Spirax Sarco LP40 User manual

IM-P693-08 EMM Issue 2 1
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
850152-01
LP40
High Integrity,
Self-monitoring Low Level Alarm Probe
Installation and Maintenance Instructions
IM-P693-08
EMM Issue 2
1. Safety information
2. General product information
3. Installation
4. Wiring
5. Probe clearance test
procedure
6. Maintenance
7. Spare parts
8. Technical assistance
© Copyright 2020
Printed in Germany

IM-P693-08 EMM Issue 2
2
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Your attention is drawn to any National or local regulations.
The product is designed and constructed to withstand the forces encountered during normal use.
Use of the product for any other purpose, or failure to install the product in accordance with these
Installation and Maintenance Instructions, could cause damage to the product and may cause
injury or fatality to personnel.
The LP40 level probe and LCS3050 level switch comply with the requirements of the Pressure
Equipment Directive (PED) and carry the mark. They are classed as Safety Accessories and
therefore fall within Category 4 of the Directive.
Warning
If this product is not used in the manner specified by this IMI, then the protection provided may
be impaired.
1.1 Intended use
The Level probe LP40 is designed for use in conjuction with the Spirax Sarco low water level switch
LCS3050. If used in conjuction with other controllers then a safety power supply unit that delivers
a Safety Extra Low Voltage (SELV) must be used to supply the controller/probe.
i) Check that the product is suitable for use with the intended fluid.
ii) Check material suitability, pressure and temperature and their maximum and minimum values.
If the maximum operating limits of the product are lower than those of the system in which it
is being fitted, or if malfunction of the product could result in a dangerous overpressure or
overtemperature occurrence, ensure a safety device is included in the system to prevent such
over-limit situations.
iii) Determine the correct installation situation and direction of fluid flow.
iv) Spirax Sarco products are not intended to withstand external stresses that may be induced by
any system to which they are fitted. It is the responsibility of the installer to consider these
stresses and take adequate precautions to minimise them.
v) Remove protection covers from all connections and protective film from all name-plates, where
appropriate, before installation on steam or other high temperature applications.
Safe operation of these products can only be guaranteed if they are properly installed, commissioned,
used and maintained by qualified personnel (see Section 1.11) in compliance with the operating
instructions. General installation and safety instructions for pipeline and plant construction, as
well as the proper use of tools and safety equipment must also be complied with.
1.2 Access
Ensure safe access and if necessary a safe working platform (suitably guarded) before attempting
to work on the product. Arrange suitable lifting gear if required.
1.3 Lighting
Ensure adequate lighting, particularly where detailed or intricate work is required.
1. Safety information

IM-P693-08 EMM Issue 2 3
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
1.4 Hazardous liquids or gases in the pipeline
Consider what is in the pipeline or what may have been in the pipeline at some previous time.
Consider: flammable materials, substances hazardous to health, extremes of temperature.
1.5 Hazardous environment around the product
Consider: explosion risk areas, lack of oxygen (e.g. tanks, pits), dangerous gases, extremes of
temperature, hot surfaces, fire hazard (e.g. during welding), excessive noise, moving machinery.
1.6 The system
Consider the effect on the complete system of the work proposed. Will any proposed action (e.g.
closing isolation valves, electrical isolation) put any other part of the system or any personnel at risk?
Dangers might include isolation of vents or protective devices or the rendering ineffective of controls
or alarms. Ensure isolation valves are turned on and off in a gradual way to avoid system shocks.
1.7 Pressure systems
Ensure that any pressure is isolated and safely vented to atmospheric pressure. Consider double
isolation (double block and bleed) and the locking or labelling of closed valves. Do not assume
that the system has depressurised even when the pressure gauge indicates zero.
1.8 Temperature
Allow time for temperature to normalise after isolation to avoid danger of burns.
1.9 Tools and consumables
Before starting work ensure that you have suitable tools and/or consumables available. Use only
genuine Spirax Sarco replacement parts.
1.10 Protective clothing
Consider whether you and/or others in the vicinity require any protective clothing to protect against
the hazards of, for example, chemicals, high/low temperature, radiation, noise, falling objects, and
dangers to eyes and face.
1.11 Permits to work
All work must be carried out or be supervised by a suitably competent person.
Installation and operating personnel should be trained in the correct use of the product according
to the Installation and Maintenance Instructions.
Where a formal 'permit to work' system is in force it must be complied with. Where there is no such
system, it is recommended that a responsible person should know what work is going on and, where
necessary, arrange to have an assistant whose primary responsibility is safety.
Post 'warning notices' if necessary.
1.12 Handling
Manual handling of large and/or heavy products may present a risk of injury. Lifting, pushing,
pulling, carrying or supporting a load by bodily force can cause injury particularly to the back.
You are advised to assess the risks taking into account the task, the individual, the load and the
working environment and use the appropriate handling method depending on the circumstances
of the work being done.
1.13 Residual hazards
In normal use the external surface of the product may be very hot. Many products are not self-
draining. Take due care when dismantling or removing the product from an installation.

IM-P693-08 EMM Issue 2
4
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
1.14 Freezing
Provision must be made to protect products which are not self-draining against frost damage in
environments where they may be exposed to temperatures below freezing point.
1.15 Safety information - Product specific for level control and
level limit switch/alarm products in steam boilers
Products/systems must be selected, installed, operated, and tested in accordance with:
-Local or National standards and regulations.
-Guidance Notes, (Health and Safety Executive BG01 and INDG436 in the UK).
-The requirements of Approvals Authorities.
-Boiler Insurance Bodies.
-Boiler manufacturer’s specifications.
The boiler must be depressurised and vented to atmosphere before installation of the probe.
Two low water level probes must be installed on steam boilers. The controller alarm relays must
disconnect the boiler heat supply at low alarm status. Low level probes must be installed in separate

A combination of low water level probe and a level probe or high water level probe together in one
protection tube/chamber is possible as well (check local regulations).
A high water alarm may be part of the water level control, or a separate system. An independent
high water alarm system must be fitted if it is considered a safety requirement. In this case, the
relays must simultaneously isolate the feedwater supply and the boiler heat supply at high alarm
status. All boiler water limit switches alarms require regular functional testing.
Under certain circumstances the water level in a boiler can be different to that shown in the gauge
glass.
Separate literature is available from Spirax Sarco on this subject.
Do not install the probe outdoors without additional weather protection.
Drain/vent holes must be kept clear - do not cover.
A suitable water treatment regime must be used to ensure continuous safe and correct operation
of the control and alarm systems. Consult the above authorities and a competent water treatment
company.
1.16 Disposal
Unless otherwise stated in the Installation and Maintenance Instructions, this product is recyclable
and no ecological hazard is anticipated with its disposal providing due care is taken.
1.17 Returning products
Customers and stockists are reminded that under EC Health, Safety and Environment Law, when
returning products to Spirax Sarco they must provide information on any hazards and the precautions
to be taken due to contamination residues or mechanical damage which may present a health,
safety or environmental risk. This information must be provided in writing including Health and
Safety data sheets relating to any substances identified as hazardous or potentially hazardous.

IM-P693-08 EMM Issue 2 5
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
2.1 General description
The Spirax Sarco LP40 level probe is used with the
Spirax Sarco LCS3050 level switch to provide a high
integrity, self-monitoring low level alarm signal, usually in a
steam boiler. It consists of a probe body with a removable
cable socket, and a separate screw-on probe tip. The tip is
retained with a roll pin, and held in place with a lock-nut.
Two level probes and a limit switch are normally installed
on each boiler for safety reasons. In many countries a first
and second low alarm is used. The LP40 in conjuction with
the LCS3050 is used to provide the second low alarm.
The first low alarm can be provided using the MIN alarm
output of the level controller. The probe is suitable for boiler
pressures of up to 32 bar g (464 psi g).
2.2 Available tip lengths mm (inches)
500 (19.7), 1 000 (39.4) and 1 500 (59).
2.3 Pressure/temperature limits
Nominal pressure rating PN40
Maximum boiler pressure 32 bar g (464 psi g)
Maximum operating temperature 239 °C (462 °F)
Maximum ambient temperature 70 °C (158 °F)
Designed for a maximum cold
hydraulic test pressure of: 60 bar g (870 psi g)
2.4 Technical data
Maximum probe cable length See Level switch IMI
Degree of protection IP54
2.5 How the LP40 works
The probe has a level sensing tip (probe tip) and a comparator
tip. The earth return path is via the body connection.
Under normal operating conditions, the probe tip is immersed,
and the resistance to earth is low. When the water level drops
below the probe tip the resistance to earth becomes high,
causing the level switch to give a low level alarm signal.
The comparator tip compensates for any leakage to earth
caused by scale, dirt, or internal moisture, ensuring a low
water alarm signal even under adverse conditions.
A DIN 43650 cable socket is supplied with each unit and is
provided with a Pg 11 cable gland.
WARNING: It is essential that the probe tip does not
touch any part of the boiler. Standards require that the
tip is at least 14 mm (") from the protection tube, and
this must be checked when the probe is installed. See
Section 5, 'Probe clearance test procedure'.
Fig. 1 LP40
Cable
socket
Pg 11
cable
gland
Probe body
27 A/F
½" BSP
taper
connection
Probe tip
Comparator
tip
2. General product information

IM-P693-08 EMM Issue 2
6
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Before proceeding with any installation or maintenance read Section 1, 'Safety information'.
When the probe is to be installed in the boiler, ensure it is positioned at least 1 metre (39") from any safety
valve or steam take-off, as increased localised water levels may occur.
3.1 Deciding on the low alarm levels
In most shell boilers the water will 'swell' when it is firing, such that the actual water level will be higher than
the level shown in the gauge glass. In practice this can be up to 50 mm (2") in very large boilers reducing to
about 10 mm (") in smaller ones. We recommend, therefore, that the second low level alarm should be well
above the bottom of the gauge glass when the boiler is cold, as this will reduce when the boiler is firing. The
first low level alarm (provided by a level controller) may be 20 mm (¾") above second low level alarm (see
Figure 3). Wherever possible the boiler manufacturer should be consulted for advice on the working and
alarm water levels.
Boiler cold Boiler firing
Level gauge glass
2nd low
1st low
(Level controller)
Fig. 2
Typical low alarm levels
2nd low
1st low
(Level controller)
3.2 Protection tube
The probe must be installed in a protection tube when used as a low level alarm in a steam boiler. The
protection tube provides a relatively steady water level, shielding the probe from the turbulence in the boiler.
Two separate protection tubes must be provided, one for each LP40 probe. Typical protection tubes and
installation examples are shown in Figures 3, 4 and 5. Dimensions and construction may be varied to suit
the application, but a tube of at least 80 mm (3") diameter is recommended.
Flange lagging is recommended, particularly on larger boilers or boilers with a working pressure over
10 bar g (145 psi g). Do not lag the probe.
Do not cover the vent or drain holes on the body.
Note: When making flanged or screwed joints, ensure that excess jointing compound does not enter the
boiler.
3. Installation

IM-P693-08 EMM Issue 2 7
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Boiler shell
20 mm (¾") vent hole as
high as possible
20 mm (¾")
Fig. 3 Typical protection tube
Minimum Ø 80 mm

IM-P693-08 EMM Issue 2
8
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
*
Fig. 4 Installation example 1: Inside the boiler with protection tube provided by the customer
Thread Rp ½ Mounting flange for probe LP40
Flange DN 50 PN 40

Reducer K88.9x60.3x3.2 EN 10253-2
Protection tube >= DN 80
Probe rod
Reducer K88.9x30x3.2
Vent hole as high as possible
- high water level mark at least 20 mm below middle of vent hole
Lowest possible LW mark (upper bond)
* The lowest water level should be higher than the zero point
of the water level measurement

IM-P693-08 EMM Issue 2 9
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Vent hole as high as possible
- high water level mark at least 20 mm below middle of vent hole
Fig. 5 Installation example 2: Combination with capacitance level probe LP21
Thread Rp ½ Mounting flange DN100 for the combination probe
LP21 + LP40
Flange DN 100 PN 40
Probe rod LP40
Protection tube >= DN 100
Lowest possible LW mark (upper bound)
* The lowest water level should be higher than the zero point
of the water level measurement
Reducer K114.3x28x4
Level probe
LP21
Zero point of
the water level
measurement
Unusable
length
Vent hole as high as possible
- high water level mark at least 20 mm below middle of vent hole

IM-P693-08 EMM Issue 2
10
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
3.3 Cutting the probe tip
The probe is normally installed vertically, but for probe tip lengths of up to 500 mm (20") it may be inclined
by up to 45°from the vertical. The low alarm switching level is at the extreme end of the probe tip, which is
cut to length to give the required alarm level.
LP40 probe tips are retained by a thread, pin and lock-nut:
- Earlier probes were retained by two pins only.
- A compatable tip is available to special order.
For existing installations, it is important to check which type of connection is used before cutting the probe
tip to length.
3.3.1 Procedure for cutting the tip:
- Screw the lock-nut onto the probe fully, but do not tighten it at this stage.
- Use an M6 spanner on the flats of the probe tip connector to prevent it rotating.
WARNING: If the threaded end of the connector is allowed to rotate in the probe body, the
internal wiring will be damaged.
- Screw the probe tip onto the probe until the hole in the probe lines up with the bottom of the slot in the
probe tip (see Figure 7).
- Support the assembly and tap in the retaining pin until an equal length protrudes from each side of the
probe tip.
- Tighten the lock-nut onto the probe tip (5-7 N m, 4-5 lbf ft).
- Ensure the boiler water is at the required low alarm level.
- Mark a line down the length of the probe tip using a water-soluble felt pen.
- Temporarily fit the probe and tip to the boiler (½" BSP taper).
- Remove the probe and note the point at which the ink is dissolved by the water.
- Use a fine hacksaw to cut the probe tip to this length (see Figure 7).
- Deburr tip.
- Carry out the probe clearance test procedure (see Section 5, 'Probe clearance test procedure') and
record the results.
Note: A chart is provided for recording this data.

IM-P693-08 EMM Issue 2 11
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Dipped
length
6 mm flat
Lock-nut
Retaining pin
at bottom of
slot
Probe tip
Fig. 6
Fig. 7
Probe body
15 mm (½")
approximately
3.3.2 Install the probe as follows:
- Ensure both male and female threads are in good
condition.
- Use up to three turns (no more) of PTFE thread
sealing tape on the probe thread.
WARNINGS: Do not use excessive tape. Do not
use paste type jointing compound.
- Fit and tighten the probe by hand initially.
- Use a suitable spanner to tighten the probe. Under
no circumstances use a pipe wrench.
- Due to the nature of a taper/parallel joint it is not
possible to recommend tightening torque figures.
- Do not overtighten - there should always be visible
thread on the probe.
- Note: The probe thread will not 'bottom out' (i.e.
probe body hexagon contacts the face of the female
screwed connection), unless there is excessive wear
or an out-of-tolerance female thread, in which case
it will be necessary to replace or re-work the flange
or connection.
3.3.3 Subsequent removal and refitting:
WARNING: Ensure boiler or vessel is depressurised
and vented to atmosphere before attempting to
unscrew or remove the probe.
- Always use the correct size spanner - not a pipe
wrench.
- Inspect male and female threads for signs of
damage, which may have occurred through
overtightening, leading to torn threads or even
localised cold welding (galling/picking up).
- If damage has occurred replace the probe.

IM-P693-08 EMM Issue 2
12
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Refer to the relevant level limit switch documentation/wiring diagram for full information, including screen
connection details.
Cabling should be installed in accordance with BS 6739 - Instrumentation in Process Control Systems:
Installation design and practice or local equivalent. For US and Canadian installations the probe must be
wired in accordance with the National and Local Electrical code (NEC) or the Canadian Electrical code
(CEC). To connect the level probe please use screened multi-core cable, min. conductor size 0,5 mm²,
e.g. LiYCY 4 x 0,5mm², max. length 100 m.
Ensure that sufficient cable length is provided to allow removal of the cable socket and to ensure that no
strain is placed on the unit.
To unplug the cable socket, remove the central screw.
Note: To provide environmental protection the probe is supplied with a gasket between the cable
socket and the probe connector. To maintain environmental integrity, ensure the gasket is always
present when reconnecting cable socket and that all contact surfaces are clean and undamaged.
To gain access to the connector block within the cable socket, remove the central screw and withdraw the
hinged cover.
The connector block on the LP40 maybe rotated in 90° steps to facilitate wiring:
-Remove the retaining screw and withdraw socket.
-Remove connector block and reposition as required.
1Probe tip
2Comparator tip
3Comparator tip
3
2
1
Fig. 8
View of connector block removed from cable connector Earth
4. Wiring

IM-P693-08 EMM Issue 2 13
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Fig. 9a Comparator tip
Screen
Internal link
Low alarm tip
LP40 connector
Ensure that resistance from the probe body to
boiler shell is less than 1 Ω.
LCS3050 limit switch
Alarm 1 (AL1)
1
2
4
3
Ensure Screen is connected to the
(CEP) central earthing point in the
control cabinet
5
Fig. 9b
Screen
LP40 connector
Ensure that resistance from the probe body to
boiler shell is less than 1 Ω.
LCS3050 limit switch
Alarm 2 (AL2)
9
10
12
11
Ensure Screen is connected to the
(CEP) central earthing point in the
control cabinet
13
Comparator tip
Internal link
Low alarm tip

IM-P693-08 EMM Issue 2
14
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
LP40 LP40
Connection thread
out of line
Water level
Minimum 40 mm (1")
Dimensions less
than 14 mm (")
Potentially hazardous
Minimum 14 mm (")
when installed
Correct
5.1 Introduction
To ensure safe, correct operation of the system, it is essential that the probe tip does not touch any part of
the boiler or protection tube. Standards require that the probe tip has at least 14 mm (") clearance.
This test confirms that the LP40 probe is installed correctly. The test must be done on initial installation, and
each time the probe is removed from the boiler, e.g. for annual inspection.
A pair of 'checking wires' are used in conjunction with an Insulation Resistance Tester (meter) to test if there
is less than 14 mm (") radial clearance from the tip end. This is indicated by a 'short circuit' (i.e. a reading
less than infinity).
When correctly carried out, the test will ensure that the final probe tip position is at least 14 mm (") from
the protection tube. See Figure 10.
Fig. 10
5. Probe clearance test procedure

IM-P693-08 EMM Issue 2 15
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Pinch together (to relax coil) for fitting to probe tip
Maximum 10 mm (")
90°
14 mm (") End view
Side view
Fig. 11
Fig. 12
5.2 Test method
1. Drain water level to at least 50 mm (2") below alarm level and vent boiler or vessel to atmosphere.
2. Remove probe (if installed) and fit a pair of checking wires to the end of the probe tip, 90°relative to
each other and a maximum 10 mm (") from the tip end - see Figures 11 and 12.
3. Carefully pass probe through screwed connection and into the protection tube. The checking wires will
deflect to allow them to pass through, and then spring back to their original positions.
4. Screw down probe by hand, without using PTFE tape.
5. Attach the earth lead of the meter to the boiler and the live lead to pin 1 of the probe connector. Check
the contact to boiler with the meter.
6. Activate meter and observe display. Slowly unscrew probe one full turn (without unduly rocking the probe).
7. If no short circuit is found, disconnect the meter leads, unscrew and withdraw the probe, taking care not
to catch the checking wires on the underside of the screwed connection.
8. Remove checking wires and install probe as described in Section 3, 'Installation'.
9. Low alarms must be functionally tested by lowering the water level before the boiler is allowed to run
unsupervised. Separate literature describes this procedure.
10. Complete the clearance record sheet (see page 16 and 17).
Warning: It is essential to remove the checking wires from the probe before commissioning the
boiler or vessel. Failure to do this could lead to the low alarms not working.
If a short circuit was found during the test then further investigation is needed. Some possible reasons are
listed below:
-Probe tip bent or not attached properly.
-Protection tube and/or screwed connection out of alignment.
-Protection tube not of large enough bore and/or not deep enough (the tube should be at least 40 mm
(1") deeper internally than the end of the probe, see Figure 10).

IM-P693-08 EMM Issue 2
16
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
5.3 Probe clearance record sheet
We strongly recommend that a record of the probe clearance test is kept, and a sheet is provided for this
purpose. This must be completed each time the probe is fitted/refitted.
How to complete the sheet:
-Date: The date the test procedure was carried out.
-Reason for test: Initial installation or annual inspection.
-Clearance 14 mm ("): A signature in this box signifies the test has been successfully completed,
verifying the tip clearance is greater than 14 mm (").
-The (competent) person who did the tests must sign this box.
Date Reason for test
Verification Signatures
Clearance
14 mm (") or more Checking wires removed Independent assessor

IM-P693-08 EMM Issue 2 17
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Date Reason for test
Verification Signatures
Clearance
14 mm (") or more Checking wires removed Independent assessor
-WARNING: It is essential to remove the checking wires from the probe before commissioning
the boiler or vessel. Failure to do this could stop the low water alarms operating.
-The person who removes the checking wires must sign the record sheet to verify that this has been
completed.
-Independent assessor: It is strongly recommended that an independent person (who might be an
Insurance Inspector, for example) verifies:
-That the test has been carried out.
-That the checking wires have been removed.
-That the record sheet has been correctly completed by a competent person.

IM-P693-08 EMM Issue 2
18
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Probe body cleaning instructions - Use a cloth dampened with tap/de-ionised water or isopropyl alcohol.
Use of other cleaning materials could damage the product and invalidate the warranty.
Boiler water level controls + level alarms - Require regular testing and inspection. For specific testing
instructions for Spirax Sarco systems please see separate literature.
The spare parts available are detailed below. No other parts are supplied as spares.
Available spares
LP40 tip retaining pins Stock No. 4024780 Pack of 10
Spring clearance checking set Stock No. 4024781 1 set (2 springs)
How to order spares
Always order spares by using the description given in the column headed 'Available spares' and state for
which product they are required.
Example: 1 off Spring clearance checking set for a Spirax Sarco LP40 high integrity, self-monitoring low
level alarm probe.
6. Maintenance
7. Spare parts

IM-P693-08 EMM Issue 2 19
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
8. Technical assistance
Contact your local Spirax Sarco representative. Details can be found on accompanying order /delivery
documentation or on our web site:
www.spiraxsarco.com
Returning faulty equipment
Return all items to your local Spirax Sarco representative. Ensure all items are suitably packed for transit
(preferably in the original cartons).
Please provide the following information with any equipment being returned:
1. Your name, company name, address and telephone number, order number and invoice and return
delivery address.
2. Description and serial number of equipment being returned.
3. Full description of the fault or repair required.
4. If the equipment is being returned under warranty, please indicate:
a. Date of purchase.
b. Original order number.

IM-P693-08 EMM Issue 2
20
LP40 High Integrity, Self-monitoring Low Level Alarm Probe
Spirax Sarco Ltd
Runnings Road
Cheltenham
GL51 9NQ
United Kingdom
www.spiraxsarco.com