Vega VEGADIF 65 User manual

Operating instructions
Isolating diaphragm CSS
for VEGADIF 65
Document ID:
36134
Differential pressure
p

Contents
1For your safety
1.1Authorised personnel ........................ 3
1.2Appropriate use ............................ 3
1.3Warning about misuse ....................... 3
1.4General safety instructions . . . . . . . . . . . . . . . . . . . . 3
2Product description
2.1Configuration .............................. 4
2.2Principle of operation ........................ 4
3Planning instructions for isolating systems
3.1Influence of the components . . . . . . . . . . . . . . . . . . . 5
3.2Influence of temperature changes ............... 6
3.3Calculation of the temperature error. . . . . . . . . . . . . . 6
4Mounting
4.1Application conditions ........................ 8
4.2Instructions for handling . . . . . . . . . . . . . . . . . . . . . . 8
4.3Mounting instructions ........................ 9
5Maintenance and fault rectification
5.1Maintain.................................. 10
6Supplement
6.1Technical data ............................. 11
6.2Dimensions ............................... 12
2Isolating diaphragm CSS •for VEGADIF 65
1Contents
36134-EN-090604

1For your safety
1.1Authorised personnel
All operations described in this operating instructions manual must be
carried out only by trained specialist personnel authorised by the plant
operator.
During work on and with the device the required personal protective
equipment must always be worn.
1.2Appropriate use
The isolating diaphragm is a functional part of the differential pressure
transmitter VEGADIF 65.
You can find detailed information on the application range in chapter
"Product description".
Operational reliability is ensured only if the instrument is properly used
according to the specifications in the operating instructions manual as
well as possible supplementary instructions.
1.3Warning about misuse
Inappropriate or incorrect use of the instrument can give rise to
application-specific hazards,e.g.vessel overfill or damage to system
components through incorrect mounting or adjustment.
1.4General safety instructions
The safety information in the operating instructions manual of the
respective sensor must be noted.
Isolating diaphragm CSS •for VEGADIF 65 3
1For your safety
36134-EN-090604

2Product description
2.1Configuration
The scope of delivery encompasses:
lVEGADIF 65
lIsolating diaphragm CSS mounted on VEGADIF 65
lDocumentation
-this operating instructions manual
The isolating diaphragm CSS consists of the components:separating
diaphragm,process fitting as well as transmission line (capillaries).
The components are fully welded with each other and with the
associated differential pressure transmitter and represent a hermeti-
cally sealed system.
+ –
1
2
3
4
Fig.1:VEGADIF 65 with isolating diaphragm CSS
1VEGADIF 65
2Process fitting
3Transmission line (capillaries)
4Separating diaphragm
2.2Principle of operation
Isolating diaphragms should be used if a separation between medium
and pressure transmitter is necessary,particularly with:
lHigh product temperatures
lCorrosive products
lStrong vibrations at the measurement point
The process pressure acts hydraulically on the transmission liquid via
the separating diaphragm.This liquid transmits the process pressure
through the capillary line to the sensor element of the differential
pressure transmitter.
Scope of delivery
Components
Application area
Functional principle
4Isolating diaphragm CSS •for VEGADIF 65
2Product description
36134-EN-090604

3Planning instructions for isolating systems
3.1Influence of the components
The following properties of the separating diaphragm determine the
application area of the isolating diaphragm:
lDiameter
lResilience
lMaterial
The bigger the diaphragm diameter,the higher the resilience and the
lesser the temperature influence on the measuring result.Note:To
keep the temperature influence in reasonable limits,you should use an
isolating diaphragm with a nominal width ≥DN 80.
The resilience also depends on the diaphragm strength,the material
as well as a possible coating.
In the selection of filling oil,product and ambient temperature as well
as process pressure are of utmost importance.Also take note of
temperatures and pressures during setup and cleaning.
Another criteria is the compatibility of the filling oil to the requirements
of the medium.In the food processing industry,e.g., only filling oils that
are harmless to health are permitted,such as e.g.med.white oil.See
overview of filling oils in the following chart.
Filling oil Permissible
product temper-
atures
Permissible
product temper-
atures at
0.05 bar
abs
<p
<1bar
abs
Densi-
ty in g/
cm³
Vis-
cosity
in m
2
/
s•10
-6
Expan-
sion co-
efficient
1/K
Cor-
rective
factor
for TK
Application
area
Silicone oil
KN17
-40 …+180 °C(-
40 …+356 °F)
-40 …+80 °C(-
40 …+176 °F)
0.96
up to
25 °C
55
up to
25 °C
0.00104 1 Standard
silicone oil
KN2.2
-40 …+200 °C(-
40 …+392 °F)
-40 …+150 °C(-
40 …+302 °F)
0.96
up to
20 °C
55
up to
20 °C
0.00104 1 Standard
High tempera-
ture oil KN 3.1
-10 …+300 °C(-
14 …+572 °F)
-10 …+200 °C
(+14 …+392 °F)
1.07
up to
20 °C
39
up to
20 °C
0.0008 0.77 high temper-
atures
High tempera-
ture oil KN 3.2
-10 …+400 °C
(+14 …+752 °F)
-10 …+200 °C
(+14 …+392 °F)
1.07
up to
20 °C
39
up to
20 °C
0.0008 0.77 high temper-
atures
Halocarbon oil
KN21 (BAM
tested)
-40 …+150 °C(-
40 …+302 °F)
-40 …+80 °C(-
40 …+176 °F)
1.968
up to
20 °C
14
up to
20 °C
0.00086 0.83 For oxygen
and chlorine
applications
Separating diaphragm
Isolating diaphragm fill-
ing oil
Isolating diaphragm CSS •for VEGADIF 65 5
3Planning instructions for isolating systems
36134-EN-090604

Filling oil Permissible
product temper-
atures
Permissible
product temper-
atures at 0.05
bar
abs
<p<1
bar
abs
Densi-
ty in g/
cm³
Vis-
cosity
in m
2
/
s•10
-6
Expan-
sion co-
efficient
1/K
Cor-
rective
factor
for TK
Application
area
Med.white oil
KN92 (FDA
approved)
-15 …+260 °C
(+5…+500 °F)
-15 …+160 °C
(+5…+320 °F)
0.85
up to
20 °C
5.6
up to
40 °C
0.00065 0.63 suitable for
foodstuffs
The implemented filling oil also influences the TK
zero point
,the
permissible ambient temperature and the response time of an isolating
diaphragm.See also chapter "Influence of the temperature to the zero
point"and "Response time".
The differential pressure transmitter also influences the temperature
application range,the TK
zero point
and the response time of the isolating
system through the volume of its lateral flanges and its control volume.
1)
3.2Influence of temperature changes
The filling oil expands as the temperature increases.The additional
volume presses on the isolating diaphragm.The more rigid the
diaphragm,the more it counteracts a volume change.The additional
volume also adds to the process pressure on the measuring cell and
thus shifts the zero point.The respective temperature coefficient
"TK
Process
"is listed in chapter "Dimensions and weights".
3.3Calculation of the temperature error
With unilateral mounting of the isolating diaphragm,the total temper-
ature influence is composed of the following:
lInfluence of the process temperature on the isolating diaphragm
(TK
Process
[mbar/10K])
lCorrective factor with special materials (with Tantalum,Hastelloy:
1.5;with PTFE:1.8)
lCorrective factor for filling oil
lInfluence of the ambient temperature on the capillary (TK
Ambient
[mbar/10K])
lInfluence of the ambient temperature on the pressure transmitter
(thermal modification of zero signal and span)
The calibration temperature of the isolating system is 20 °C.For the
calculation,the temperature must be deducted from the respective
process or ambient temperature.
1)The control volume is the volume that must be shifted in order to utilise the
complete measuring range.
Differential pressure
transmitter
Isolating diaphragm,
unilateral
6Isolating diaphragm CSS •for VEGADIF 65
3Planning instructions for isolating systems
36134-EN-090604

The TK
Process
isolating diaphragm is listed in the charts in chapter
"Dimensions and weights".The corrective factor for the filling oil is
listed in chapter "Overview".The thermal change of zero signal and
span is specified in chapter "Technical data".The calculated
influencing factors must be summed geometrically.
lProcess temperature:100 °C
lFlange isolating diaphragm DN 80 PN 10-40 with extension 50 mm
lCapillary length:4m
lDiaphragm material.: Tantalum,correction factor 1.5
lAmbient temperature TU:40 °C
TK
Isolating diaphragm
=0.4mbar/10K
ΔT Process temperature-Reference temperature isolating diaphragm
=100 °C-20 °C=80 K
TK
Capillaries
=0.3mbar/(10K•1m)
ΔT Ambient temperature-Reference temperature capillaries =60 °C-
20 °C=40 K
Error calculation
Δp
Isolating diaphragm
=(0.4mbar/10K) • 80K=3.2mbar
Corrective factor diaphragm material =4.8mbar •1.5=7.2mbar
Δp
Capillaries
=(0.3mbar/10K•1m) • 40K•4m=4.8mbar
Δp
Total
=7.2mbar +4.8mbar =12 mbar
With unilateral mounting of the isolating diaphragm,the total temper-
ature influence is 12 mbar
Example for isolating di-
aphragm,unilateral
Isolating diaphragm CSS •for VEGADIF 65 7
3Planning instructions for isolating systems
36134-EN-090604

4Mounting
4.1Application conditions
Before mounting,setup and operation,take note that the isolating
system as well as the pressure transmitter were selected according to
measuring range,version and material.The load limits must be
maintained in order to guarantee accuracy and operational life span.
Caution:
In dangerous substances such as e.g.oxygen,acetylene,combustible
or toxic products as well as in refrigerating plants,compressors,etc.,
the pertinent instructions must be observed in addition to the general
regulations.
The differential pressure transmitter must be mounted in such a way
that the permissible ambient and product temperature limits,also
under consideration of the influence of convection and heat radiation,
are neither underrun nor exceeded.
When selecting the pressure transmitter,the pressure temperature
resistance of the fitting and flange components must be considered
through the selection of the material and pressure stage.The pressure
stage stated on the isolating diaphragm applies to ambient temper-
atures.In case of higher temperatures,the max.permissible pressure
must be taken from the standard indicated on the isolating diaphragm.
To keep the temperature influence as low as possible,configuration or
mounting must be carried out in such a way that the plus and minus
sides are symmetrical with respect to ambient temperatures.
4.2Instructions for handling
lThe instruments must be protected against soiling and strong
fluctuations of the ambient temperature
lLeave the measuring system in the packaging until mounting to
protect it against mechanical damages
lWhen removing the packaging and when mounting,take special
care to avoid damage and mechanical deformation of the
diaphragm
lDo not carry the pressure transmitter by holding the capillary line
lDo not bent the capillary lines.Kinks can cause leakage and lead
to an increase in response time
lNever loosen sealed screws on the isolating diaphragm or the
pressure transmitter
lDo not damage the isolating diaphragm:scratches on the isolating
diaphragm (e.g.from sharp subjects)are the main areas where
corrosion can occur
Suitability for process
conditions
Consideration of the
ambient temperature
8Isolating diaphragm CSS •for VEGADIF 65
4Mounting
36134-EN-090604

4.3Mounting instructions
lSuitable seals must be selected for sealing
lFor flange mounting,use a seal with a sufficiently large inner
diameter and place the seal centrically;contact with the diaphragm
will cause measurement deviations
lWhen using soft material or PTFE seals,take note of the
regulations of the seal manuffacturer,particularly with respect to
torque and settling cycles
lLay in vibration-free areas to avoid additional pressure fluctuations
lDo not lay close to heating or cooling lines
lInsulate in case of colder or warmer ambient temperatures
lBending radius of the capillaries ≥150 mm
Sealing
Laying the capillaries
Isolating diaphragm CSS •for VEGADIF 65 9
4Mounting
36134-EN-090604

5Maintenance and fault rectification
5.1Maintain
When used correctly,no special maintenance is required in normal
operation.
In some applications,product buildup on the separating diaphragm
can influence the measuring result.Depending on the application,take
precautions to ensure that heavy buildup,and especially a hardening
thereof,is avoided.
Caution:
Never clean the separating diaphragm mechanically,for example with
tools!This can damage the diaphragm and lead to oil leakage.
If necessary,clean the separating diaphragm with a soft brush and
suitable cleaning detergent.Make sure that the materials are resistant
to the cleaning process,see resistance list under "Services"on "www.
vega.com".The wide variety of applications of isolating diaphragms
makes special cleaning instructions necessary for each application.
Please ask the VEGA agency serving you.
Maintenance
Cleaning
10 Isolating diaphragm CSS •for VEGADIF 65
5Maintenance and fault rectification
36134-EN-090604