thread with union nut
C DN 50 dairy fitting
D NPT 1" external thread
E Triclamp 2"
187 (7.36)
40
(1.57)
40
(1.57)
201 (7.91)
40
(1.57)
191.5 (7.54)
40
(1.57) 166 (6.54)
40
(1.57) 200 (7.87)
mm (inch)
ABC
DE

Installation Cleanfit CPA471
12 Endress+Hauser
3.3 Installation instructions
3.3.1 Measuring system
a0006077
Fig. 8: Measuring system with pneumatic control
1
2
3
4
5
6
7
8
pH/ORP sensor
Assembly Cleanfit
Transmitter Mycom CPM153
Special measuring cable
Communication / power supply cable
Power supply Mycom
Power supply CPG310
Control unit CPG310
9
10
11
12
13
14
15
Canisters for cleaning and buffer solutions
Superheated steam/water/cleaning solutions
(optional)
Rinse block
Rinse water valve
Power/signal cables
Air hoses
Media
123
8
9
10
11
13
14
15
MEAS CALCAL
DIAG PARAM
PARAM
?
45
6
7
12

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3.3.2 Installing the assembly into the process
WARNING
!
Risk of injury if medium escapes!
• Never insert the assembly into mesasuring position if no sensor is installed. Medium could leak
out.
Depending on the process connection, please observe the following:
Check the flange seal between the flanges before installing the assembly.
The thread adapter nut of thread G 1¼ does not function as a seal. Therefore, simply tighten
the thread adapter nut by hand.
1. Move the assembly into the "Service" position (electrode holder inserted in the assembly).
2. Secure the assembly to the tank or the piping using your selected process connection.
3. Follow the instructions for compressed air and rinse water connection (if used) given in the
following chapters.
3.3.3 Compressed air connection2)
Prerequisites:
• Air pressure from 4 to 6 bar (58 to 87 psi)
• The air must be filtered (40 μm), and free of oil and water
• No continuous air consumption
• Minimum nominal diameter of air ducts: 4 mm (0.16 ")
Connection thread: 2 x G 1/8
CAUTION
!
If the air pressure can exceed 6 bar or 87 psi (even transient pressure surges), the
assembly can leak, putting the user at risk of injury.
• Install a pressure-reducing valve upstream of the assembly.
• We recommend you also use a pneumatic throttle for lower pressures. This results in smoother
assembly operation. Such a throttle is available as an accessory (see "Accessories" section).
a0004479
Fig. 9: Operating elements
M =
S =
M1
M2
S1
S2
1
2
3
4
5
6
7
8
Measuring
Service
Pneumatics "Assembly measuring"
Limit position switch "Assembly measuring" 1)
Pneumatics "Assembly Service"
Limit position switch "Assembly Service" 1
(see chapter "Pneumatic operation")
Splash protection cap
Assembly housing (cylinder)
Seals in contact with medium
Retractable pipe
Potential matching
Stop bolt
Rinse fitting (optional)
Sensor holder (= sensor guide)
1) pneumatic or electric limit position switch depending on assembly version (see product structure)
2) pneumatically operated assembly only
1
M1
2
S1
3
4
5
S2
6
M2
7
8

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Limit position switches
The position of the input resp. the output may be different from the figure. Please, refer to the
marks at the limit position switch: "1" is the input (in), "2" is the output (out).
Pneumatics and limit position switch connection
Following, you find the connection of the compressed air lines to the assembly. The compressed air
supply and the tapping of the position feedback signals are described for Topcal S CPC310 resp.
Topclean S CPC30 as an example.
a0004480
Fig. 11: Pneumatic connections and pneumatic limit position switches (1=inlet, 2=outlet)
M1 Pneumatics "Assembly measuring"
M2 Position feedback signal "Assembly measuring"
S1 Pneumatics "Assembly service"
S2 Position feedback signal "Assembly service"
nTopcal/Topclean: hose no. 2
oTopcal/Topclean: hose no. 3
qTopcal/Topclean: hose no. 5
rTopcal/Topclean: hose no. 6
The pneumatic limit position switches serve as control elements and determine the sequence of the
individual steps.
1. Connect the compressed air supply line for "Assembly measuring" (Topcal/Topclean: hose
no. n) to the upper G 1/8 pneumatics connection (Fig. 11).
2. Also, connect the compressed air supply line no. nto the inlet (1) of the lower limit position
switch (M2, via T-piece). This limit position switch supplies the position feedback signal
"Assembly measuring".
Pneumatic: 3/2 way valve; thread M 12 x 1;
connection for hoses with OD = 6 mm (0.24")
Electric: inductive (NAMUR type); cable length: 10 m (32.8 ft);
housing material: stainless steel; thread M 12 x 1;
nominal voltage: 8 V
0II 1G EEx ia IIC T6; switching distance: 2 mm, flush
a0002727
Fig. 10: Limit position switches, left: pneumatic (1 = compressed air inlet, 2 = compressed air outlet)
right: electric (NAMUR)
out (2)out (2)
in (1)
in (1)
1/BN L+Õ
2/BU L–Õ
1
2
1
2
M1
S1
S2
M2
2
3
Topcal /
Topclean
Topcal /
Topclean
6
5

Cleanfit CPA471 Installation
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3. When the "Measuring" position is reached, the air applied to the inlet M2 (1) is switched
through and can be tapped at the outlet M2 (2) (Topcal/ Topclean: connect hose qto the limit
position switch outlet).
4. Connect the compressed air supply line for "Assembly service" (Topcal/Topclean: hose no. o)
to the lower G 1/8 pneumatics connection.
5. Also, connect the compressed air supply line no. oto the inlet (1) of the upper limit position
switch (S2, via T-piece). This limit position switch supplies the position feedback signal
"Assembly service".
6. When the position "Service" is reached, the air applied to the inlet S2 (1) is switched through
and can be tapped at the outlet S2 (2) (Topcal/ Topclean: hose no. r).
Electric limit position switch connection
Like the pneumatic limit position switches, the electric limit position switches also serve as control
elements and determine the sequence of the individual steps.
Connect the NAMUR limit position switches to the corresponding terminals at the transmitter.
Please, refer to the Operating Instructions of the transmitter for the terminal numbers. The following
figure shows the electric limit position switch connection to the terminals 11 to 14 of the Topcal S
control unit, as an example.
3.3.4 Rinse water connection
1. Connect the rinse water pipe to the designated rinse nozzle. Both rinse nozzles on the
assembly are identical. Use one as an inlet and the other as an outlet.
2. Operate the rinse water connection of the assembly with a water pressure of 2 to max. 6 bar
(29 to 87 psi).
3. In addition, install a non-return valve and a dirt trap (100 μm) in the water supply line (at the
inlet to the assembly).
Besides water, other or additional cleaning solutions may be used in the rinse chamber. Pay
attention to the material resistance of the assembly and comply with the maximum permitted
temperatures and pressures.
NOTICE
Water pressure too high
The assembly could be damaged.
• If it is possible for the water pressure to rise above 6 bar (87 psi, including any transient pressure
surges), install a pressure reducing valve upstream. Otherwise the assembly may be damaged.
a0004334
Abb. 12: Electric limit position switches to Topcal
A
B
Limit position switch "Assembly service"
Limit position switch "Assembly measuring"
+
+
11 12 13 14 A
B
–
–

Installation Cleanfit CPA471
16 Endress+Hauser
3.4 Sensor installation
3.4.1 Preparing sensor and assembly
NOTICE
Malfunction due to counter clockwise rotation
• If turned in the opposite direction, the stop lock bolt does engage, too. This could, however,
loosen the sensor holder. The reason for this are adhesions on the lower part of the sensor
holder. These can cause the sensor holder to get stuck, producing a counterforce when
unscrewing the sensor holder.
1. Remove the protection cap from the sensor.
Make sure the sensor shaft is fitted with the
O-ring and the thrust collar (→å13).
2. Moisten the sensor shaft before installing the
sensor.
3. Depending on the assembly version:
a. Manually driven assembly:
Pull the retractable pipe as far as possible
out of the assembly.
b. Pneumatically driven assembly:
Move the assembly into the "Service"
position.
4. Turn the stop lock bolt through 90° so that
the plastic grooves are located above the
recesses (→å14, A).
5. Turn the retractable pipe clockwise until
the stop lock bolt engages (B).
6. Vent the rinse chamber.
a0006214
Fig. 13: Sensor installation
1 Thrust collar and O-ring
a0002738
Fig. 14: Stop bolt
1
AB

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3.4.2 Gel sensor installation
Remove the sensor in the reverse sequence of operations.
In case of symmetrical pH measurement, you must push the PML connector onto the PML
connection (PML = potential matching line, position 1). Please, read the Operating
Instructions of the transmitter.
1. Remove the splash protection cap
(→å15, pos. 5) from the assembly.
2. Then loosen the retractable pipe (pos. 2) by
turning it anticlockwise.
3. Install the sensor (pos. 7) instead of the
dummy plug (pos. 3):
– first screw by hand
– then tighten the sensor by approx. ¼ turn
using an open end wrench (AF 17).
4. Insert the measuring cable through the
retractable pipe (pos. 2):
– Fixed cable:
from the bottom through the retractable
pipe, from the sensor to the transmitter
– Plug-in head sensor:
from the top to the sensor head
5. Plug-in head sensor only:
Connect sensor and cable.
6. Screw the retractable pipe back onto the
pressure cylinder (clockwise, by hand).
7. Place the measuring cable in the splash
protection cap and place the cap on the
retractable pipe.
8. Unlock the stop lock bolt (pos. 4).
a0002740
Fig. 15: Sensor installation
1 PML connection
2 Retractable pipe
3 Dummy plug
4 Stop lock bolt
5 Splash protection cap
6 Measuring cable with cable plug
7 Sensor or electrode
1
2
3
4
6
5
7

Installation Cleanfit CPA471
18 Endress+Hauser
3.4.3 Sensor with liquid KCl electrolyte
3.5 Post-installation check
• After installation, check that all connections are firmly in position and leak-tight.
• Ensure that the hoses cannot be removed without force.
• Check all hoses for damage.
1. Verify that the assembly is in the service
position and the stop lock bolt is engaged.
2. Remove the splash protection cap
(→å16, pos. 6) and the KCl hood
(pos. 7).
From version 11/2010 on the
retractable pipe stays in the cylinder
head.
3. Screw in the sensor directly into the inner
thread of the retractable pipe:
– first screw by hand
– then tighten the sensor by approx. ¼ turn
using an open end wrench (AF 17).
4. Insert the measuring cable through the
protective tube and the KCl hood:
– Fixed cable:
from the sensor upwards to the
transmitter
– Sensor with plug-in head:
from the top through the KCl hood to the
sensor
– In case of symmetrical pH measurement,
you must push the PML connector onto
the PML connection (PML = potential
matching line, pos. 3).
5. Plug-in head sensor only:
Connect sensor and cable.
6. Connect the electrolyte supply tube (pos. 1)
to the electrolyte connection of the sensor.
7. Affix the supplied tubing support (pos. 9) to
the electrolyte supply tube directly above the
electrolyte connection.
8. Attach the KCl hood to the retractable pipe.
Guide the electrolyte supply tube through
the lateral slot of the hood.
9. Place the measuring cable in the splash
protection cap and place the cap on the KCl
hood.
10. Unlock the stop lock bolt (pos. 5).
Remove the sensor in the reverse sequence of
operations.
a0011720
Fig. 16: Liquid KCl electrolyte sensor installation
1 Liquid KCl supply tube
2 Dummy plug
3 PML connection
4 Retractable pipe
5 Stop lock bolt
6 Splash protection cap
7 KCl hood
8 Plug-in head cable
9 Tubing support
10 Sensor with liquid KCl connection
1
2
3
4
7
8
5
10
9
6

Cleanfit CPA471 Operation
Endress+Hauser 19
4Operation
4.1 First commissioning
Before the first commissioning, make sure of the following items:
• All seals are correctly seated (on the assembly and process connection).
• The sensor is correctly installed and connected.
• The water supply line is correctly connected to the rinse connections (if fitted).
• The limit position switches (according to assembly version) are correctly connected.
WARNING
!
Risk of injury if medium escapes!
• Make sure the connections are correctly fitted with either rinsing hoses or dummy plugs before
applying compressed air to the pneumatic assembly. Otherwise the assembly may not be put
into the process!
4.2 Operating elements
Use the stop lock bolt to lock or release the retractable pipe (→å17, →å18).
When using manually operated assemblies, the retractable pipe can be locked in both, the
"Measuring" position and the "Service" position. When using pneumatically operated assemblies,
this can only be done in the "Service" position.
Releasing the stop lock bolt:
1. Pull the bolt out.
2. Turn the bolt by 90° so that the plastic grooves rest on the metal edge.
Locking the stop lock bolt:
3. Turn the stop lock bolt through 90° so that the plastic grooves are located above the recesses.
4. When the retractable pipe is turned clockwise, the bolt engages.
a0002744
Fig. 17: Releasing the stop lock bolt
a0002745
Fig. 18: Locking the stop lock bolt
12
34

Operation Cleanfit CPA471
20 Endress+Hauser
4.3 Manual operation
Moving the assembly from the "Service" position to the "Measuring" position
1. Release the stop lock bolt catch.
2. Push the retractable pipe so that the sensor holder is inserted fully into the process.
3. Lock the sensor holder with the stop lock bolt. This prevents the retractable pipe from
returning inadvertently into the "Service" position.
WARNING
!
Uncontrolled movement of the retractable pipe
Risk of injury
• Always lock the sensor holder. Otherwise, the retractable pipe may exit uncontrolled as a result
of the process pressure and injure somebody.
Moving the assembly from the "Measuring" position to the "Service" position
1. Release the stop lock bolt catch.
2. Pull the retractable pipe out as far as possible ("Service" position).
3. Lock the sensor holder with the stop lock bolt.
4. Complete the necessary service tasks.
4.4 Pneumatic operation
Operation of the pneumatic version depends on the used control unit. Refer to the operating manual
of the control unit for instructions.
During maintenance work (e.g. installing and removing the sensor), always lock the assembly
in the "Service" position by the stop lock bolt.
During the automatic rinse process, do not lock the retractable pipe by the stop lock bolt.
Otherwise the assembly can no longer move automatically to the "Measuring" position.
If a maintenance switch is fitted on the transmitter, set it to "Maintenance" or "Service".
It is not possible to lock the assembly in the "Measuring" position. The pneumatic system
maintains the back pressure to the process pressure.