1 Safety information
Comply with national or local regulations.
The product is designed and constructed to withstand the stresses encountered during use. Using the product for any purpose other than its intended use, or installing it incorrectly without following the installation and maintenance instructions, may damage the product and cause injury or death.
This pressure equipment does not bear the CE mark and is classified as “Sound Engineering Practice” (SEP) under Article 3, Paragraph 3 of the Pressure Equipment Directive.
Note: Under the regulations, SEP products do not bear the CE mark.
Warning:
If the product is not used as specified in this Installation and Maintenance Instructions (IMI) document, the protection provided may be impaired.
1.1 Preparation before use
- Check that the product is suitable for the intended fluid.
- Check that the materials are suitable and verify the maximum and minimum pressure and temperature values. If the product’s maximum allowable temperature is lower than that of the system in which it will be installed, or if a product malfunction could result in overpressure or overtemperature, ensure that the system includes safety devices to prevent conditions exceeding the allowable limits.
- Determine the correct installation position and fluid flow direction.
- Spirax Sarco products are not designed to withstand external stresses imposed by the system. The installer is responsible for taking these stresses into account and implementing adequate measures to minimize them.
- When the product is used with steam or other high-temperature fluids, remove all connection protection caps and the protective film from the nameplate before installation.
Correct installation, commissioning, use and maintenance by qualified personnel in accordance with the operating instructions are the only guarantees of safe operation of this product (see Section 1.11). During installation, comply with the installation and safety instructions for the piping and plant structure, use suitable tools and provide the necessary safety equipment.
1.2 Access
Ensure safe access. Before operating the product, provide a safe working platform. If necessary, arrange suitable lifting equipment.
1.3 Lighting
Ensure adequate lighting, particularly when carrying out complex work.
1.4 Hazardous liquids or gases in the piping
Consider the medium in the piping and its condition, including flammable substances, substances hazardous to health and substances at extreme temperatures.
1.5 Hazardous environments around the product
Consider environments where there is a risk of explosion, a lack of oxygen, such as in tanks or pits, extreme temperatures, hot surfaces, a risk of ignition, such as during welding, excessive noise or moving machinery.
1.6 The system
Consider the effect of the work on the complete system. Could any operation, such as closing an isolation valve or electrical isolation, place another part of the system or personnel at risk?
Hazards may include isolating exhaust or protective devices, or disabling controls or alarms. Ensure that isolation valves are opened and closed slowly to avoid system shocks.
1.7 Pressure systems
Ensure that all pressure is isolated and safely vented to atmosphere. Consider double isolation, such as two shut-off valves and venting, and lock or tag closed valves. Do not assume that the system is depressurized even when the pressure gauge indicates zero.
1.8 Temperature
After isolating the valve, allow it to cool to ambient temperature to avoid burns.
1.9 Tools and consumable items
Before starting work, ensure that suitable tools and available consumable items are provided. Use only Spirax Sarco replacement parts.
1.10 Protective clothing
Consider whether protective clothing is required to protect against hazards such as chemicals, high or low temperatures, noise, falling objects and risks to the eyes and face.
1.11 Work permits and qualifications
All work must be carried out or supervised by qualified personnel. Installation and maintenance personnel must be trained and understand the correct use of these products in accordance with the instructions.
A formal work permit system must be followed. If no such system is available, the responsible person should understand how the work is to be carried out and, where necessary, appoint a person responsible for safety. Warning notices should be displayed where required.
1.12 Handling
Manual handling of Spirax Sarco products may cause injury. Lifting, pushing, pulling, carrying or supporting loads with the body may cause injury, particularly to the back. It is recommended that the risks be assessed, taking into account the work, personnel, load and working environment, and that correct handling methods be used.
1.13 Other hazards
During normal use, the external surface of the product may become very hot.
Many products are not self-draining. Exercise caution when dismantling or removing the product from the installation piping (refer to the Maintenance Instructions).
1.14 Freezing
For products without self-draining capability, protection must be provided when they are used in conditions where the ambient temperature is below freezing, to prevent freezing damage.
1.15 Safety information - special instructions for products used for steam boiler water level control and level limiting or alarm functions
The product must be selected, installed, operated and tested in accordance with the following:
- Local or national standards and regulations
- Guidance manuals
- Requirements of the approved inspection authority
- Boiler insurance requirements
- Boiler manufacturer’s instructions
Steam boilers must be fitted with two independent water level limit or alarm systems. The level sensors must be installed in separate protection tubes or chambers, with sufficient clearance at the sensor tips and at the bottom.
Each sensor must be connected to an independent controller. In the event of a low-level alarm, the alarm relay must shut off the boiler firing system.
The high-water alarm must form part of the water level control system or be a separate system. Where required by safety considerations, a separate high-water alarm system must be installed. In this case, when a high-water alarm occurs, the relay must simultaneously shut off the boiler feedwater and firing systems. All boiler water level limiting and alarm systems require regular functional testing.
Suitable water treatment practices must be used to ensure continuous, safe and correct operation of the water level control and limiting systems. Consult a qualified water treatment company.
1.16 Disposal
This product is recyclable. Proper disposal does not create an environmental hazard.
1.17 Returning products
When users and retailers return products to Spirax Sarco, they must comply with UK and EC health, safety and environmental regulations. Information on any residues that are contaminated or may present a health, safety or environmental hazard, together with the precautions to be taken, must be provided. This information must include data sheets for any substances identified as being relevant to health and safety.
2 Product information
2.1 General description
The Spirax Sarco LP10-4 level sensor is used with the Spirax Sarco LC1300 controller to provide level control and alarm functions for boilers, tanks or other vessels. It is suitable for a wide range of conductive liquids.
2.2 Pressure and temperature limits
| Item | Metric | Imperial |
|---|---|---|
| Standard pressure rating | PN40 | - |
| Maximum pressure | 32 bar | 464 psi g |
| Maximum temperature | 239 °C | 462 °F |
| Maximum ambient temperature | 70 °C | 158 °F |
| Minimum ambient temperature | -20 °C | -4 °F |
2.3 Technical data
| Item | Value |
|---|---|
| Enclosure rating | IP54 |
| Pollution degree | 3 |
| Maximum cable length, sensor to controller | 30 m (98 ft) |
| Maximum sensing depth | 2095 mm (82.5”) |
| Minimum sensing depth | 75 mm (3”) |
| Minimum conductivity when used with an LC1300 level controller | 1 μS/cm @ 25 °C (77 °F) |
2.4 Operating principle of the LP10-4 level sensor
The LP10-4 has four removable probes that can be cut to the required lengths according to the levels to be controlled. The sensor body is grounded through the 1” threaded connection, forming a ground circuit with the boiler or vessel. If the sensor is used in a non-conductive tank, such as a concrete or plastic tank, one of the probes is used as the ground connection, or a separate ground connection must be provided.
When a probe is immersed in a conductive liquid, a current circuit to ground is completed. When the liquid level falls below the probe, the resistance to ground increases and a signal is sent to the controller indicating that the liquid level has fallen below the probe.
Figure 1
Figure 2
3 Installation
3.1 Introduction
When used on steam boilers, the probe assembly may be installed either outside or inside the steam drum. Installation inside the steam drum requires a protection tube. Suitable designs are covered in separate documentation.
Warning
Although two probe assemblies may be installed in one protection tube, where two low-water alarms are required on a boiler they must be completely independent. Separate probe assemblies, separate protection tubes or chambers, and separate controllers must be used.
Where necessary, consult the boiler manufacturer for advice on water level operation and alarms.
Warning
In certain circumstances, the water level in the boiler may differ from that indicated by the gauge glass. Refer to dedicated Spirax Sarco literature for this condition.
Do not install the probe assembly outdoors without a protective enclosure.
The probe assembly is designed for installation in a 1” BSP (Rp1) or 1” NPT threaded connection. Specify the thread type for new installations.
Probe spacers provide lateral support and electrical insulation between probes.
The level switches are located at the lower ends of the sensor probes. The probes may be cut to the required length and transmit a signal to the controller when an alarm condition occurs. The supplied probe assembly has four probes, each 1000 mm (3.28 ft) long, with extension couplings, locking nuts, and two spacers. If required, two probes may be joined to provide a maximum length of 2095 mm (6.87 ft).
Warning
Probe spacers are essential components and must be installed. Failure to install probe spacers may cause short circuits between probes or contact between probes and the protection tube. This is potentially hazardous.
3.2 Installation Procedure
Warning: To prevent bending or twisting of the sensor probes, support them along their length when handling the probe assembly, especially where the length exceeds 1 m / 39”. Do not allow the probes to rotate in the probe assembly body when tightening couplings or locking nuts.
- Fit the four probes to the probe assembly using the supplied extension couplings and locking nuts.
- Ensure that each extension coupling is securely screwed onto the sensor probe.
- Tighten the locking nuts.
- Connect the sensor probes, ensuring that they are the required length and that all probes are fitted with probe spacers.
- Fit a probe spacer at the end of the probes.
- Remove the plastic cap supplied in the packaging, or use another suitable protective cap, and press it onto the sensor probes using the palm of your hand. Once the plastic cap is fitted, the probe spacer can be easily positioned along the probes.
- Fit the second probe spacer in the same way. See Figure 3.
- If required, fit a second set of extension couplings, sensor probes, and two additional spacers in the same way.
- Tighten the coupling locking nuts.
Warning
Failure to tighten the locking nuts may cause the probes to loosen or fall out.
- Set the liquid level at the first required level, for example, the low-water alarm level. Typically, the levels measured by a four-probe assembly may be high water, alarm, pump off, pump on, and low-water alarm.
- Mark a metal rod using a water-soluble felt-tip pen, insert it into the boiler, and measure the depth from the top of the probe assembly connection to the liquid level. Alternatively, read the liquid level from the gauge glass.
- Mark the liquid level on the sensor probe, measuring from the underside of the probe assembly body. Mark the intended cutting position on the sensor probe using a file or hacksaw. The insertion length must be greater than 15 mm (0.6”). Recheck before cutting the probe to the required length. See Figure 3.
Repeat this procedure for the remaining probes.
Sensor probes are identified by coloured sleeves:
| Brown | Probe 1 | Orange | Probe 3 |
|---|---|---|---|
| Red | Probe 2 | Yellow | Probe 4 |
Position the lowest probe spacer as far above the water surface as possible. This spacer supports all sensor probes and must be at least 15 mm (0.6”) from the end of the shortest probe. The maximum unsupported probe length is 250 mm (9.8”). The shortest probe length is 75 mm (3”) without an extension coupling. See Figure 3.
If fewer than all four sensor probes are fitted to a probe spacer, cut away the unused sections of the spacer. This prevents the spacer from striking the probe assembly mounting connection when the probe assembly is removed for maintenance. See Figure 4.
3.3 Install the Probe Assembly as Follows
Ensure that all male and female threads are in good condition: 1” BSP taper / 1” NPT, 41 A/F.
Wrap three turns, no more, of PTFE thread sealing tape around the probe assembly thread.
Warning: Do not use excessive tape or adhesive compounds such as jointing paste.
Install and tighten the probe assembly by hand first, then tighten using a suitable spanner. Never use a pipe wrench.
Do not overtighten. The thread must remain visible on the probe assembly.
Note: Do not allow the probe assembly thread to bottom out, meaning that the hexagonal face of the probe assembly housing contacts the face of the female threaded connection, unless the female thread is excessively worn or fatigued. In this case, replace or rework the connection.
3.4 Subsequent Removal and Reinstallation
Warning: Before loosening or removing the probe assembly, ensure that the boiler or vessel has been depressurised and drained.
Use a correctly sized spanner. Do not use a pipe wrench.
Check male and female threads for signs of damage. This may result from overtightening, which can damage the threads or cause a cold-welding effect, such as galling or seizure. Replace the probe assembly if damaged.
Figure 3: Standard installation for probe assemblies up to 1000 mm / 39”. For probe assemblies up to 2095 mm (6.87 ft), see Figure 4.
Figure 4: Installation length from 1000 mm to 2000 mm (39” to 6.56 ft), using a second sensor probe section, extension coupling, and spacers.
4 Wiring
4.1 General
Wiring installation shall comply with BS 6739, the design and installation of process control instrumentation systems, or an equivalent local standard.
4.2 Cable Specification
Use 5-core, or 4-core plus 1 earth conductor, 1 mm² (18-16 AWG) high-temperature screened cable. For the LC1300, the maximum cable length is 100 m. Pire FP200 or Delta Crompton Firetuf OHLS cable is suitable for the standard probe assembly.
4.3 Connections
Remove the top cover screws to access the terminal board. The LP10-4 provides four terminals for connection to the sensor probes and one conductive ring terminal for connection to the probe assembly body earth. It can be fitted to an M3 internal thread. See Figure 5.
Bolts and terminal posts are supplied, together with coloured sleeves for identifying the connecting wires. Connection components are available from Spirax Sarco as spare parts, stock number: 402480.
Caution: Do not use standard terminal posts. The supplied terminal posts are high-temperature type.
Use a dual-purpose tool for insulated and conductive terminal posts, such as RS Components or Farnell 210-511, to make the connections.
An M20 cable gland for cable diameters of 5 mm-12 mm is supplied. Removing the cable gland rear nut allows the probe assembly to be connected to Pg16, 1/2” BSP, 1/2” NPT, or M20 flexible conduit fittings. The M20 rear nut is supplied with the product.
Do not install low-voltage cables adjacent to high-voltage cables or switchgear. This may reduce product performance or damage the product. The sensor cable must not share the same conduit or terminal enclosure with power cables or other cables.
Ensure that internal wiring and ring terminals are not trapped or damaged during installation. Before commissioning the system, remove the top cover and inspect the wiring.
Remove the gland support pad to facilitate access to the cable glands:
- Remove the top cover and gland support pad, then complete the wiring in the lower cover. Ensure that sufficient cable or flexible conduit length is available so that the wiring is not under tension.
- Do not overtighten the top cover bolts.
Figure 5
4.4 Screen Connection
An earth loop is created if earthing is provided through two points at different potentials. When correctly installed, the sensor cable screen is earthed at one end only.
Caution: The probe assembly earth is a functional earth, not a protective earth.
Protective earth provides protection against electromagnetic disturbances under individual fault conditions.
Functional earth is used for product operation. In this case, the earth terminal, the boiler shell, serves as the common earth for the probe assembly and also provides a discharge path for other electromagnetic interference.
- Ensure that the screen is connected to the common earth terminals of the probe assembly and controller.
- Ensure that the controller common earth terminal has no internal earth connection. All Spirax Sarco boiler control products are internally isolated from earth.
- The controller common earth terminal must be earthed only through the probe assembly.
Caution: Do not connect the controller common earth terminal to a local earth.
This will create an earth loop and may reduce product performance or damage the product.
4.5 Wiring Diagram
LP10-4 wiring terminals
Figure 6
5 Maintenance
This product does not require specific maintenance. Steam boiler water level control systems should be tested regularly in accordance with national and local regulations. In the United Kingdom, the Health and Safety Executive publishes guidance documents.
The UK Health and Safety Executive recommends quarterly testing of boiler control systems. We recommend that this interval is also observed elsewhere unless national or local regulations specify otherwise.
Where boiler operation is satisfactory, water treatment is effective, and routine testing is carried out, the probe assembly requires inspection only once per year.
Users should contact the boiler inspection authority for their individual boiler house to establish a practical testing procedure.
We recommend the following test procedure:
- Depressurise and drain the boiler or vessel, taking account of safety devices.
- Disconnect the controller power supply.
- Remove the probe assembly top cover and check for contamination and moisture.
- Disconnect the wiring and remove the probe assembly.
- Clean the outer cover if required.
- Inspect the probe assembly.
- If required, clean the sensor probes and insulation using a cloth or soft brush. Do not use abrasive or conductive materials, such as steel wool.
Warning
- If scale is present on the probe assembly, it will also be present in the boiler. Consult a qualified water treatment specialist as soon as possible.
- Check that all extension coupling locking nuts are tightened.
- Check the probe assembly control wiring and power wiring.
- Check the probe assembly for damage.
- Reinstall the probe assembly and carry out a complete functional test of the equipment.
Available Spare Parts
| Spare Part | Stock Number |
|---|---|
| Connector | 4024480 |
