TC FLUID CONTROL

Instrumentation Division
Unit 49a Victoria Industrial Park
Victoria Road, Dartford, Kent, DA1 5AJ
Tel: +44 (0) 1322 622400
Fax: +44 (0) 1322 285660
E-mail: instruments@tc-fluidcontrol.com

INSTALLATION / OPERATION / MAINTENANCE INSTRUCTIONS

Magnetic Level Gauge
Under the requirements of the Pressure Equipment Directive (PED 97/23/EC), the Magnetic Level
Gauge can not be classified as a pressure safety device. This equipment can only be used for
liquid fluid measurement.
1: General
The TC Fluid Control Magnetic level gauge is
designed to give an uninterrupted and
immediate level indication of most liquids
including steam condensate and arduous
chemicals. A variety of accessories can be
factory or retrofitted including transmitters and
various switches with the appropriate approvals.
2: Principle of Operation
The magnetic level gauge is designed so that
the liquid being measured is enclosed within a
sealed chamber. A float fitted with a permanent
omni-directional magnet moves freely inside the
chamber and actuates the magnetic wafer within
the indicator which is fixed on the outside of the
chamber body. As the float raises or falls with
the liquid level, each wafer rotates 180 and so
presents a contrasting colour. The wafers above
the liquid level will show white, whereas the
wafers below will show red. The indicator then
presents a clearly defined liquid level within the
chamber. The wafers can resist accidental
disturbance such as vibration due to their edge
magnetisation and mutual attraction. Optional
red and green wafers are available for steam
applications.
WARNINGS:

The maximum operating conditions are

specified on the tag plate and must not be exceeded.

Exceeding these limits may lead to a failure of the chamber integrity and
possible harm to persons/property.

The material selection of the gauge system must be suitable/ resistant for
the media and environmental conditions.

Design parameters allow the gauge to be operated up to 450C. Measures

should be in place to avoid contact with this equipment.

It is the clients responsibility to fit an appropriate pressure relief safety

device within the system being monitored.

The gauge system must not be modified, as this will invalidate the
certification.

Ensure vent and drain plugs are sealed during service.

Any work carried out on this equipment must be covered by a permit to

work procedure.
Commissioning

Installation and commissioning of the magnetic level gauge should only be

carried out by qualified and experienced engineer/ personnel.

All cabling and electrical connections must be carried out in accordance

with the regulations and standards applicable in the country where the
equipment is installed and by qualified personnel.

It is recommended that isolation valves should be fitted between the

gauge and the vessel. The selection of the gasket joints and fittings
(bolting) to have the required corrosion resistance and rated accordingly.
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3: Installation of the gauge.

Before mounting the gauge into position, the following points should be taken into account.

Vessel connections on the vessel/tank must be vertically in line.

It is not recommended that connections are taken from inlet or discharge lines as excessive surging may occur within the
gauge.

Centre to centre dimensions between vessel connections on the tank and gauge must be within 1.5 mm of each other.

Ensure connecting pipe work is adequately supported to reduce additional stress due to gauge weight.
Fit the gauge to the vessel/tank using the appropriate rated fixtures and gaskets. Ensure that the gasket material is resistant to
the media and its vapour. Make sure that the vessel flange bolting is tightened to the required torque value.
Optional extras such as the transmitter and switches are normally factory fitted onto the chamber. Switches can be adjusted
accordingly.
4: Installation of float.
Up-pack the float from its protective case and proceed as follows:
It may be necessary to align the indicator wafers to represent their white face; this can be achieved by running a magnet along
the length of the indicator unit. If a float failure warning indication is fitted, the bottom three wafers will show red. (Refer to the
appropriate IOM sheets with regards to the setting up procedure required for the switches).

Remove the bottom flange from the chamber

Check that the float fits freely into the chamber. If bumper wires are fitted on the float, these can be pushed down to aid
clearance. If there is insufficient clearance, consult TC Fluid Control Ltd.

Check that the specific gravity (S.G.) etched on the float is suitable for the media in question.

Clean the float of any adhering steel particles and install the float with the cap marked TOP uppermost in the chamber.

Replace the bottom flange and gasket. Bolt flange accordingly to the required torque value.
Recommended Bolt Torque.
Chamber
size

Typical
Gasket

Glass fibre
NBR binder

Spiral wound
316/graphite

Glass fibre
NBR binder

Bolt size

5/8 UNC

Rating
150

300

600

101 Nm
75 lb.f.ft

101 Nm
75 lb.f.ft

101 Nm
75 lb.f.ft

1 UNC

UNC

126 Nm
93 lb.f.ft

900

1500

423 Nm
312 lb.f.ft

528 Nm
390 lb.f.ft

177 Nm
131 lb.f.ft

Notes.

Values are based on lubricated ASTM A193 Grade B7 bolts fitted with ASTM A194 Grade 2H nuts (co-efficient of friction
=0.12), and are the minimum torque required to ascertain a seal. Please note that the final torque required to seal the
gasket joint may vary greatly due to the effects of temperature, corrosion, level of lubrication and thread finish.

For alternative flanging, bolting and gasket configurations, consult TC Fluid Control Limited for advice.

Bolts should be progressively tightened in a star pattern to ensure even gasket loading. Load should be applied in either
50/100% or 25/50/75/100% of the target torque value, this will depend on the integrity required for the joint.

The information given in the above table should only be used as a guideline and is not mandatory.
5: Functional Testing of the Gauge.
Before bringing the magnetic level gauge into service, it is advisable to carry out a functional test especially when switches
and/or transmitter are fitted.

Ensure that the gauge system is isolated from the vessel.

Wire in any switches and/or transmitter as required following the correct electrical procedures.

The level within the gauge can be imitated by pouring water into the chamber via the top vent.

Make appropriate checks covering the performance of any ancillaries and indicator operation.

Open the drain/drain valve and allow the water to run out, thus simulating a falling level.

Check ancillaries and the indicator unit accordingly.

Close vent and drain.

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6: Bringing into service.

If there are no isolation valves fitted between the level gauge and vessel, then the gauge will automatically be brought into
service along with the vessel.
When isolation valve are fitted, the procedure are as follows;

Allow time for the gauge to reach the operating temperature.

Ensure vent and drain connections are shut off.

Slowly open the isolation valve fitted to the upper vessel connection.

Slowly open the isolation valve fitted to the lower vessel connection. This will allow the liquid level to rise in the gauge
chamber thereby rotating the wafers to indicate red.
The actual liquid level is shown by the red/white wafer interface.
7: Maintenance.
No maintenance is required other than periodic inspection to ensure that the gauge is free from foreign particles, sediment or
scale etc. Freedom of the float movement may be checked by momentarily opening the drain valve if fitted, (depending upon the
process, the isolation valve may have to be closed. Follow the procedure 6: Bringing into service). A drop in the indicated level
will demonstrate that the float is free.
A damaged or punctured float will sink and this would be indicated by the bottom three wafers changing. In this event the float
must be replaced.
8: Removal of the gauge.

Isolate the gauge from the source of pressure/media by closing the appropriate isolation valves.
Relieve the gauge of any internal pressure and fluid contents by opening the drain valve. Ensure all safety precautions are
in place for safe disposal of the contents. Time must be allowed for the gauge and contents to cool prior to this operation.
Warning: The pressurised level gauge may contain potential hazardous fluids. Wear appropriate protective clothing.
When the gauge has cooled, isolate and remove any ancillary equipment.
Dismantle respective vessel connections and remove the gauge.

9: Removal of the float.

Isolate the gauge from the source of pressure/media by closing the appropriate isolation valves.
Relieve the gauge of any internal pressure and fluid contents by opening the drain valve. Ensure all safety precautions are
in place for safe disposal of the contents. Time must be allowed for the gauge and contents to cool prior to this operation.
When the gauge has cooled, remove the bottom flange.
Remove the float.

10: Service Life.

Service life depends upon the combination of pressure/temperature and the media. A majority of the gauges are constructed
from stainless steel and should give a long service life due to concept of passive protection. The effects of chemical agents,
corrosion and vibration are covered by the requirements of the PED 97/23/EC. Alternative materials can be supplied for certain
arduous conditions. Check condition of the float and spring damper system (if fitted) periodically. Generally service life is 10
years unless otherwise specified.
11: High temperature Service.
For gauge operating above 150C or below 0C, insulation is fitted between the indicator unit and the gauge body. The level of
insulation is dependent upon the temperature. This must be re-fitted whenever the indicator is removed.
12: Spares.
All replacement components must be genuine TC Fluid Control Ltd. spares. When ordering, the TC Fluid Control job number
and tag number should be quoted. This information can be found on the nameplate, which is normally fitted to the bottom
flange.

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13:Gauge subjected to ATEX requirements

The magnetic level gauge is covered by EN
13463-1 for the use of non-electrical equipment
for potentially explosive atmospheres as defined
by EC directive 94/9/EC.

ITEM
1
10
25
26
27
28
29
30
31

DESCRIPTION
GAUGE BODY
FLOAT
S/S SPRING
PTFE CAP
RING
NON FROST BLOCK
S/S CLADDING
EARTH STUD
ATEX LABEL

14: Certification
Category 1
Category 1/2
Category 2

SIRA 04ATEX6126
SIRA 04ATEX6126
SIRA 04ATEXT133

15: Temperature class

Relationship between T rating Temperature class, Ambient and Process Temperatures.

Temperature Class

Process Temperature

T1
T2
T3
T4
T5
T6

[ 4508C
[ 3008C
[ 2008C
[ 1358C
[ 1008C
[ 858C

Ambient Temperature

-50 8C+80 8C

-50 8C+60 8C

The operating conditions must not exceed the maximum process temperature shown in the above table for a given T rating.
Conditions for safe use:

Stainless steel clad non-frost blocks must be earth bonded for category 1 and 2 applications.

Clean non-frost block vision panel only with a damp cloth.

Limit the maximum float velocity under surging conditions to 1 m/s by fixture the appropriate flow restrictions.

For any surging conditions (stainless steel or titanium floats), spring buffer with PTFE cap must be fitted to category I, II and
III applications.

Check periodically the condition of the float and spring assembly. Follow procedures as stated for the removal of the float.

Maximum process temperature for ATEX categories I, II and III applications when fitted with a spring damping system is
limited to 2608C (depending on media).

For process medias which are subjected to gassing off or surging due to temperature changes, it is recommended to fit
insulation around the gauge body.

No tools that may cause a spark to be used in a potentially explosive atmosphere unless covered by a Permit to Work
system.

For electrical equipment such as transmitters or switches, refer to the respective IOM.

Use stainless steel clad display units for category I applications.

Maximum process temperature for a stainless steel float is 450C and a titanium float is 315C
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TROUBLE SHOOTING GUIDE

Problem

Possible cause
Isolation valves closed.
Blockage in the connecting pipe-work.

Float fails to raise or fall

Float sticking in chamber.

Float damaged.
Incorrect S.G. float used.

The S.G. of the float differs to that of

the media.
Incorrect level is displayed.

Banks or clusters of wafers are not

turning.

Inverse wafer operation.

The float has been incorrectly

installed upside down
The media has surged thus causing
the float within the chamber to travel
at abnormally high speed thus
missing the magnetic field of the
wafers.
Damaged float magnet.
Indicator upside down.

Maximum temperature on the gauge

tag plate has been exceeded.
Wafers in
discoloured.

the

indicator

have
Heat shields have been removed and
not replaced

Action/ rectification procedure

Open slowly as appropriate as per
procedure 6.
Clean blockage as required
Remove the float as per procedure 9.
Check clearance between the bumper
wires and the chamber bore. If
insufficient clearance, push the
bumpers down flat to aid clearance.
Check that there is no sediment, scale
or solidification of the media built up
inside the chamber.
Check for puncture and ingress of
media into float.
Check that the S.G. range etched on
the float matches the corresponding
media S.G.
Check that the S.G. range etched on
the float matches the corresponding
media S.G.
Remove the float and replace with the
top end uppermost in the chamber.
Reduce surging by fitting orifice plates
or throttling the vessel valves
accordingly.

Replace with new float. Carry out

functional test as per procedure 5.
Check orientation of indicator. Note
that top is stamped on end cap of
indicator.
Heat shield/s are required.
If already fitted, then the insulation
specification needs to be increased.
Replace indicator if required.
Refit insulation between display and
chamber.
Replace indicator if required.

All information and recommendations contained in this publication are to the best of our knowledge correct. Since conditions of use are beyond our control, user
must satisfy themselves that the product is suitable for the intended processes and uses. No warranty is given or implied in respect of information or
recommendations or that any use of products will not infringe rights belonging to other parties. In any event or occurrence our liability is limited to our invoice value of
the goods delivered by us to you. We reserve the right to change product designs and properties without notice.

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Data sheet
ATEX 94/9/EC for non electrical equipment EN 13463-1:2001
Parameter
Process parameters
Equipment group
Category
Level of protection
Zones Gas vapour mist
Maximum temperature

Minimum temperature
Label details
Equipment Marking
CE marked
Notified body Number
ATEX Number
Indicator details
Display unit
Indicator label
Non Frost block stainless steel side
cladding
Floats
Use of titanium floats
Use of stainless steel floats
Use of plastic floats
Spring damping system

Earth stud
Chamber
Chamber Material

Vessel Flange Material

Bottom chamber Flange Material

Equipment Category 1

Equipment Category 2

Equipment Category 3

II
1
Very High
0
4508C
Note: maximum temperature
also determined by T rating,
materials and any ancillaries
fitted.
-508C

II
2
High
1
4508C
Note: maximum temperature
also determined by T rating,
materials and any ancillaries
fitted.
-508C

II
3
Normal
2
4508C
Note: maximum temperature
also determined by T rating,
materials and any ancillaries
fitted.
-508C

II 1 G c T1.T6
Yes
1180
SIRA 04ATEX 6126

II 2 G c T1T6
Yes
No
SIRA 04ATEX T133

II 3 G c T1.T6
Yes
No
No

Stainless steel clad

Aluminium

Yes
To be earth bonded

Aluminium
Optional: Stainless steel clad
Aluminium
Optional: Stainless steel
Yes
To be earth bonded

Must be fitted with spring

damping
Yes
No
If surging (float velocity)
exceeds 1 m/s.
Note: Maximum process
temperature 2608C
Required if Non-frost block
are fitted

Must be fitted with spring

damping
Yes
No
If surging (float velocity)
exceeds 1 m/s.
Note: Maximum process
temperature 2608C
Required if Non-frost block
are fitted

Yes

Austenitic stainless steel,

super austenitic stainless
steel and nickel based
alloys.

Austenitic stainless steel,

super austenitic stainless
steel and nickel based
alloys.

Carbon
steel,
duplex,
austenitic stainless steel,
super austenitic stainless
steel and nickel based
alloys.
Carbon steel, duplex flanges,
a spring damper must be
fitted.
Austenitic stainless steel,
super austenitic stainless
steel and nickel based
alloys.
Note:
If
float
velocity
exceeds 1 m/s a spring
damper must be fitted

Carbon
steel,
duplex,
austenitic stainless steel,
super austenitic stainless
steel and nickel based
alloys.
Carbon
steel,
duplex,
flanges, a spring damper
must be fitted.
Austenitic stainless steel,
super austenitic stainless
steel and nickel based
alloys.
Note:
If
float
velocity
exceeds 1 m/s a spring
damper must be fitted

Stainless steel

Aluminium
No

Yes
No
If surging (float velocity)
exceeds 1 m/s.
Note: Maximum process
temperature 2608C
As requested

Austenitic stainless steel,

super austenitic stainless
steel and nickel based
alloys.
Titanium Grade 2.
Carbon
steel,
duplex,
austenitic stainless steel,
super austenitic stainless
steel and nickel based
alloys.
Carbon
steel,
duplex,
austenitic stainless steel,
super austenitic stainless
steel and nickel based alloys
flanges.
Note:
If
float
velocity
exceeds 1 m/s a spring
damper must be fitted.

Documentation
Declaration of conformity
Yes
Yes
Yes
IOM
Yes
Yes
Yes
Notes:
1)
For hydrogen service a titanium float must not be used.
2)
For saturated steam service only, the environment within the gauge will be non-hazardous regardless of the zone
outside, a non-cushioned spring assembly can be fitted. (The maximum temperature is determined by T rating,
the material used and any ancillaries fitted).
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